Question: shouldn't the comparison be made based on the rolling diameter of the tire rather tha wheel diameter? If the smaller wheel/larger tire diameter combination results in a larger exposed tire area, the some of the gains will be reduced or negated.
**CLARIFICATION!** Why do bigger wheels mean worse efficiency, when the overall tire diameter remains the same? This comes down to aerodynamics. A 20" wheel will cause more of a disruption in airflow than an 18" wheel. That's why Tesla (and others) uses aero covers on their wheels (Car & Driver testing showed it gives about a 3% efficiency bonus at speed). The smaller the wheel, the more of the side profile of the wheel & tire is perfectly flat (the tire is flat, the wheel is open: more tire = more flat area, less open area). Ideally, you'd have just a plain, solid sheet for the wheel, but obviously that's not idea for brake cooling. Wheel covers are today's common compromise as they have some airflow, but minimal. Let's bring back big sidewalls! Watch till the end to learn how fat sidewalls will save the planet. Car community doing their part. 💪😂
I just thought of this. When range testing different size wheels in real life, do people account for the speedometer being slightly off due to the size of the entire tire and wheel?
@@mai_kul If I was range testing a vehicle I would NOT use the speedometer. The range tests are either done with a rolling road or other means of monitoring speed and distance.
@@andrewsaint6581 he didn’t run that for wheel size. He ran it because it increased the overall contract patch of his wheels, which gave him more grip.
@@andrewsaint6581 the 6 wheel car had 4 front small wheels to have better grip and better aero on the upper part being flat but has nothing to do with side walls
@Tamara Maschan true, f1 cars try to use small wheels to some extent. I had a similar experience i raced my stock 325 vs a stock 325 but with big wheels and in the 1/4 it did a small difference
It's interesting to me that standard wheel sizes have been increasing over the years from all car manufacturers. It seems like it was just for looks, not for ride quality or efficiency.
On electric and heavy vehicles some of has to do with brake disc size, bigger rims means more room for bigger discs. Another part of it has to do with handling on the limit in heavy vehicles, like when performing evasive maneuvers like the dreaded "moose test" etc. But you are partly right, on some cars it really is just for looks. And many customers would do well NOT to tick those bigger wheel options when ordering a car, I certainly don't.
The size of the vehicles increases too. Also mostly for looks. People drive around in Tundras which are legitimately scarily large with nothing except a handbag with them. They think it looks cool.
What should decide wheel size? Brakes! The brakes need to be large enough for the performance of the vehicle and that alone should decide the wheel diameter.
Big wheels are pretty much worse all around imo. Without watching the video first, tire are usually more expensive, have worse ride quality, more prone to curb rash and bending a rim on a pot hole. Basically worse in the real world.
yeah, i've been looking at swapping the brakes on my car so i can fit 15s. it's nice to not worry about potholes and curb rash, plus better rotation in corners with the skinnier tires. efficiency is cool too, i guess.
Tire and wheel size has increased substantially in the last 30 years. People may not remember this, but cars like the 1990 Honda Accord LX and the 1989 Camry (base version) had 14 inch wheels and used 185/70R 14 tires. As indicated by the 70 aspect ratio, those cars had wide sidewalls and the ride they provided was fine. When I bought a new car in Sept. of 2017, I bought a 2017 Camry LE rather than the 2018 model (which was already being sold) in part to avoid the new dual clutch automatic transmission, but also to get the smallest possible wheel size (16 inches) and the largest aspect ratio (65) I could. Even the higher priced 2017 Camry models forced you to get larger wheel sizes. An article in a car magazine I read several years ago included an interview with an auto executive who was asked why manufacturers kept on using bigger wheels despite the various engineering drawbacks, and he replied that it was largely done for styling reasons.
the main driver, I think, of those "styling reasons" is EU pedestrian impact standards that effectively require a very high hood-line, which in turn causes that "blocky" look with tall fenders, which look silly without big wheels. They're trying to make the wheels proportionate to the chunky look of everything else that the pedestrian impact standards force.
I know this is two years old now but hopefully by now you’ve realized the Camry has a traditional slush box 8 speed auto, not a dual clutch as you stated. Sorry it just triggered my inner autist and I had to comment.
Smaller side shoulder of a tire improves sharp steering in contrast to suspension "ride quality". Today middle driver prefers driveability to comfort. Just a business.
This is true. But also follows that wheel and tyre size *decreased* substantially from 1910 to 1960. Wheels went from 36" on a 1910 car, down to 27" or so on a 1915, down to 21" or so on a 1925 and then down to 18" to 17" to 16" or so in the 1940's and then an even smaller 14" to 15" became the fashion in the late 50's and early 60's, to allow for a lower, sleeker profile of the overall vehicle. These 13" and 14" carried through to 1980's economy cars as you say, but then wheels started to grow bigger again as increasingly low profile radials were developed (starting with radials less than S or standard 82% profile, first coming out in the late 60's). The exotic 16" "low profile" 205/55 R16 that was once the preserve of a Porsche 911 front tyre in 1985 is now the standard tyre on the most base model Toyota Corolla, and the 225/40 R18 that was so exotic when it was a Ferrari 355 front tyre in 1998 is now the standard tyre on a higher trim level Corolla! As cars (unfortunately) get taller again more like 1930's cars -- reverting the change to low, sleek, more aerodynamic designs of the 1970's and 1980's -- it makes sense that wheels would get larger again, even if only for stylistic reasons.
I never realized the impact of intentionally going with 16” cheap tire option rather than the 18”. I’m able to get 40.5 mpg average on a 2.0L focus manual. Watching this video really makes me think that tire choice has a much larger impact on mpg than previously thought.
Great video. When moving between the wheel sizes, the bigger wheels may be heavier. If so would that make a difference? Wondering if a 235 tire in 18 stock wheel is more efficient than 235 tire on a lighter (perhaps forged) 20" wheel.
Wheel weight also has a lot to do with it (which EE has already made a video about). I had aftermarket 20" wheels (at 35 lbs / wheel) installed on my stealth Model 3 Performance, and my energy usage increased to ~270 wh/m. They looked awesome, but I've been doing a lot of road trips lately and wanted better range. I recently purchased a set of the 19" Tesla sport wheels (at 25 lbs / wheel), and my energy usage is now back to ~240 wh/m - much better :-)
@@navid8276 It's a Model 3 that has the big performance motors, but the regular brakes, no spoiler, and no track mode. It's basically a Long Range with bigger motors, so stealthily as fast as a Performance model, but none of the change in looks.
The weight of the wheel will have _zero_ impact on steady-state range. The only time you'd notice it is when accelerating that mass up to a certain speed, ergo, "road trips" would be the _last_ place you'd ever notice a mass difference.
Hope you read that. I made allot of calculations for my 3.0 Continental in order to understand how tire pressure is determined. - wanted to use non standard 235/50/19 winter tires and keep rolling resistance, contact patch, etc. to spec. Turned out the required pressure is 2.4 bar - the same as the stock pressure of the stock size 235/50/18 - see why below. 245/40/20 - 2.7 bar cold pressure - ~3.7% sidewall deformation 255/45/19 - 2.3 bar cold pressure ~ 3.8% sidewall deformation Calculation: 1/2 of axle load is divided by pressure, this gives area of contact patch; Area/width of tire gives length; 1/2 length of contact patch is used to solve right angle triangle as one side, second side - hypothenuse is the non deformed radius and the third side is the effective radius of the loaded tire. Substract r-eff from r-nominal you get amount of deformation in mm. Find percentage from sidewall height and that's your percentage of deformation. If you play enough, you'll find out that taller tires allow for less deformation especially if they are tall and wide. For instance, a 2005 Mustang GT on it's stock 235/55/17 would deform them less than 2% at 2.2-2.4 bar cold. Allot of info can be drawn from this simple calculation. And btw, your added air drag calculation is not correct. A wheel has Cd of 1, so your 0.03m2 should be included roughly 4.5 times in the drag of a 0.22 Cd automobile thus contributing to allot more drag than you came with. Best regards! P.S. you seem to never react to my comments.
@@joby602 how can contact area be the same regardless of width? The wider the tire, the more contact area, no? I get that aspect ratio beyond a certain point isn't going to take away from performance. What is the best for each of these cars for performance, safety, and economy? It depends.
@@joby602 that is very much not true. Contact patch is roughly circular, small changes in the radius of the contact patch result in large changes in area. From my own anecdotal experiences, I replaced 205/75/15 tires with 255/60/15 tires on a RWD car. With the 205s I was very easily able to break the back tires loose and do a burnout on dry, clean pavement. With the 255/60/15 tires it was not easy to break the back tires loose, I simply had grip. Admittedly these were not the same brand of tires, but they were targeted towards the same mid-priced market.
Oh yeah!!! I love this video, Never got to liking Low-profile wheels. Yes they react faster but then again, more expensive, louder, stiffer and doesn't protect rim.
