Matching Tire Width to Wheel Width

I was reading an old GRM tire test article on performance tires a while back. They said best results for track were obtained when the tread width matched the rim width. I don't remember much else.

So for an 18 X 9.5" rim, this would put you at a 245 tire. But most track rats I know would run something like a 265 or a 275 on a 9.5-inch.

What do you guys and gals think?

I think that article was speaking to how to get the most performance out of a tire, not necessarily the other way around.

The 245 would be fastest on a 9.5-10" wheel. That's not necessarily the fastest a 9.5-10" wheel can go.

It was just one test with 205/50 and 225/45 Rivals on 15x8" and 15x9" wheels on a TSX powered CRX. The two tires ran nearly identical track times on the 8" wide wheels, but the 225s on 9's were somewhat faster.

I have 225/50 V710s on 16x9.5s now, and they work pretty well. They feel great. I had 225/50 V710s on 15x7s for awhile which felt sloppy.

It is hard to say what size tire will be marginally faster or slower, but it is pretty clear to me what feels better--lots of rim width and stretch.

FWIW: 9.5" wide wheels are still in the suggested range for 235/40 tires.

Jamey_from_Legal wrote: I was reading an old GRM tire test article on performance tires a while back. They said best results for track were obtained when the tread width matched the rim width. I don't remember much else. So for an 18 X 9.5" rim, this would put you at a 245 tire. But most track rats I know would run something like a 265 or a 275 on a 9.5-inch. What do you guys and gals think?

There is a difference between tread width and section width. They are usually related, however.

This is interesting.

If you take a popular track tire like the Nitto NT-01 (at least, it's popular with heavy cars like the E46 and E92 M3), commonly run on 18-inch wheels, here's how Nitto specs them (tire size, overall width, rim range (measured)):

225/40ZR18 9.06 7.5-(8.0)-9.0
235/40ZR18 9.49 8.0-(8.5)-9.5
245/40ZR18 9.72 8.0-(8.5)-9.5
275/35ZR18 10.91 9.0-(9.5)-11.0
275/40ZR18 10.94 9.0-(9.5)-11.0
305/35ZR18 12.32 10.0-(11.0)-12.0
315/30ZR18 12.60 10.5-(11.0)-11.5

They seem biased towards over-wide tires for a given rim.

I think I'm going to give 245s a try next time I need tires, and see how it works out.

Jamey_from_Legal wrote: This is interesting. If you take a popular track tire like the Nitto NT-01 (at least, it's popular with heavy cars like the E46 and E92 M3), commonly run on 18-inch wheels, here's how Nitto specs them (tire size, overall width, rim range (measured)): 225/40ZR18 9.06 7.5-(8.0)-9.0 235/40ZR18 9.49 8.0-(8.5)-9.5 245/40ZR18 9.72 8.0-(8.5)-9.5 275/35ZR18 10.91 9.0-(9.5)-11.0 275/40ZR18 10.94 9.0-(9.5)-11.0 305/35ZR18 12.32 10.0-(11.0)-12.0 315/30ZR18 12.60 10.5-(11.0)-11.5 They seem biased towards over-wide tires for a given rim. I think I'm going to give 245s a try next time I need tires, and see how it works out.

That's a range. Will depend on car, driver, lawyers, etc.

I'm about to be testing this theory, sort of. I've run 255/50-17s (8" measured rim width) on my factory 17x8s for a few years. They performed admirably both on the street and for autocross, never feeling squirmy despite the relative tall sidewall.

I'm about to swap to 18x9s I picked up new and dirt cheap, and I'll be running 275/40-18s with a measured rim width of 9.5" I'm hoping that the slightly shorter sidewall will offset any squirmyness from the rim being the narrowest allowable spec (1/2" under measured rim width.) Some of the 255 -18s have a measured width of 9, but they are way off on total wheel diameter - enough so that I wouldn't be happy running them. I prefer to stay close oto the factory tire height for many reasons.

Tread width matching rim width is pretty much how i like to run...it gives the best balance between agility and grip from my experience. Right now I'm running 205/45-17 street tires on 17x7.5" wheels with a +40mm offset for my FR-S. Stock tire size is 215/45-17 on 17x7" wheels with a +48mm offset. The 205/45-17 tires on 7.5" width rim give better steering precision, has a slightly bigger tread width than stock, and actually has a better ride quality over stock as well...(a ~4lbm reduction in unsprung weight over stock is what really helped with that I'm sure...) Also with the reduced diameter (0.3" smaller), there is a lower CG (~.15") and quicker acceleration/deceleration.

I wish I had the time and money to run a decent test of the premise.

But wait, what if a magazine, with access to tire manufacturer test loaners, were to do it? Wouldn't that be cool!

I have a bud who runs 285's on a 9.5" wheel, sits pretty square. I run 265's on my 9" wheels.

I run 275's on a 15x10" wheel

This subject is relevent, 245/50/16 nt-01s on a 8 inch. They feel a little spongy on the street and I believe would act better on a 9.5+. We will see how the first autocross is, but they comfortable on the road :)