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.

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

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

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.

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 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.

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

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.

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 :-)

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.

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

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

Make sidewalls great again!

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

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

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

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.

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

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

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

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.

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

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"

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

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

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

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.

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.

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

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

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

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.

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.

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

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

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.

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.

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

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.

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.

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

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.

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

Nice content! For bigger wheels + smaller tires, air resistance is an absolute god. Also, for low-profile tires on big rims, the tire has shorter and stiffer sidewalls. That has an impact during cornering and also changes the overall tire grip on the ground and rolling resistance. Howeever... For all of you going crazy over "I put bigger wheels+tires (both) & the computer says fuel economy is worse"... - 1st, your on-board computer is calibrated for specific stock size calculations. With bigger wheels+tires (both together) a 100-mile run looks like e.g. 95 miles for the computer. Its calculations are off. Recalibrate or calculate manually. - 2nd, always compare same-width, thread and type of tires. - 3rd, always compare with the same overall weight, fuel level, road strip & elevation, time, traffic, AC, weather, wind, outside temp, engine temp, etc. Best scenario: same type tires, tire pressure, compensate wheel weight difference, full tank, same gas station, same pump, circular or 2-way trip, at night, no traffic, no AC, dry road, no wind, warmed-up engine before fuel-up. - 4th, speed matters. Urban or motorway matters. Bigger overall size wheels+tires are better for higher speeds (easier to reach higher speed, less engine load). On the motorway, that's almost like a 6th gear in a 5-gear car. In urban areas, bigger wheels+tires hate lower speed (more engine load and fuel consumption). I haven't seen a single fully correct comparison online.

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.

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

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

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

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...

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

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

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)

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.

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

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!!!!

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!

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

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

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?

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

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

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'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.

Gordon Murray is 100% agreeing. He puts 19" wheels on the new T.50, and calls large wheels "nonsense" and "rubbish", "they are just styling and do nothing for you, they count against you on unsprung weight and ride quality", according to him.

Soooooo... Bigger isn’t always better?! You should tell that to my uncle! All jokes, your friends at Business Explained!!

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.

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.

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.

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

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

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.

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.

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?

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.

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?

What's crazy to me, is that as you go up through a model range into a more luxury specification, you get bigger wheels with lower profile tyres. Which makes the car LESS comfortable, noisier and more prone to punctures and rim damage.

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

At what point does going smaller no longer improve range?

One thing I didn’t see mentioned was the weight of the wheels as well contributing to the overall return as well.

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!

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. ☺️

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?

It's pretty wild that the Blazer RS with 21" rims and a ton of ground clearance still gets up to around 335 miles

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.

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

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

Wow! Thanks, for the enlightenment. Also, I see a far larger improvement at lower speeds for the model 3 --> 19.4% at 50mph and 21.96% at 40mph.

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.

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

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?

I'm lousy with math but I can give a real world testimonial. On my 2019 Model 3 Long Range Dual Motor, with the stock wheels and tires without aero caps I got about 300 miles on a full charge. With staggered 20" wheels and tires the range dropped to about 245 miles. What's even worse is the fact that acceleration was noticeably slower. Watching the WH/mile hover around 370 at 70mph was really demoralizing. I went back to stock wheels and tires after about 1000 miles.

I still don't understand why the smaller wheels have an increased range, I thought the low profile tyres had less deflection, therefore less rolling resistance. Can anyone explain this to me?

And no mention of tire pressure?

00:51 whiteboard! 🤣

I'm glad someone is finally pushing back against the completely arbitrary aesthetic preference for big wheels which, if I'm not mistaken, degrade performance in every area that would matter to a car enthusiast.

Anything that works against the ridiculous trend for larger wheels is, in my opinion, a good thing.