There is more to it than that, a wider tire on the front will give you worse turn in. There is a fine balance and a few other things he doesn't cover in this video that are a major part of efficiency and performance.
Sums it up perfectly. “Bring back big sidewalls and get rid of silly low profile tyres!” Win, win, win win! I do not understand the absolute obsession that many people have with ultra low profile tyres.
they just need to reverse the options pricing. "Oh you want the 18 inch wheels? That will be an extra 1000$" "But it comes stock with 20s" "I know. But the 18s will increase your range by 15%". Of course that argument has no chance against "I'll take the most expensive option please. Spare me the details"
@Peter Evans You are talking about larger diameter tires and what you say is true, but I think the video was about the same overall tire diameter but smaller rims.
So... why does this happen? Why are smaller wheels more efficient? That's what I actually expected you to talk about. The rest of the physics is quite intuitive
Agree. You used Tesla's provided coast down curves, but would love an explanation and the math behind why the curves are different. Is the tire diameter actually slightly different and that is the reason? Or is the weight of the tire/wheel combo different and that accounts for the difference?
More of the mass of the wheel + tire is near the outer edge of the wheel. This requires more torque to turn the wheel with more mass further from the center of the wheel. Less efficient
Recently switched from 18 to 19" wheels on my Model 3 and I thought I was going crazy or my battery was just degrading after my range went almost exactly from 299 to 284 and I noticed higher wh/mi when driving so this video provides great clarity and closure haha.
It would be wonderful if someone did an analysis on various OEM and aftermarket wheels and tires to show how they rank for range efficiency. That way, people could compare them and make informed decisions. Using that along with average tread miles on the tire would be wonderful. This is the kind of stuff I wish Consumer Reports would focus their money on.
I read a guy put 15 inch show tires on his Bolt and gained about 20 miles of range. The snow tires were not even low rolling resistance, where the original tires were. I think they come with 17's.
In Swizterland, we have a lot of those BMW i3 cars. I meet some everytime I go out. I'm always impressed how narrow their tires are when you compair it to 90% of the rest of the market. This is at least one thing that BMW made right on this car.
@@superchargedpetrolhead I don't believe it no. The wideness of the tire is the thing the wind sees when it hits frontal under the car. It can be channeled to some extent. But there is always some air that will frontal attack the wheel base. You can look at eco-protoype racing. The tires are nearly roadbike like.
Last week I swaped the summer for the winter wheels. 19×10 285 45 R19 summer to 235 65 R17 winter. The consumption dropped down about a liter on 100km. Range went from 950km to 1150km. For people who like units in a stone×leg per evening style, that's a difference of 4 miles per gallon and about 120 miles more range! On a X5 Diesel.
My 1987 Subaru GL Wagon had 13 inch wheels. I've never seen those before or since. I wrecked it in 93, put it between two trees and straightened it out with a come-along. Straightened the radiator mounts and a fender with a hammer, slapped in the new radiator and a headlight assembly and drove it another 5 years.
I would like to know what effects driver weight might have on range. To keep math simple while using weights within the reasonably expected range at your local Walmart, you could use a 160lb individual versus a 320 lb individual.
@@Blox117, that's like saying most people who shop at Best Buy aren't going to have three nipples. Most people aren't going to be driving a tesla, regardless of where they shop.
Your theoretical presentation is very impressive. Last year I went from a 19 to 20" wheel on my Model 3 Performance. My daily commute is approximately 100 miles round trip. For the time being I get to enjoy carpool lane access in my state driving solo, so I'm able to cruise at about 75 mph. I've noticed only a 3% real world increase in battery usage.
I used to deliver tires and wheels for a wholesaler/distribution company, and there’s another reason for loss of efficiency with larger wheels. In general, they weigh a hell of a lot more and thus have a lot higher rotating mass which is terrible for overcoming inertia, both for accelerating and for braking. You have to pay a lot for a lighter weight, larger diameter wheel, and if you paid the same “lot more” for a smaller diameter wheel, you’d still get better efficiency and performance.
Tesla's range graph is based on their OEM 18"-21" wheels which also have increasing weights as diameter increases. So the drop in range can be due to increased unsprung weight and not necessarily increases diameter. So if that is the case one can install larger aftermarket wheels (forged or flow formed) that are lighter than the smaller OEM wheel, and possibly achieve the same if not better range.
Wheel weight is irrelevant in steady-state driving, it would have zero impact on range (OK, maybe a minuscule amount due to the curb weight being a tiny fraction higher...) As Jason said in the comments, it's 100% aerodynamics (poorer) of larger wheels of a similar design.
110 mm is about as low as it gets on any car with stock suspension that's on the road, and that would be a first gen bmw z4, but a Honda fit at 130mm is still far lower than a porsche 911.
I've got a '84 V Jetta Gli coupe with the 14" Snowflake wheels on 175/R14 60 tires, and the ride is rough as it is. I don't want to imagine how rough it would be with 16" or 17" rims with low profiles! Low profiles are the high-heels of the automotive world: looks great, but impractical.
This video couldn't have come at a better time. I was in the process of buying new wheels for my M3P. Great to see some factual information to support my decisions, thanks for the informative video!
Bigger (& wider) wheels will very likely increase the stress on the suspension components and the wheel bearings. I kept the same size on my car but searched for lighter wheels to reduce the unsprung weight. Excellent video!!!!
Typically, the wheels are not wider and the tire width is the same. As long as the offset is is the same, even a wider wheel would have no impact on suspension "stress". It's strictly a "+1" or "+2" aspect ratio change for looks alone, nothing else.
Given the popularity of SUVs/Crossovers, especially those with larger wheel base intended for off-roading, I'd be curious to see your analysis of off-road tire efficiency.
The dissertation on the separate effects that go into the resistance is correct, but there is no real mention of WHY a taller sidewall should be more efficient. As a matter of fact, ceteris paribus, a taller sidewall is LESS efficient. More rubber that goes through an hysteris cycle. Proof of this is that taller sidewalls are more comfortable: that's because they deform more under load and we all know DEFORMATION OF HYSTERETIC MATERIAL = ENERGY DISSIPATION. Also: a lower aspect ratio tyre weighs LESS than a higher aspect ratio, if the width is kept constant. The additional weight of the rim does not offset this difference, usually. The overall diameter stays constant, as you showed, so there is no big difference in rotational inertia, too. What you mixed here are different things: - lower sidewalls imply larger rims/spokes ---> worse aerodynamics - larger diameter wheel options usually come with LARGER tyres (width) --> worse aerodynamics, worse rolling resistance So at the end of the day it's not really the sidewall itself making all this difference, but other aspects that are usually (but not necessarily) linked with it. Of course it would be a different story if the OVERALL diameter of the wheels would change.
I noticed this dramatically on my E92 335i. It came with 19" wheels with the sport package. I put 18" forged wheels on. It was noticeably quicker off the line, turn in was quicker and bumps were less jarring. Not to mention replacements are cheaper on smaller diameter wheels and tires.
I've been watching your videos for years. I love the fact that you save me having to do the calculations etc on my own, as this is not easily available information. And based on this video I have decided not to put the larger wheels I had before buying my mg 4 on the car.
On my 3P I have gotten custom made 19x9.5 wheels weighining about 4kg less than OEM 20" per corner. Then it rolls on same type of tires,so much less rotational mass, much less unsprung mass. Better accelleration, better braking, better handling (less work for suspension). Then also the car is dropped quite a lot on KW V3 coilovers.
@@defnub he talked about aerodynamic front area of the tyres, lowering would reduce this but gains will be very small. less air underneath is also less drag.
Bingo! I’m pretty mystified why (apparently) people supposedly like huge wheels with rubber-band-thin tires! They kill your range/efficiency, they give a bumpier ride, they are more easily damaged by potholes, they’re noisier, and I personally don’t even see why people apparently think it _looks_ better!
You should make a video about what tire pressure to use. Lots of people believe that you gotta run the max psi the tire says for some reason. And mechanic shops do the same when installing tires. When I bought my truck new they set it to 40 psi . And it was supposed to be at 29.
Cadillac had something interesting going with the last gen CTS. You could get rims down to 17” but they scaled the sidewall down a touch and didn’t make the fender wells huge so it looks damn clean.
Really interesting data charts. The impact vs speed relationship seems to vary depending on car, with the model 3 having a much bigger (30%) difference at low speeds while the others having less difference at low speed. Seems to imply that something other than aero is strongly impacting the model 3 numbers.
As someone who has looked into the different Tesla’s to not dread the put-of-state drive to the in-laws, that table with the different Models and wheel sizes is priceless!
The 2001 mercedes E class avantgarde had 15 inch wheels and it still looks good today. I don't know why car manufacturers started making wheel arches you can fit a house in there. Silly.
You didn't say anything about why low profile wheels consume more energy. normally, I'd expect them to be stiffer and therefore have lower rolling resistance. What gives?
