Is a wider tire on a narrow wheel faster?

FWIW, interesting article on The Drive regarding a Tire Rack test on if a wider tire on a narrow wheel is faster. The Tire Rack test is on video with a link to it in the article. You can see their conclusions and draw your own as well. The test used the new 200w Bridgestone RE71RS tires that have had positive reviews. I just picked up a set yesterday. https://www.thedrive.com/car-reviews/watch-the-answer-to-whether-a-wider-tire-on-a-narrow-wheel-is-actually-faster

Cool video and topic. I definitely agree that there is a correlation and a sweet spot between tire and rim width. Stock sizes are typically there to provide a sweet spot between traction and rolling resistance, which should result in target fuel economy, which OEMs need to take into account. Ride quality is also part of it as a tire is part of the suspension equation. So OEM sizes may not be the fastest but should provide the best blend. I think the big difference maker between tires (compound aside) is sidewall stiffness which should greatly impact how the tire feels and performs. It's quite interesting to see how far a tire will flex on the rim under hard cornering. It's all a balancing act and I'm glad they pointed out "what feels fast may be slow and what feels slower may be quick". I wonder if they ran the same exact pressures across all tests. Was a 245 tire on a 7" rim filled with the same pressure as 245 on a 9" rim? I can only imagine that this would play into how they perform. I know from road cycling, the correlation between tire, rim width and pressure has been a huge topic over the last few years that has flipped the traditional thinking on it's head. In the past, you'd run a 23c road tire on a relatively narrow rim with 17mm of internal width with a pressure of about a 100psi. This seemed to feel fast in theory but rolling resistance tests have shown it was not the case. Current trend is to run something like a 28c tire on a wider rim with internal width of 21mm at pressures as low as 70-80psi, depending on the rider's weight.

Just gives us one more thing to hotly debate on RL. i went with the 225 and 285 RE71RS oem size. Thought about going 235/295 but it didn't want to mess with my spacers. The bridgestones run a little bit wider. Curious about how they behave on the track. Tires have gotten better with each generation. Replacing a 6 year old set of toyo proxy R888 (V tread) which were 100w. Ok tire, but got greasy pretty quick. The RE71RS lap times are testing a bit faster than the new 100W Toyo R888Rs so I decided to give them a shot instead. One of these days I will get a bigger set of APEX rims. Just haven't decided on which ones yet. They all look good.

I was able to run 235/295 sizes on OEM wheels without spacers with zero issues, but I will say that tire shape is definitely a factor. Some tires will have a more rounded off sides (especially in the rear), like my old G Max RS, while the new PS4S I now have are a lot more squared off. I bet that there is a difference between the contact patch between the two, even though they are the same size.

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I am running 15mm spacers currently on the oem wheels. Have a set of 7mm spacers as well. Funny thing is you can't get the RE71RS tires thru the local Firestone dealer. Went there the other day to take a look and measure and they looked at me like I had 6 heads when I asked them about the tires. Tire Rack seems to be the key distributer. Once I have them on the wheels next week, I can see if there is more room for the 235/295 with 15mm spacers. If there is, I'll go bigger next round assuming they are good tires. Don't know how many heat cycles I will get out of them.

I have wondered about this for mostly academic reasons. It looks like The Wider Rim is fastest regardless of tire size in all but one case. Am I reading that right?

That's what I see as well. Go wider with rims and tires for more speed. But wider with tires on rims that don't proper support the tires leads to slower lap times. Kinda makes sense. Who wants sloppy tire play?

Interesting because bigger rim with the same Tire means heavier wheel/ rim unsprung and rotating Mass which should both be detrimental deficits.

I hear you. Add in aero and you may have a much slower car. Tricky.

I looked at it again, the guy says you want as narrow wheel as possible. He says that's what all the racers want. I think it sounds wrong. Maybe I am misunderstanding. https://www.thedrive.com/car-reviews...ctually-faster

