Why Big Wheels Are A Bad Idea On Electric Cars - Range Impact! 

I am absolutely delighted that Jason has built several videos from one pothole destroying his odd-sized Tesla wheel.

**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. 💪😂

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.

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.

I remember a race car engineer saying the ideal wheel size is the smallest you can fit around your brakes.

Board: *says 0.6* EE: "nearly ONE percent!"

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.

Me: **Looks in bank account**..........**Starts affixing grocery cart wheels to car**

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.

Hence the reason why the Prius always had tiny wheels - 15". Cheap stuff that was good stuff.

7:50 Changing tires at 75mph. You, sir, have one hell of a talented pit crew.

Make sidewalls great again!

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.

Sweet, so my 37" tires on 17" wheels for my truck is really saving the planet. Nice

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.

still doesnt really explain why larger diameter wheel leads to lower efficiency

For all cars, you just notice it more on electric.

"Lets say you have a very slim tyre, 205" - cries in 175

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 :-)

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.

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

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.

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.

As an ME, I absolutely LOVE your whiteboard work. Such a great channel. Cheers!

Well, Forza models this well since increasing rim size lowers the car's stats slightly

Remember when cars had 14" and 15" wheels? Pepperidge Farms remembers.

As someone that hates 20" wheels on anything, I am glad that math supports smaller wheel sizes.

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!

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"

On the upside, you don't have to worry about your wheels getting damaged by potholes since they're smaller sizes

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.

That's crazy the diameter of the wheel and not tire makes that much difference! You're the man Jason! Keep doing you!

Thank you for the great explanation :D Hope you are doing well in these weird times ;) Greetings from Norway

I would like to know the impact narrower tires have on braking distance.

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 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.

This is an extra reason. I want to get away from low profile because I drive on typical city roads a lot!

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.

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.

11:07 hahah bigger wheels on a tesla, make sure to ask why do you hate the environment lol

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.

Happy to finally see you cover this topic thanks Jason!

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.

6 inches of groudn clearance? *laughs in honda Fit

BMW I3 owners have just entered the conversation...did someone say pizza cutters? Lol

Tell me you're going to teach engineering? You're an outstanding teacher.

So you're saying the 35 inch tyres on 15 inch rims on my diesel truck are saving the planet. Phew! I was worried for a minute. Thanks, Jason.

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.

*BRING BACK 14" WHEELS...* and white walls too, why not?

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.

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.

"You can ask them: Why do you hate the environment?" :D

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?

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.

Glad to see an analysis showing a positive environmental advantage of going for sensible over popular choices. Thx!

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 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).

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.😎

People ask me about this EXACT thing all the time. Why do cars have big wheels now adays and what are the benefits? I tell them, each time, handling and steering response, everything else is a loss. Loss of HP, loss of gas mileage, worse comfortable ride, loss of money for higher cost of tires and the damage is more likely/often from potholes and curbs, more expensive wheels to replace, efficiency, etc etc. Of course, most people think larger wheels look better also... but that's just a trend that manufacturers have gotten into, which they could all back down on. As I tell them, it all comes down to balance. How much better handling and steering response do you want while sacrificing everything else. Each time, they state they'd prefer smaller wheels, as they don't even push their cars that hard. Now if all manufacturers could back down on the size, we'd be a happy planet. I don't prefer large wheels, stock size is good, smaller is even better. The limit being the size of the brakes and what can you fit over them. Usually, u can go down 1" or 2", sometimes 3", depending on the car. About 20years ago, cars had smaller than optimal, now we are waay larger than optimal, in my opinion. About 10-15years ago, wheels were the correct size, no need to go up or down. So go buy a used 10-15year old reliable car (Toyota, Mazda, Honda, Subaru), and call it a day. That's what I call efficient, and no electric car costing 4-10 times more can compete. Better yet, get an 10-15year old Hybrid/electric... but I can't stand those things, too slow, too boring.

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!!!!

If you lowered the tesla with 18in rims would you gain mileage?

Love the analysis! Thank you! In the rolling resistance analysis, I was thinking that the angular momentum of greater radius wheels would contribute as well..but as per your clarification below, since overall tire radius is the same, it's instead just taken into account in the graph curves that Tesla submits...?

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.

What about the unsprung weight added from bigger wheels, how does it affect performance and range ?

Would a 17 inch wheel increase range? Great video and as always, great information.

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.

Quite an amazing timing. Just changed my tyres from 185/65 14 to 245/40 17. Very helpful video.

So fat tires and small wheels? Sounds like a perfect drag setup to me...

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?

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.

Thank you for being the one person on youtube who understands car and tire physics!

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

I can't hear you over how cool my 25" wheels look.

Dude , I love you ! You are answering all my questions about my M3P coming soon . lol

I was the Guy at the Clarkston Service Center that was working on getting your wheels and tires ordered. I had quit before all the parts arrived, sorry. (4 1/2 years as Service in Michigan took its toll)

I have the best Tires. My wheels go around, like no other ones do. Many people say this about them. Great tires.

00:51 whiteboard! 🤣

the quality of these videos is amazing. Exactly what I was searching for (and the maths still works after 2 years, oddly)

It would have been interesting to know if this also effects cars with internal combustion engines to the same extent. I would like to suggest you doing a video on the placement of brake calipers and why they differ between front and back wheels and from one car model to another. Thanks.

At what point does going smaller no longer improve range?

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.

1:39 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

I didn't expect differences like this, that's just ridiculous! Bjørn should do a test!

I thought it was more about the "Weight" and the (Rotational Mass)

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?

Hey Jason! What 18” wheels did you go with that clear the performance brakes? I’m looking to drop down my wheel size also! Thank you and always love watching your videos! I’ve owned about 4 cars that you’ve owned and now I’m with you again on the Tesla!

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.

And no mention of tire pressure?

Wouldn’t the larger sidewall of the higher profile tire increase rolling resistance because it allows the tire to flex more?

I really liked this summary. It was well presented and easy to grasp. One thing I thought was missing is tire radius. There it is the other way round: larger radius gooder! (poor grammar intended) A prime example for this is the BMW i3 and the reason behind this, as far as I understand, is minimising the tire dampening losses as the tire gets deformed in the contact patch. Larger radius means less curvature means less deformation necessary to form a contact patch of given size.

Thank you. Very well explained. I do see about 10% loss in range with the 20’ wheels & tires. 🤦🏻‍♂️

When coparing the 18", 19", and 20" on a VW ID.3, Bjørn Nyland didn't really notice too much difference, may be like 3% total?

James Dyson: *laughs in 24 inch wheels* Maybe that's why his EV project failed!

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!

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.

this is why I buy all my tires from Coker. bring back the bias-ply pizza cutters!

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

Interesting vid! At first it was hard to believe adding 2" to the diameter would make much of a difference, but I got to thinking about my work with wind generators many years ago. Most of the power is made from the ends of the propeller. Power increases by the ^2 of diameter, and power is increased ^3 (cubed) of velocity. So, think of all this in reverse. The tips of the wheel spokes are traveling much faster with increased diameter. The wind load = speed ^3. Another interesting observation is that the wheels used on cars setting speed records on the salt flats have solid wheels.

I appreciate this video! I have a M3 Performance and I'm looking to get new wheels/tires. Definitely going to step down size to help improve efficiency but also for more a comfy ride. I plan as well to lower the car with TEIN coilovers. The wheels I'm looking at right now are Titan7 19" and the New Aero Wheels 19". I am wondering which one will get me better efficiency. Thoughts?