It would be interesting to see the difference in range between an aerodynamic wheel that is heavy (most likely cast) and a lighter wheel (flow-formed or forged) that is not aerodynamic in the same size and a + size. For example, a 16'' e-Golf wheel (aerodynamic, but very heavy) and let's say an Enkei RPF1 (not aerodynamic, but light).
Wheel weight is irrelevant in steady-state driving, it would have zero impact on range (OK, maybe a minuscule amount due to the curb weight being a tiny fraction higher...)
What about if you keep the same wheel size, but switch to a tire with slightly taller sidewalls, such as going from 225/40R19 to 225/45R19 with the exact same wheels? Would this approximately 4% increase in circumference also equate to better efficiency, or will the added weight of each tire negate it or even decrease efficiency?
One thing that strikes me: 9:19 you see the data summary. There you see a massive range impact difference for the model 3 at lower speed (i.e. 30,2% range impact difference when driving 5mph). That makes no sense. The data for Model S & X don't show that difference => Why?
Very unlikely. The energy to accelerate the wheel is far less than energy to accelerate the whole car. It's negligible. Also, are bigger wheel systems actually heavier than smaller wheel systems?
@@mitchellsteindler Simple math for me, smaller diameter take less energy to rotate. Thus can make greater total distance required. But downside for slower top speed compared to bigger diameter
@@mitchellsteindler It depends on the tire. Aluminium rims with thin profile tires might not weigh a lot, but put a smaller size rim and a very thick tire... it will definitely up the weight.
That as if you are driving in a straight line for a long distance. Narrower tyres are better in snow as well.Take the outer mirrors off..use cameras…govern 0-100kmh acceleration…who needs to get to 100 in 3 seconds..8 is fast enough..How often do you actually fill the car with 3 or 4 passengers? 95% of the time I am the only person in the car…less weight,less downward force on the vehicle more drag less efficiency…take out the rear seats, make rear seats portable,or just buy a two seater coupe two doors…take out all the fancy electronic aids apart from those that are used for the cars driving safety..and who needs to watch Netflix in the car? If one wants to surf the net during a break take an I pad with you..ah,in our household we could use a small 2 seater coupe and a 5 seater van…I don ˋ t mind driving the van.
Honestly, most public roads are not maintained well enough for 20+ inch wheels to be a good choice. It makes the ride quality worse and much more likely to get a flat tire or bent rim. Performance and aesthetic gains from large diameter wheels is not worth the other drawbacks.
They would presumably, yes, as compared to a larger size. I don't think you can run anything smaller than the 18" wheels on the Tesla though due to the giant brakes. Anything smaller would not have clearance. Theoretically you could fit smaller brakes but that would be seriously compromising driver safety trying to chase energy efficiency which is not advisable.
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I'm guessing 17 inch wheel wouldn't be possible to put on Tesla Model 3 Performance because of the brake disc size.
Nice vid as always buuuut: I'd like to know the reason why there is a difference between different diameters. i.e. the reason of the graph at 7:44. I saw your clarification but i can't understand. If it is only a matter of aero, why the gap in efficency gets smaller increasing the speed? (9:20) I mean, and please correct me if i am wrong, the higher the speeds (linear or angular) the more relevant the aero. What am i missing? And, why data from Model 3 are so different from X and S? X and S numbers are not weird to me but damn, i can't conciliate with thoose of the Model 3 xD
It's not the actual diameter of the wheel, it's many factors associated with that diameter. A performance tire has more grip, therefore more rolling resistance. The SAME wheel in a larger diameter weighs more and is more rotational mass. If the larger wheel comes with a wider tire, more rolling resistance again. In other words, the combination of the wheel and tire are the true factor, not just the diameter of the wheel. I can assure you that you can find some taller wheel combinations that will yield better fuel mileage if the wheel is lighter in weight, skinnier, and you mounted a Low Rolling Resistance style tire on it. However, in *general*, the larger the wheel diameter, the more likely to have a performance tire (sticky) and the more weight and more rolling resistance.
My opinion/ guess is that the air flows around the inside of the rim differently at different speeds. Often at high speed, a bubble of air will form in a space, reducing aerodynamic drag.
There's another very clear benefit of smaller rims (= lighter rim): quicker acceleration!! This should not be underestimated, because we are talking about unspring weight. Excellent video by the way :-)
Don't own an electric car, but need to get new set of tires for my full size pickup. Thanks to this video, I now know what to do about wheel size and tire profile. Thanks!
We use to think: I would pay more and get bigger tires because they look cooler, now we think: I’m gonna get the bigger tires “to show people that I don’t have range engziety” lol
What I was hoping to learn from you was the difference in 1) mass of a large wheel with low profile tire vs. small wheel with high profile tire; and 2) the angular momentum difference in the two.
I always watch these videos to the end. Most of it goes over my head but I'm comforted by the idea that if I really needed to figure something out, there's a formula for it. Great video. Save the planet with tires.😎
I didn't get why larger rims decrease efficiency. I mean the total diameter is the same (rim + tire), so what changes? Does the width of the tire/rim also increase with increased rim diameter?
@@dwt51 Good point, because so often the average driver in a typical car (ICE or EV) has the tyres under pressure more often than not. It’s one of the best things about a good TPMS system, which nags the driver to top his tyres up. People are generally lazy when it comes to such things.
When it was time to get new tires, I went from 18" wheels to 16" rims. Lighter, when better acceleration and braking and softer ride. I make fun of the dealer when he tries to sell me on a car because of the size of the wheels. I say, " what are you, 16 years old?"
@Art Uro That's because a fat, low-pressure tire has a lot of rolling resistance while a narrow high-pressure tire has very little rolling resistance. It doesn't have anything to do with mass. The mass of a wheel only affects the energy required when accelerating. And electric cars have regenerative braking, so even if the tire has more mass, then you get more energy back when decelerating.
As someone who works in the field, i would caution against a few conclusions. The 'C' term in the road load curve is not just aerodynamics, tire RR has some 2nd order effects. So you cant just compare aerodynamics in a vacuum when going from one wheel size to the next. Additionally, one somewhat decent metric for comparing wheel aerodynamic performance is the opening area. You could make a 20" wheel with a cover and it would be comparable to a 17", but generally thats a no-go from the styling department. That's why, in general it's harder to control aerodynamics on a larger wheel diameter but it certainly can be done and you'll find wheels that are good and bad regardless of size.
Sorry Charlie, Not entirely true- because you can’t control the aerodynamics of the BACK of the wheel- it DOES make a difference even though less than the front.
@@FutureSystem738 we are talking diameter here, not width. Width has a direct impact on frontal area and would be reducing your Cd if you could maintain the same drag hange point to change point.
@@charliewilson9062 I’m very well aware you’re talking about diameter. I should have used the words “inside” and “outside” of the wheel rather than front and back. There is still aero drag on the inside of the wheel, even though it’s significantly less than the outside where an aero cover can be installed. (It’s one reason some manufacturers like Tesla try to make the floor pan as flat as possible. There is still air moving under the car, and aero drag, and the inside of the wheels is all part of it.)
I have a Lexus Fsport IS350, I just bought 17's for my winter set (vs. the 18's on the summer/spring/fall set) the combination of taller sidewall, narrower section width (225 vs 255), and different tire compound completely change the handling characteristics, and as a result, my confidence in it's handling in the winter. I expect they will get better as the temperature drops, and I'll be experimenting with tire pressures, but I can't wait until spring comes when I can get my wider set back on. Just something worth considering when having a wheel & tire discussion.
I wonder how the weight of the wheel factors in to all of this. Does the weight of the wheel make a difference at a constant velocity or does that only effect the amount of energy it takes to change the rate of speed of the wheel? So if you upgraded to a bigger wheel that is lighter than the smaller wheel, is that enough to off set the aerodynamic losses with all other factors equal? 🤔 Sounds like some experimenting is in order. Great video👍
Interesting video and nicely explained. One thing that would be interesting though is the difference of weights for larger wheels vs size. For example would a 19" wheel that's 1kg lighter than an 18" have much affect on range? I know it's more acceleration but over the time of a full battery surely it's of some significance that could maybe allow going bigger and have less of an impact in range?
It's all about aerodynamics, it has almost nothing to do with weight. A slightly lighter/heavier wheel would change the inertia to overcome while accelerating, but do nothing steady-state.
Would've been interesting to also look at total wheel and tire package weight differences. Usually smaller wheels are significantly lighter, if I'm not mistaken.
The tyre would be significant more heavy assuming that the total circumference must be nearly the same. Depending on material use for the wheel and which has more effect...extra weight of rubber against less weight of the metal.