Certainly there are alot more variables than were tested to maximize the speed you are able to carry on the track. Suspension set-up, tire pressures, sidewall strength, tire and wheel width. But it looks like the conclusion in the last paragraph is... "A well supported tire is better than a wider tire on a narrower rim." The RE71RS are very good sticky track tire. But you have to get the tire pressures right or you loose grip and speed. I found this year that they were sticky immediately and were awesome tires on the track. However, you gotta get the tire pressures up to 32/33 hot and they are good for an entire session without a drop off in speed. But, if you start with too high of pressure, you get immediate grip and control for the first two laps, then they get greasy because the adhesion patch becomes too small as the tire pressures build. Folks complain that they are not good mid thru the end of the session. What I found is they just started with too much tire pressure. Sidewalls are stiff (my preference) but the rubber is soft and sticky. I ran 225F and 285R on my 8/10 Carrera 5 spoke wheels. My set-up uses Bilstein PSS9s set to full stiff in the rear and half stiff in front, tarret sway bars set to full stuff in rear and least stiff in front. I have a guard lsd. This setup works beautifully with our standard 225F and 285R wheels mitigating understeer and allowing for crisp turn in but no issues with the back end coming around. Camber was set at -1.5 F, -2 R. Don't know what the characteristics and speed would be if I ran 235F and 295R on the 8F and 10R wheels, or even larger tire widths. Nor do i know if i would need to adjust my coilover or sway bar settings to make up for any changing characteristics. Same can be said for a 245F on the 8F wheel. Next year I'll test the 235F and 295R and see if there is any noticeable difference. My best guess is due to the sidewall thickness and if I get the tire pressures right, they may be slightly faster just because you have a little more rubber gripping the track. But wider rubber means more weight, and potentially less tire support so there is an eventual tradeoff at some point. not to mention the wider you go in the front in relation to the rear have got to dramatically alter the understeer/oversteer characteristics facilitating a need to make set-up adjustments to maximize handling and speed. The article and video do create a great discussion!

I tried 295s (PS2) on my stock 10” wheels. Looked good, but definitely didn’t feel as good as the 285s. Rear always felt “soft”. Ii wouldn’t recommend personally.

Okay, Basically each tire got faster with a wider rim. they were the fastest when they were Beyond spec. I'm not sure what to make of this. Apparently stretched tires go faster, work better. The rims never got so wide that the performance dropped off so would another half inch rim be even faster? At some point that doesn't make sense but I'm not sure they got to that point.

Nope. They didn't. Maybe we will see a Part Two from tire rack. But it's an expensive proposition testing so many tire and wheel configurations. Which is why we probably won't see Part Two. But the concepts make sense.

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Must be that the added grip is a larger benefit than the downside of the added rotational mass and weight.

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Makes sense especially on a shorter track like Blackhawk. At Road America it will be a drag on the straights. Extra HP/TQ will help. We walk a fine line with 300-320 HP.

Crazy thing is that 225 is faster than a 245 on all rims. What's up with that? I doubt many of us would mount 225 on a 9-in rim but that looks like money in this test. Can somebody please explain? It's possible that if it was a nine and a half inch or 10 inch rim the 245 might have been able to win, dry conditions anyway. Maybe it's a manifestation of the relatively low speeds because it looks like a small track, more or less autocross pace?

My guess is the sidewalls end up feeling tighter/stiffer and more responsive with a 225 versus 245 on a 9. Put it another way, you have more rubber with a 245 on a 9 versus a 225 on a 9 which may soften the ride and slow the inputs. Trade-offs everywhere.

My experience at lightning this past weekend. Not really scientific but similar track conditions for both. 200tw 245/35 315/30 with 6 days on 8.5" and 12" rims slightly faster than (4/10ths) 100tw 235/40 295/30 brand new on 8" and 10" rims

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How did the 295 on 10 inch feel? I know on my 964 I had a new set of wheels with bigger tires then I previously had but I liked them cosmetically and I would have sworn I could never be sensitive enough to feel the difference but I had to get rid of those after 2 days. Just too squishy. Went back to my 18-in rims with smaller side walls. I feel like I learned my lesson.

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I've had two sets of 295 on those 10" rims and had very good times with them. The previous set was a Conti contact force which is more of an endurance track tire. This set is toyo r888 and I'm not sure if I've got the pressures right yet. I usually start them out at 28f 29r cold and bring them down to 31f 33r hot. I will try both sets again next Tuesday at Lime Rock. When I drove it on the street the 225/40 285/30 seemed like a nice setup. On an 18" rim the sidewall height is only 1/8" different from the 285 to the 295. Also just check the max lateral g for both tires and the 315 was 1.84 and the 295 was 1.77.

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I think this is why they saw the drop off with the 245. Remember, they were driving a stock BRZ with 2/3 your HP. Guys at my local track run highly modded Miatas (likely in neighbourhood of 250+ HP) on 245 and claim the jump from 225 to 245 is life changing...but on 9� wheels.

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That's good data. How do your lap times compare? Makes me wonder what they would both do on comparable 11-in rims.