In general, you are correct with your results in the sense that for a given wheel dimension, a smaller rim is more efficient. However, small tires in general are very inefficient. Because of this we see wheel sizes increasing. The tire with a small outer diameter has to spin faster for a given speed, because the radius is smaller, it gets more deformed --> less efficient. So a very large tire diameter is a thing increasing the efficiency! Just look at a BMW i3, a car that has been optimised for efficiency. There, the tire diameter is very large, the car has 21" rims as standard. Another benefit of that is, that you can make the tire even slimmer, reducing the area of the tire exposed to air resistance further. So look out for an electric car that can fit a very large outer diameter wheel if you’re searching for maximum efficiency. By the way: Those great looking rims with slim spokes are very inefficient, too. The standard M3 rims are very closed, creating less drag. They don’t look that cool, though...
checking BMW i3 base model specs from my local BMW web site: Tire = 155/70 R19 84Q, Rim = 5Jx19 LM so maybe those 21 inch rims you mention are some sort of option.
That was a VERY weird and unusual episode... 🤔 When looking at engineering explained, you typically can sit down and relax, being pretty sure that the perspective is going to be scientific. But here you are analysing the impacts of physical things, but when it comes to wheel diameter, you just basically say “Tesla says”! 😳 I’m not saying that Tesla is wrong, and I don’t hate high sidewalls, on the contrary - I love high sidewalls! (Yes, I am that old.) I like the tire to be/remain the mechanical vibration isolation that the tires were invented to be! And I like formula one cars to use wheels with high sidewall-tires! So I’m really sad about the new F1-regulation change, applauded of coarse by the tire manufacturers that have been pushing the meme “big wheels/low tires is better/cooler/sportier” for so many years. 😕 But - you just can not just buy the numbers regarding range, directly from Tesla! Other people play it like that, but not you! That is not scientific! The range depends on so many things! Tire pressure for one. It just is so unscientific to talk about diameter of the rim so people with less knowledge mistakes it as something that’s proportional to the circumference of the wheel with a tire on. So please be your normal self and go into the physics! Don’t just quote claims from Tesla! If Tesla’s right regarding the range being almost inversely proportional to the rim diameter (even when to tires outer diameter is unchanged) then go into the WHY. Tell us about sidewall losses that becomes higher when the sidewall is exposed to a higher degree of relative deformation. Or just ignore me. 😀 I am sometimes unnecessarily negative. ☺️
I'm pretty sure he used that data because a) it's available online b) it's very likely measured data c) it's pretty much impossible to calculate that stuff by yourself. You'd need to run very advanced CFD simulations on a very accurately 3D modeled car to get the drag data. Then you'd need to do some sort of physics simulations on how different tire sidewall heights affect range. It would probably take weeks of full-time work and very expensive software and hardware to be able to calculate this stuff. So why not use data that is already out there? I don't know about the USA, but at least in my country, false advertising is illegal. So if Tesla is advertising those range numbers on different wheel sizes, I'm pretty sure they aren't lying. And the most important piece of data there isn't the range itself, but the difference in range between different wheel sizes.
I don't understand Jason leaving out so much information in this video. He talks about wheel diameter but fails to mention the wheel width for the different wheels. Often times the larger diameter wheels are for track performance and thus have wider wheels. Like the Taycan has rear wheels of 19" that are 265mm, 20" that are 285mm and 21" that are 305mm. Also the tire stickyness may change on what's fitted for the different rim sizes. Seems like a bit simplistic of an analysis to me.
I am absolutely delighted that Jason has built several videos from one pothole destroying his odd-sized Tesla wheel.
Gift that keeps on giving!
i was thinking the same..
Somehow he has to get the money back.
Question: shouldn't the comparison be made based on the rolling diameter of the tire rather tha wheel diameter? If the smaller wheel/larger tire diameter combination results in a larger exposed tire area, the some of the gains will be reduced or negated.
😆😆
**CLARIFICATION!** Why do bigger wheels mean worse efficiency, when the overall tire diameter remains the same? This comes down to aerodynamics. A 20" wheel will cause more of a disruption in airflow than an 18" wheel. That's why Tesla (and others) uses aero covers on their wheels (Car & Driver testing showed it gives about a 3% efficiency bonus at speed). The smaller the wheel, the more of the side profile of the wheel & tire is perfectly flat (the tire is flat, the wheel is open: more tire = more flat area, less open area). Ideally, you'd have just a plain, solid sheet for the wheel, but obviously that's not idea for brake cooling. Wheel covers are today's common compromise as they have some airflow, but minimal.
Let's bring back big sidewalls! Watch till the end to learn how fat sidewalls will save the planet. Car community doing their part. 💪😂
Is this applicable to internal combuation cars, I would like to know if I can save the environment too 🤔
Edit: Clarification already did
Can you do a white board video on how much range you would lose by ricing a Tesla? Spoilers, Canards, 45 degree camber ect. 😂
Why does bigger wheels by itself hurt EV range or gas mileage?
I just thought of this. When range testing different size wheels in real life, do people account for the speedometer being slightly off due to the size of the entire tire and wheel?
@@mai_kul If I was range testing a vehicle I would NOT use the speedometer. The range tests are either done with a rolling road or other means of monitoring speed and distance.
I remember a race car engineer saying the ideal wheel size is the smallest you can fit around your brakes.
That's why Tyrell ran a 6 wheel F1 car. It worked so it was banned.
Makes sense to me
@@andrewsaint6581 he didn’t run that for wheel size. He ran it because it increased the overall contract patch of his wheels, which gave him more grip.
@@andrewsaint6581 the 6 wheel car had 4 front small wheels to have better grip and better aero on the upper part being flat but has nothing to do with side walls
@Tamara Maschan true, f1 cars try to use small wheels to some extent. I had a similar experience i raced my stock 325 vs a stock 325 but with big wheels and in the 1/4 it did a small difference
It's interesting to me that standard wheel sizes have been increasing over the years from all car manufacturers. It seems like it was just for looks, not for ride quality or efficiency.
On electric and heavy vehicles some of has to do with brake disc size, bigger rims means more room for bigger discs. Another part of it has to do with handling on the limit in heavy vehicles, like when performing evasive maneuvers like the dreaded "moose test" etc. But you are partly right, on some cars it really is just for looks. And many customers would do well NOT to tick those bigger wheel options when ordering a car, I certainly don't.
The size of the vehicles increases too. Also mostly for looks. People drive around in Tundras which are legitimately scarily large with nothing except a handbag with them. They think it looks cool.
The original premise was handling, as in cornering
@aluisious that's part of why Bolt EUV is more popular than EV, a little more back seat, but 6 in longer
Larger tires and wheels also cost more to replace.
What should decide wheel size? Brakes! The brakes need to be large enough for the performance of the vehicle and that alone should decide the wheel diameter.
This settles it. I'm calling my crush and telling her that 2 inches less is 15% better, I hope that finally gets her to date me.
🤣🤣🤣😂😂
15% increased thrusts per minute, resulting in 15% faster finishing time. Idk man that still sounds like a bad thing for her
jokes on you, i already told her 0 inches is 100% better
Shorter, but thicker.
So you sexually identify as a model 3?
understandably so.
Big wheels are pretty much worse all around imo. Without watching the video first, tire are usually more expensive, have worse ride quality, more prone to curb rash and bending a rim on a pot hole. Basically worse in the real world.
Yeah but they look cooler tho.
Well wider tyres give you more grip.
I despise “wagon wheels”. It’s really bad when you put them on a ‘70s/‘80s land yacht and ruin the smooth ride and handling they’re famous for.
yeah, i've been looking at swapping the brakes on my car so i can fit 15s. it's nice to not worry about potholes and curb rash, plus better rotation in corners with the skinnier tires. efficiency is cool too, i guess.
@@SoulTouchMusic93 I don't like the look of the slim tires on huge rims.
Board: *says 0.6*
EE: "nearly ONE percent!"
That's some healthy rounding right there!
It's Apple style marketing! This video Jason made is the newest video he has ever produced!
More than half at least.
Try it yourself in any program. Even Excel, round(0.6) will give you 1.
"that's nearly 1.7 times the real value" :D
Tire and wheel size has increased substantially in the last 30 years. People may not remember this, but cars like the 1990 Honda Accord LX and the 1989 Camry (base version) had 14 inch wheels and used 185/70R 14 tires. As indicated by the 70 aspect ratio, those cars had wide sidewalls and the ride they provided was fine. When I bought a new car in Sept. of 2017, I bought a 2017 Camry LE rather than the 2018 model (which was already being sold) in part to avoid the new dual clutch automatic transmission, but also to get the smallest possible wheel size (16 inches) and the largest aspect ratio (65) I could. Even the higher priced 2017 Camry models forced you to get larger wheel sizes. An article in a car magazine I read several years ago included an interview with an auto executive who was asked why manufacturers kept on using bigger wheels despite the various engineering drawbacks, and he replied that it was largely done for styling reasons.
the main driver, I think, of those "styling reasons" is EU pedestrian impact standards that effectively require a very high hood-line, which in turn causes that "blocky" look with tall fenders, which look silly without big wheels. They're trying to make the wheels proportionate to the chunky look of everything else that the pedestrian impact standards force.
I know this is two years old now but hopefully by now you’ve realized the Camry has a traditional slush box 8 speed auto, not a dual clutch as you stated. Sorry it just triggered my inner autist and I had to comment.
Smaller side shoulder of a tire improves sharp steering in contrast to suspension "ride quality". Today middle driver prefers driveability to comfort. Just a business.
This is true. But also follows that wheel and tyre size *decreased* substantially from 1910 to 1960. Wheels went from 36" on a 1910 car, down to 27" or so on a 1915, down to 21" or so on a 1925 and then down to 18" to 17" to 16" or so in the 1940's and then an even smaller 14" to 15" became the fashion in the late 50's and early 60's, to allow for a lower, sleeker profile of the overall vehicle. These 13" and 14" carried through to 1980's economy cars as you say, but then wheels started to grow bigger again as increasingly low profile radials were developed (starting with radials less than S or standard 82% profile, first coming out in the late 60's).
The exotic 16" "low profile" 205/55 R16 that was once the preserve of a Porsche 911 front tyre in 1985 is now the standard tyre on the most base model Toyota Corolla, and the 225/40 R18 that was so exotic when it was a Ferrari 355 front tyre in 1998 is now the standard tyre on a higher trim level Corolla!
As cars (unfortunately) get taller again more like 1930's cars -- reverting the change to low, sleek, more aerodynamic designs of the 1970's and 1980's -- it makes sense that wheels would get larger again, even if only for stylistic reasons.
To: Tassie Lorenzo: Thanks for your informative comment. I was not aware of the historical information that you provided. @@TassieLorenzo
I never realized the impact of intentionally going with 16” cheap tire option rather than the 18”. I’m able to get 40.5 mpg average on a 2.0L focus manual. Watching this video really makes me think that tire choice has a much larger impact on mpg than previously thought.
Hence the reason why the Prius always had tiny wheels - 15". Cheap stuff that was good stuff.
The Geo Metro had 13 inch wheels!
And it also makes tires cheap. A set of brand new michelins for my prius was $450 installed
I notice the new MG electric cars have good range and small wheels too.
Great video. When moving between the wheel sizes, the bigger wheels may be heavier. If so would that make a difference? Wondering if a 235 tire in 18 stock wheel is more efficient than 235 tire on a lighter (perhaps forged) 20" wheel.
@@5roundsrapid263 13" was a regular size for many cars in europe. My mk1 and mk2 golfs both have 13's
Sweet, so my 37" tires on 17" wheels for my truck is really saving the planet. Nice
Assuming those tires are still within the profile of the vehicle. 👍
And it looks right
Lmao sounds like Alberta
Thanks for doing your part! 😂
@@iNick90 ...and weigh as much as the stock tire wheel combo.
For all cars, you just notice it more on electric.
Wheel weight also has a lot to do with it (which EE has already made a video about). I had aftermarket 20" wheels (at 35 lbs / wheel) installed on my stealth Model 3 Performance, and my energy usage increased to ~270 wh/m. They looked awesome, but I've been doing a lot of road trips lately and wanted better range. I recently purchased a set of the 19" Tesla sport wheels (at 25 lbs / wheel), and my energy usage is now back to ~240 wh/m - much better :-)
could you link the video on wheel weight you mentioned? Thanks
What is a stealth Model 3 performance?
@@navid8276 It's a Model 3 that has the big performance motors, but the regular brakes, no spoiler, and no track mode. It's basically a Long Range with bigger motors, so stealthily as fast as a Performance model, but none of the change in looks.
they should call it model 3 BIG MOTOR then 😅
The weight of the wheel will have _zero_ impact on steady-state range. The only time you'd notice it is when accelerating that mass up to a certain speed, ergo, "road trips" would be the _last_ place you'd ever notice a mass difference.
Hope you read that. I made allot of calculations for my 3.0 Continental in order to understand how tire pressure is determined. - wanted to use non standard 235/50/19 winter tires and keep rolling resistance, contact patch, etc. to spec. Turned out the required pressure is 2.4 bar - the same as the stock pressure of the stock size 235/50/18 - see why below.
245/40/20 - 2.7 bar cold pressure - ~3.7% sidewall deformation
255/45/19 - 2.3 bar cold pressure ~ 3.8% sidewall deformation
Calculation:
1/2 of axle load is divided by pressure, this gives area of contact patch;
Area/width of tire gives length;
1/2 length of contact patch is used to solve right angle triangle as one side, second side - hypothenuse is the non deformed radius and the third side is the effective radius of the loaded tire. Substract r-eff from r-nominal you get amount of deformation in mm. Find percentage from sidewall height and that's your percentage of deformation.
If you play enough, you'll find out that taller tires allow for less deformation especially if they are tall and wide.
For instance, a 2005 Mustang GT on it's stock 235/55/17 would deform them less than 2% at 2.2-2.4 bar cold.
Allot of info can be drawn from this simple calculation.
And btw, your added air drag calculation is not correct. A wheel has Cd of 1, so your 0.03m2 should be included roughly 4.5 times in the drag of a 0.22 Cd automobile thus contributing to allot more drag than you came with.
Best regards!
P.S. you seem to never react to my comments.
Me: **Looks in bank account**..........**Starts affixing grocery cart wheels to car**
Extremely underrated comment 😂
If TH-cam had a decent algorithm youd be a top comment
I would like to know the impact narrower tires have on braking distance.
All aspects of performance. Braking, acceleration, handling. How big a tradeoff are we willing to make for range vs performance?
And also the performance changes that would come with larger sidewalls
It has very little effect. Grip isn't changed much, as for any given tire pressure the contact area is the same regardless of tire width.
@@joby602 how can contact area be the same regardless of width? The wider the tire, the more contact area, no? I get that aspect ratio beyond a certain point isn't going to take away from performance. What is the best for each of these cars for performance, safety, and economy? It depends.
@@joby602 that is very much not true. Contact patch is roughly circular, small changes in the radius of the contact patch result in large changes in area.
From my own anecdotal experiences, I replaced 205/75/15 tires with 255/60/15 tires on a RWD car. With the 205s I was very easily able to break the back tires loose and do a burnout on dry, clean pavement. With the 255/60/15 tires it was not easy to break the back tires loose, I simply had grip. Admittedly these were not the same brand of tires, but they were targeted towards the same mid-priced market.
Oh yeah!!! I love this video, Never got to liking Low-profile wheels. Yes they react faster but then again, more expensive, louder, stiffer and doesn't protect rim.
And you can't run white walls.
Yeah that’s why I loved the 18” wheels in my 2008 Bullitt Mustang. Nice fat sidewall. Looked nice, rode nice and protected the wheel better.
There is more to it than that, a wider tire on the front will give you worse turn in. There is a fine balance and a few other things he doesn't cover in this video that are a major part of efficiency and performance.
Make sidewalls great again!
Make sidewalks great again!
Sums it up perfectly. “Bring back big sidewalls and get rid of silly low profile tyres!” Win, win, win win!
I do not understand the absolute obsession that many people have with ultra low profile tyres.
They waste less rubber
they just need to reverse the options pricing. "Oh you want the 18 inch wheels? That will be an extra 1000$" "But it comes stock with 20s" "I know. But the 18s will increase your range by 15%".
Of course that argument has no chance against "I'll take the most expensive option please. Spare me the details"
@Peter Evans You are talking about larger diameter tires and what you say is true, but I think the video was about the same overall tire diameter but smaller rims.
So... why does this happen? Why are smaller wheels more efficient? That's what I actually expected you to talk about. The rest of the physics is quite intuitive
Agree. You used Tesla's provided coast down curves, but would love an explanation and the math behind why the curves are different. Is the tire diameter actually slightly different and that is the reason? Or is the weight of the tire/wheel combo different and that accounts for the difference?
@@schmke I think its because larger diameter wheels usually have greater width? I don't know. Yeah, Jason should have explained this!
More of the mass of the wheel + tire is near the outer edge of the wheel. This requires more torque to turn the wheel with more mass further from the center of the wheel. Less efficient
It’s because smaller wheels have less mass and thus less inertia
Smaller wheels have less mass, less mass takes less energy to move
Recently switched from 18 to 19" wheels on my Model 3 and I thought I was going crazy or my battery was just degrading after my range went almost exactly from 299 to 284 and I noticed higher wh/mi when driving so this video provides great clarity and closure haha.
Did you change back to 18" wheels? I'm thinking of going from 19" to 18"
It would be wonderful if someone did an analysis on various OEM and aftermarket wheels and tires to show how they rank for range efficiency. That way, people could compare them and make informed decisions. Using that along with average tread miles on the tire would be wonderful. This is the kind of stuff I wish Consumer Reports would focus their money on.