Hello, I'm a little late to the party on this thread, but I have some input from track experience with the Bridgestone RE71. I was recently at NCM (Bowling Green, KY) with my 2023 Civic Type R running appropriately sized Bridgestone RE71RS's. They were properly inflated and heat cycled. Both of the front tires failed after about 15 laps. I heard some sudden odd noise and vibration and came off the track. Both of the front tires had enormous bulges on the inside. I was driving aggressively (2:20.7 was my best lap) but everyone who saw the tires or photos of the tires said "I've never seen that before". I'm assuming Bridgestone was unconcerned as my tire shop whom I've done a lot of business with kind of ignored the situation - I guess failures on track are always attributed to driver abuse/error. I really should have bought the tires from Tire Rack as they likely would have at least wanted to know the details of my situation and may have a more direct relationship with Bridgestone. I was never looking for any remuneration. I was and am far more concerned with how potentially dangerous these tires could be when used on track. Another lap or two and they could have ruptured at speed.

It's a rabbit hole trying to get to the root cause of such a failure because it's almost impossible to find out what was done to and with the tyre. How was it mounted, what pressure was required to pop the bead over the humps and make it seat properly, what pressures were run when cold, what wheel camber, what speeds, what loads, how were curbs taken, how high and steep were those curbs etc etc. Otoh a carcass failure as seen here leads to bulges and vibration I.e. it announces itself and anybody with some sense and running on a track will pit and check. As such it's not a disastrous sudden failure. Also Bridgestone will have done the testing they deem necessary prior to sign-off by Honda (if they supply Honda for the civic type r) and fulfill al legal requirements for a public road tyre. And then they have all sorts of monitoring in place during manufacturing of the tyre and of course they monitor the market through their sales. As such It requires more than one damaged car set of tyres before they dive into analyzing the damaged tyres and feel something during manufacturing has gone wrong, missed it and those tyres inadvertently reached the final customer. It might not be what you'd expected but it is neither surprising nor worrying that the shop or Bridgestone are not alarmed.

Saw a toyo 888, 305 on a 12" rim do the same thing. Sometimes the belts just break. Track driving is very hard in tires and they do fail from time to time. I had a side wall fail on a hossier at watkins. I inspect the insides if my tires regularly.

I ran the RE71RS a couple of track days this season. I like them, but don't know what their limits are as of yet for varying tire pressure ranges, as well as heat cycles of which my guess is between 10-12. But only a guess until I run thru a few sets. I wouldn't cord them. But I wouldn't willingly cord any tire on the track. They were also a bitch getting them on the wheels. I bought them thru tire rack and had the mobil installer come out to the house to install them. But they were unable to get them sealed on my Carrera 5 spoke wheels. Very stiff sidewalls. So they then took them to the local Discount tire to do it. No luck. I told them to forget it and I would take them to my indy which is who always does my new tires, except this one time. So my indy said no problem and wrapped a strap around the circumference of the tire and spread them and got them sealed. No heat and no flames. Just a strap and a high pressure hose. Point is that the procedure used to get them sealed on the rim may or may not be a contributing factor. Dunno yet because they are too new with very little available info. However, so far I like the RE71RS. But it's still too new of a tire as of yet to understand the quirks. Glad you posted what happened. Sorry it happened.

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If you are talking about me it was a 295 on a 10� rim. Only 5 heat cycles.

This is not the first occasion I have seen of the 295/30 R888R blowing out the inner sidewall. https://rennlist.com/forums/racing-a...during-de.html

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This was the Toyos? How did the sidewalls feel before the failure? I ran the Proxy "V" treads for a couple of years and didnt like them. But didnt have much of a choice with size availability back in 2015-17. Sticky rubber but squishy sidewalls and i couldnt feel the track nomatter what pressures i ran. But had to start at about 24lbs to get to 32 when hot to get the best grip.anything above that pressure facilitated a greasy feel half way thru the session. But was never confident the sidewalls were strong enough. Curious if the new proxies are any stiffer than the old and more responsive to feel. Probably going to try a set of AR1s next season as well to compare to the RE71RS.

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Meh it was a guess....u do have some 305s and a 12" rim so i was maybe 10% correct.

Multiple guys have had failures with R888R on 6TT's as well. These rear engine cars put a lot of stress on the rear tires.

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Yipes. I don't think anyone would accuse you of stretching that tire so that must not be the cause. As far as stretching goes it looks like it gives faster times for a given Tire size. At what point does that benefit drop off or is it only when the Tire is no longer Seated on the bead?

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I can answer this. Obviously different tires behave differently, but almost all 200tw tires prefer being mounted on or near their maximum rated wheel width. Some are super obvious like A052's, where a 265 on a 10.5 is the fastest that 265 will get. More tire will go marginally faster given the same wheel width, but at some point the sidewall rollover will force you to use more tire pressure than the tire wants and that's where you stop. For example I don't think anyone competitively uses 295 A052's on a 10J wheel, it's around 275 tops and even that's pushing it. I have 265 on a 9.5J for my BMW and it's very gummy, when I'm able to fit 10's the 265 is much more precise and predictable and that produces better lap times.