I read a guy put 15 inch show tires on his Bolt and gained about 20 miles of range. The snow tires were not even low rolling resistance, where the original tires were. I think they come with 17's.
Well, Forza models this well since increasing rim size lowers the car's stats slightly
Not trying to kill the joke but, that's because of rim size, the bigger the rim, the heavier.
but in forza world, burn outs happen with rev hangs 🤣🤣
I have the best Tires. My wheels go around, like no other ones do.
Many people say this about them. Great tires.
As an ME, I absolutely LOVE your whiteboard work. Such a great channel. Cheers!
7:50 Changing tires at 75mph. You, sir, have one hell of a talented pit crew.
still doesnt really explain why larger diameter wheel leads to lower efficiency
As someone that hates 20" wheels on anything, I am glad that math supports smaller wheel sizes.
20's on something like an Escalade look tiny.
This makes me glad I went for the Tesla Model 3 Stealth P3D-!
That is a great reason not to make Escalades.
you can fit bigger brakes. thats about it.
I quite like the factory 20s on my r35
"Lets say you have a very slim tyre, 205"
- cries in 175
Cries in 165 :(
I have 2 sets, the summer set is the "big" 15 inch 185 tires vs the 13 inch 165 ones on my winter set.
I had 155s on my Mirage
BMW i3 - 155/70-19 and they're only made by Bridgestone
145/80-10 Austin Mini . Winner takes all until Chang-Li qualifies as a car
In Swizterland, we have a lot of those BMW i3 cars. I meet some everytime I go out. I'm always impressed how narrow their tires are when you compair it to 90% of the rest of the market. This is at least one thing that BMW made right on this car.
Base i3 wheels are 155/70R19. Definitely narrow, but also much larger outer diameter than usual. Really unusual setup.
They look really cool if you ask me. Reminds me of old Beetle-wheels :)
bmw could have given a smaller wheels with wider tyres and still got the same aerodynamics benefits..
@@superchargedpetrolhead I don't believe it no. The wideness of the tire is the thing the wind sees when it hits frontal under the car. It can be channeled to some extent. But there is always some air that will frontal attack the wheel base.
You can look at eco-protoype racing. The tires are nearly roadbike like.
Last week I swaped the summer for the winter wheels. 19×10 285 45 R19 summer to 235 65 R17 winter. The consumption dropped down about a liter on 100km. Range went from 950km to 1150km. For people who like units in a stone×leg per evening style, that's a difference of 4 miles per gallon and about 120 miles more range! On a X5 Diesel.
My 1987 Subaru GL Wagon had 13 inch wheels. I've never seen those before or since. I wrecked it in 93, put it between two trees and straightened it out with a come-along. Straightened the radiator mounts and a fender with a hammer, slapped in the new radiator and a headlight assembly and drove it another 5 years.
I would like to know what effects driver weight might have on range. To keep math simple while using weights within the reasonably expected range at your local Walmart, you could use a 160lb individual versus a 320 lb individual.
most people who shop at walmart aren't going to be driving a tesla
lol
@@Blox117, that's like saying most people who shop at Best Buy aren't going to have three nipples. Most people aren't going to be driving a tesla, regardless of where they shop.
@@Blox117
Where else would you go?
@@---cr8nw well it was mostly a joke about economic status and wealth, not statistics
@@Blox117, well.... joking about people's economic status and wealth.... classy.... You seem like a person I wouldn't want to know.
On the upside, you don't have to worry about your wheels getting damaged by potholes since they're smaller sizes
"your"
you are wheels
I wouldn't be so sure of that
I ruined a 16inch alloy rim and its tire on a pothole and was only doing about 25 or 30. Wasn't even a monster hole
Is that because smaller wheels don’t go as far into the pothole as big wheels?
Your theoretical presentation is very impressive. Last year I went from a 19 to 20" wheel on my Model 3 Performance. My daily commute is approximately 100 miles round trip. For the time being I get to enjoy carpool lane access in my state driving solo, so I'm able to cruise at about 75 mph. I've noticed only a 3% real world increase in battery usage.
What’s the point to increase tires then?
That's +10 miles of range. Imagine going down to 18"
I used to deliver tires and wheels for a wholesaler/distribution company, and there’s another reason for loss of efficiency with larger wheels. In general, they weigh a hell of a lot more and thus have a lot higher rotating mass which is terrible for overcoming inertia, both for accelerating and for braking. You have to pay a lot for a lighter weight, larger diameter wheel, and if you paid the same “lot more” for a smaller diameter wheel, you’d still get better efficiency and performance.
Tesla's range graph is based on their OEM 18"-21" wheels which also have increasing weights as diameter increases. So the drop in range can be due to increased unsprung weight and not necessarily increases diameter. So if that is the case one can install larger aftermarket wheels (forged or flow formed) that are lighter than the smaller OEM wheel, and possibly achieve the same if not better range.
+1
Wheel weight is irrelevant in steady-state driving, it would have zero impact on range (OK, maybe a minuscule amount due to the curb weight being a tiny fraction higher...) As Jason said in the comments, it's 100% aerodynamics (poorer) of larger wheels of a similar design.
6 inches of groudn clearance? *laughs in honda Fit
groudn
Right. I'm constantly scraping mine on my driveway
110 mm is about as low as it gets on any car with stock suspension that's on the road, and that would be a first gen bmw z4, but a Honda fit at 130mm is still far lower than a porsche 911.
My yaris is basically slammed from old suspension when there are more than 2 people in the car. Scrape city is not a fun place to be
After driving a Hyundai Accent, it makes me want my next purchase to be a jeep
Remember when cars had 14" and 15" wheels? Pepperidge Farms remembers.
I remember. I just need to look at my garage, family commuter life
I drive a Hyundai Getz, 14" rim club represent!
My truck has 15" wheels and 32" tyres
My swift has 14inch steelies 😂
I've got a '84 V Jetta Gli coupe with the 14" Snowflake wheels on 175/R14 60 tires, and the ride is rough as it is. I don't want to imagine how rough it would be with 16" or 17" rims with low profiles! Low profiles are the high-heels of the automotive world: looks great, but impractical.
This is an extra reason. I want to get away from low profile because I drive on typical city roads a lot!
This video couldn't have come at a better time. I was in the process of buying new wheels for my M3P. Great to see some factual information to support my decisions, thanks for the informative video!
Tell me you're going to teach engineering? You're an outstanding teacher.
Bigger (& wider) wheels will very likely increase the stress on the suspension components and the wheel bearings. I kept the same size on my car but searched for lighter wheels to reduce the unsprung weight. Excellent video!!!!
Typically, the wheels are not wider and the tire width is the same. As long as the offset is is the same, even a wider wheel would have no impact on suspension "stress". It's strictly a "+1" or "+2" aspect ratio change for looks alone, nothing else.
Thank you for the great explanation :D
Hope you are doing well in these weird times ;)
Greetings from Norway
Yay for Norway. Big time EV leader.
Given the popularity of SUVs/Crossovers, especially those with larger wheel base intended for off-roading, I'd be curious to see your analysis of off-road tire efficiency.
The dissertation on the separate effects that go into the resistance is correct, but there is no real mention of WHY a taller sidewall should be more efficient.
As a matter of fact, ceteris paribus, a taller sidewall is LESS efficient. More rubber that goes through an hysteris cycle. Proof of this is that taller sidewalls are more comfortable: that's because they deform more under load and we all know DEFORMATION OF HYSTERETIC MATERIAL = ENERGY DISSIPATION.
Also: a lower aspect ratio tyre weighs LESS than a higher aspect ratio, if the width is kept constant. The additional weight of the rim does not offset this difference, usually. The overall diameter stays constant, as you showed, so there is no big difference in rotational inertia, too.
What you mixed here are different things:
- lower sidewalls imply larger rims/spokes ---> worse aerodynamics
- larger diameter wheel options usually come with LARGER tyres (width) --> worse aerodynamics, worse rolling resistance
So at the end of the day it's not really the sidewall itself making all this difference, but other aspects that are usually (but not necessarily) linked with it.
Of course it would be a different story if the OVERALL diameter of the wheels would change.
I noticed this dramatically on my E92 335i. It came with 19" wheels with the sport package. I put 18" forged wheels on. It was noticeably quicker off the line, turn in was quicker and bumps were less jarring. Not to mention replacements are cheaper on smaller diameter wheels and tires.
I've been watching your videos for years. I love the fact that you save me having to do the calculations etc on my own, as this is not easily available information. And based on this video I have decided not to put the larger wheels I had before buying my mg 4 on the car.
On my 3P I have gotten custom made 19x9.5 wheels weighining about 4kg less than OEM 20" per corner.
Then it rolls on same type of tires,so much less rotational mass, much less unsprung mass. Better accelleration, better braking, better handling (less work for suspension).
Then also the car is dropped quite a lot on KW V3 coilovers.
If you lowered the tesla with 18in rims would you gain mileage?
Did you even watch the whole video mate?
The answer you were looking for is - yes.
Best to go donk with your tesla, go big or go home
@@jeeewhyyypheee yes but he didn't go into lowering the vehicle, he stated the ride height was 6in off the ground
@@defnub he talked about aerodynamic front area of the tyres, lowering would reduce this but gains will be very small. less air underneath is also less drag.
Bingo! I’m pretty mystified why (apparently) people supposedly like huge wheels with rubber-band-thin tires!
They kill your range/efficiency, they give a bumpier ride, they are more easily damaged by potholes, they’re noisier, and I personally don’t even see why people apparently think it _looks_ better!
You should make a video about what tire pressure to use. Lots of people believe that you gotta run the max psi the tire says for some reason. And mechanic shops do the same when installing tires. When I bought my truck new they set it to 40 psi . And it was supposed to be at 29.
What about the unsprung weight added from bigger wheels, how does it affect performance and range ?
It doesn't. It affects ride comfort and grip over bumps, but not range.
It will affect range in stop and go traffic. It takes more energy to accelerate with more weight.
Interesting to know that weight won’t impact the range? Can you explain
*BRING BACK 14" WHEELS...* and white walls too, why not?
My 1st gen insight has 13 or 14" wheels. I got "only" 65 mpg the other day without really using the hybrid drive.. because I had low tire pressure.
White/yellow lettering is making a comeback already. I want to see more of it!!
Cadillac had something interesting going with the last gen CTS. You could get rims down to 17” but they scaled the sidewall down a touch and didn’t make the fender wells huge so it looks damn clean.
15s and some sidewall are perfect
I had a car with 12-in rims. Talk about hard to find tires for it.
Really interesting data charts. The impact vs speed relationship seems to vary depending on car, with the model 3 having a much bigger (30%) difference at low speeds while the others having less difference at low speed. Seems to imply that something other than aero is strongly impacting the model 3 numbers.
electric motor impedance
As someone who has looked into the different Tesla’s to not dread the put-of-state drive to the in-laws, that table with the different Models and wheel sizes is priceless!
The 2001 mercedes E class avantgarde had 15 inch wheels and it still looks good today. I don't know why car manufacturers started making wheel arches you can fit a house in there. Silly.
You didn't say anything about why low profile wheels consume more energy. normally, I'd expect them to be stiffer and therefore have lower rolling resistance. What gives?
It would be interesting to see the difference in range between an aerodynamic wheel that is heavy (most likely cast) and a lighter wheel (flow-formed or forged) that is not aerodynamic in the same size and a + size. For example, a 16'' e-Golf wheel (aerodynamic, but very heavy) and let's say an Enkei RPF1 (not aerodynamic, but light).
Wheel weight is irrelevant in steady-state driving, it would have zero impact on range (OK, maybe a minuscule amount due to the curb weight being a tiny fraction higher...)
What about if you keep the same wheel size, but switch to a tire with slightly taller sidewalls, such as going from 225/40R19 to 225/45R19 with the exact same wheels?
Would this approximately 4% increase in circumference also equate to better efficiency, or will the added weight of each tire negate it or even decrease efficiency?
Your tires may rub against the wheel wells during sharp turns.
One thing that strikes me: 9:19 you see the data summary. There you see a massive range impact difference for the model 3 at lower speed (i.e. 30,2% range impact difference when driving 5mph). That makes no sense. The data for Model S & X don't show that difference => Why?
Thank you for being the one person on youtube who understands car and tire physics!
BMW I3 owners have just entered the conversation...did someone say pizza cutters? Lol
Alot of them were changing their 20s that come on the higher end model to the 19s because the ride was so harsh.
1:39 There is a missing component : (4) the effect of a wheel cover on the Tesla Model 3 with 18" compared to the 18" / 19"/ 20" with no cover
How does the mass of the wheel and moment of inertia contribute to amount of range loss vs merely a size increase? Could it be more due to this?
Very unlikely. The energy to accelerate the wheel is far less than energy to accelerate the whole car. It's negligible. Also, are bigger wheel systems actually heavier than smaller wheel systems?
@@mitchellsteindler Simple math for me, smaller diameter take less energy to rotate. Thus can make greater total distance required. But downside for slower top speed compared to bigger diameter
@@mitchellsteindler It depends on the tire. Aluminium rims with thin profile tires might not weigh a lot, but put a smaller size rim and a very thick tire... it will definitely up the weight.
The torque ratio has more effect.
Inertia is M*R^2. Here, mass difference would not make much difference as compared to the diameter.
That as if you are driving in a straight line for a long distance. Narrower tyres are better in snow as well.Take the outer mirrors off..use cameras…govern 0-100kmh acceleration…who needs to get to 100 in 3 seconds..8 is fast enough..How often do you actually fill the car with 3 or 4 passengers? 95% of the time I am the only person in the car…less weight,less downward force on the vehicle more drag less efficiency…take out the rear seats, make rear seats portable,or just buy a two seater coupe two doors…take out all the fancy electronic aids apart from those that are used for the cars driving safety..and who needs to watch Netflix in the car? If one wants to surf the net during a break take an I pad with you..ah,in our household we could use a small 2 seater coupe and a 5 seater van…I don ˋ t mind driving the van.
Honestly, most public roads are not maintained well enough for 20+ inch wheels to be a good choice. It makes the ride quality worse and much more likely to get a flat tire or bent rim. Performance and aesthetic gains from large diameter wheels is not worth the other drawbacks.
Soooooo... Bigger isn’t always better?! You should tell that to my uncle!
All jokes, your friends at Business Explained!!
Is this a joke about how your uncle is packing schmeat?
Would a 17 inch wheel increase range? Great video and as always, great information.
They would presumably, yes, as compared to a larger size. I don't think you can run anything smaller than the 18" wheels on the Tesla though due to the giant brakes. Anything smaller would not have clearance. Theoretically you could fit smaller brakes but that would be seriously compromising driver safety trying to chase energy efficiency which is not advisable.
I'm guessing 17 inch wheel wouldn't be possible to put on Tesla Model 3 Performance because of the brake disc size.
0 inch wheel = maximum efficiency
@@Blox117 limf(x) as x->0^+ = infinity.
@@PringleSn1ffer Custom rotors built on the axle instead of each wheel would solve that issue. Upgrade by using greater # of pistons in calipers.
Nice vid as always buuuut: I'd like to know the reason why there is a difference between different diameters. i.e. the reason of the graph at 7:44.
I saw your clarification but i can't understand. If it is only a matter of aero, why the gap in efficency gets smaller increasing the speed? (9:20)
I mean, and please correct me if i am wrong, the higher the speeds (linear or angular) the more relevant the aero. What am i missing?
And, why data from Model 3 are so different from X and S? X and S numbers are not weird to me but damn, i can't conciliate with thoose of the Model 3 xD
It's not the actual diameter of the wheel, it's many factors associated with that diameter. A performance tire has more grip, therefore more rolling resistance. The SAME wheel in a larger diameter weighs more and is more rotational mass. If the larger wheel comes with a wider tire, more rolling resistance again.
In other words, the combination of the wheel and tire are the true factor, not just the diameter of the wheel. I can assure you that you can find some taller wheel combinations that will yield better fuel mileage if the wheel is lighter in weight, skinnier, and you mounted a Low Rolling Resistance style tire on it.
However, in *general*, the larger the wheel diameter, the more likely to have a performance tire (sticky) and the more weight and more rolling resistance.
It must be predominantly the total weight. If you look at the tables, the biggest effect is on the smallest (lightest) car at the slowest speeds.
My opinion/ guess is that the air flows around the inside of the rim differently at different speeds. Often at high speed, a bubble of air will form in a space, reducing aerodynamic drag.
There's another very clear benefit of smaller rims (= lighter rim): quicker acceleration!! This should not be underestimated, because we are talking about unspring weight. Excellent video by the way :-)
Don't own an electric car, but need to get new set of tires for my full size pickup. Thanks to this video, I now know what to do about wheel size and tire profile. Thanks!
"You can ask them: Why do you hate the environment?" :D
I can't hear you over how cool my 25" wheels look.
do they, though?
@@Turk380 he prolly has one of those jeeps that is garage queened
@@Turk380 He can't hear you over how cool he *thinks* his 25" wheels look.
@@TristanJCumpole this guy gets it
@@BirdiesGoCherp Obviously I am the only one....
We use to think: I would pay more and get bigger tires because they look cooler, now we think: I’m gonna get the bigger tires “to show people that I don’t have range engziety” lol
Anxiety*
@@kamikazi2500 yep- that. Lol
What I was hoping to learn from you was the difference in 1) mass of a large wheel with low profile tire vs. small wheel with high profile tire; and 2) the angular momentum difference in the two.
Total mass , wheel + tire
@@rp9674 That didn't explain anything.
I always watch these videos to the end. Most of it goes over my head but I'm comforted by the idea that if I really needed to figure something out, there's a formula for it. Great video. Save the planet with tires.😎
11:07 hahah bigger wheels on a tesla, make sure to ask why do you hate the environment lol
Tire shaming! Lol
So fat tires and small wheels? Sounds like a perfect drag setup to me...
You know it.
At what point does going smaller no longer improve range?
Practically, when the wheels no longer fit over the brakes and rotors.
When the friction of the car sliding on the ground equals the reduction in rolling resistance.
I didn't get why larger rims decrease efficiency. I mean the total diameter is the same (rim + tire), so what changes? Does the width of the tire/rim also increase with increased rim diameter?
How about wheel weight? When you go from alloy to steel Wheels?
And no mention of tire pressure?
His calculations account for optimal air pressure as stated from the manufacturer, but yes too much and too little has an impact.
i would assume they are using the recommended PSI
Guess my point is that tire pressure certainly impacts mileage and I was surprised he didn't stress that.
@@dwt51 Good point, because so often the average driver in a typical car (ICE or EV) has the tyres under pressure more often than not. It’s one of the best things about a good TPMS system, which nags the driver to top his tyres up. People are generally lazy when it comes to such things.
When it was time to get new tires, I went from 18" wheels to 16" rims. Lighter, when better acceleration and braking and softer ride. I make fun of the dealer when he tries to sell me on a car because of the size of the wheels. I say, " what are you, 16 years old?"
I thought it was more about the "Weight" and the (Rotational Mass)
Exactly, he didn’t mention the weight at all.
Weight of the wheel only affects energy required to accelerate the car. When driving at a constant speed, wheel weight doesn't matter.
@Art Uro That's because a fat, low-pressure tire has a lot of rolling resistance while a narrow high-pressure tire has very little rolling resistance. It doesn't have anything to do with mass. The mass of a wheel only affects the energy required when accelerating. And electric cars have regenerative braking, so even if the tire has more mass, then you get more energy back when decelerating.
Unsprung weight should make a difference and none of it is covered here.
As someone who works in the field, i would caution against a few conclusions. The 'C' term in the road load curve is not just aerodynamics, tire RR has some 2nd order effects. So you cant just compare aerodynamics in a vacuum when going from one wheel size to the next. Additionally, one somewhat decent metric for comparing wheel aerodynamic performance is the opening area. You could make a 20" wheel with a cover and it would be comparable to a 17", but generally thats a no-go from the styling department. That's why, in general it's harder to control aerodynamics on a larger wheel diameter but it certainly can be done and you'll find wheels that are good and bad regardless of size.
Sorry Charlie, Not entirely true- because you can’t control the aerodynamics of the BACK of the wheel- it DOES make a difference even though less than the front.
@@FutureSystem738 we are talking diameter here, not width. Width has a direct impact on frontal area and would be reducing your Cd if you could maintain the same drag hange point to change point.
@@charliewilson9062 I’m very well aware you’re talking about diameter. I should have used the words “inside” and “outside” of the wheel rather than front and back. There is still aero drag on the inside of the wheel, even though it’s significantly less than the outside where an aero cover can be installed. (It’s one reason some manufacturers like Tesla try to make the floor pan as flat as possible. There is still air moving under the car, and aero drag, and the inside of the wheels is all part of it.)
I have a Lexus Fsport IS350, I just bought 17's for my winter set (vs. the 18's on the summer/spring/fall set) the combination of taller sidewall, narrower section width (225 vs 255), and different tire compound completely change the handling characteristics, and as a result, my confidence in it's handling in the winter. I expect they will get better as the temperature drops, and I'll be experimenting with tire pressures, but I can't wait until spring comes when I can get my wider set back on.
Just something worth considering when having a wheel & tire discussion.
I wonder how the weight of the wheel factors in to all of this. Does the weight of the wheel make a difference at a constant velocity or does that only effect the amount of energy it takes to change the rate of speed of the wheel? So if you upgraded to a bigger wheel that is lighter than the smaller wheel, is that enough to off set the aerodynamic losses with all other factors equal? 🤔 Sounds like some experimenting is in order.
Great video👍
The weight of anything is almost a non-issue at constant speed.
Interesting video and nicely explained. One thing that would be interesting though is the difference of weights for larger wheels vs size.
For example would a 19" wheel that's 1kg lighter than an 18" have much affect on range? I know it's more acceleration but over the time of a full battery surely it's of some significance that could maybe allow going bigger and have less of an impact in range?
It's all about aerodynamics, it has almost nothing to do with weight. A slightly lighter/heavier wheel would change the inertia to overcome while accelerating, but do nothing steady-state.
Would've been interesting to also look at total wheel and tire package weight differences. Usually smaller wheels are significantly lighter, if I'm not mistaken.
The tyre would be significant more heavy assuming that the total circumference must be nearly the same.
Depending on material use for the wheel and which has more effect...extra weight of rubber against less weight of the metal.
Glad to see an analysis showing a positive environmental advantage of going for sensible over popular choices. Thx!
In general, you are correct with your results in the sense that for a given wheel dimension, a smaller rim is more efficient.
However, small tires in general are very inefficient. Because of this we see wheel sizes increasing. The tire with a small outer diameter has to spin faster for a given speed, because the radius is smaller, it gets more deformed --> less efficient. So a very large tire diameter is a thing increasing the efficiency! Just look at a BMW i3, a car that has been optimised for efficiency. There, the tire diameter is very large, the car has 21" rims as standard. Another benefit of that is, that you can make the tire even slimmer, reducing the area of the tire exposed to air resistance further.
So look out for an electric car that can fit a very large outer diameter wheel if you’re searching for maximum efficiency.
By the way: Those great looking rims with slim spokes are very inefficient, too. The standard M3 rims are very closed, creating less drag. They don’t look that cool, though...
checking BMW i3 base model specs from my local BMW web site: Tire = 155/70 R19 84Q, Rim = 5Jx19 LM so maybe those 21 inch rims you mention are some sort of option.
That was a VERY weird and unusual episode... 🤔
When looking at engineering explained, you typically can sit down and relax, being pretty sure that the perspective is going to be scientific. But here you are analysing the impacts of physical things, but when it comes to wheel diameter, you just basically say “Tesla says”! 😳
I’m not saying that Tesla is wrong, and I don’t hate high sidewalls, on the contrary - I love high sidewalls! (Yes, I am that old.) I like the tire to be/remain the mechanical vibration isolation that the tires were invented to be! And I like formula one cars to use wheels with high sidewall-tires!
So I’m really sad about the new F1-regulation change, applauded of coarse by the tire manufacturers that have been pushing the meme “big wheels/low tires is better/cooler/sportier” for so many years. 😕
But - you just can not just buy the numbers regarding range, directly from Tesla!
Other people play it like that, but not you! That is not scientific!
The range depends on so many things! Tire pressure for one. It just is so unscientific to talk about diameter of the rim so people with less knowledge mistakes it as something that’s proportional to the circumference of the wheel with a tire on.
So please be your normal self and go into the physics! Don’t just quote claims from Tesla!
If Tesla’s right regarding the range being almost inversely proportional to the rim diameter (even when to tires outer diameter is unchanged) then go into the WHY. Tell us about sidewall losses that becomes higher when the sidewall is exposed to a higher degree of relative deformation.
Or just ignore me. 😀 I am sometimes unnecessarily negative. ☺️
I'm pretty sure he used that data because a) it's available online b) it's very likely measured data c) it's pretty much impossible to calculate that stuff by yourself. You'd need to run very advanced CFD simulations on a very accurately 3D modeled car to get the drag data. Then you'd need to do some sort of physics simulations on how different tire sidewall heights affect range. It would probably take weeks of full-time work and very expensive software and hardware to be able to calculate this stuff. So why not use data that is already out there? I don't know about the USA, but at least in my country, false advertising is illegal. So if Tesla is advertising those range numbers on different wheel sizes, I'm pretty sure they aren't lying. And the most important piece of data there isn't the range itself, but the difference in range between different wheel sizes.
this is why I buy all my tires from Coker. bring back the bias-ply pizza cutters!
.
You just brought back memories of my 1962 Ford Falcon Futura.
Thank you for that.
The title should be: "Why Big Wheels Are A Bad Idea". It doesn't matter if the car is electric, ICE, or coal powered. XD
With higher tire walls, you also protect the rims a bit more from scratches. And the rims are less likley to break if you run into a big pothole.
I don't understand Jason leaving out so much information in this video. He talks about wheel diameter but fails to mention the wheel width for the different wheels. Often times the larger diameter wheels are for track performance and thus have wider wheels. Like the Taycan has rear wheels of 19" that are 265mm, 20" that are 285mm and 21" that are 305mm. Also the tire stickyness may change on what's fitted for the different rim sizes. Seems like a bit simplistic of an analysis to me.