235/40-17 on 7.5 rim?

I would like to get some feedback on running Star Spec (or similar) 235/40-17 on 7.5 rims. I know this was the stock size for 1995 E36 M3's and I still see a lot of cars running this configuration, but are there any negatives in comparison with a 225/45-17 on the same size rim? It seems like the common trend is to run narrower tires stretched on wider rims whereas the 235 would be slightly pinched on a 7.5 although still slightly wider than a 225.

Thanks in advance, John

I'd do it. Then again my opinions on tire fitments seem to run against the grain.

I have235/60's on my 7" rims and they fit fine, but it is not a performance application. With the extra 1/2" you've got, should be fine.

Depends on the tire.......Dunlop, Hankook, and others have basically said "berkeley this system of measuring, we'll just make it seem close".......so their tires run WIDE. I had 235/40r17 star specs on my redline, and the factory 7.5" wheel wasn't wide enough. It felt squirmish nearing the limits, low and behold, I found out it was rolling the sidewall under the wheel heavily. I went to 8" wide wheels with the same tires, and it behaved much better. I have 245/45r17's on a set of 17x8's on my '91 sho now.....and they're honestly nearly too wide for the 8" wide wheel.

What tire specifically are you wanting to run? 215/45/17 has some bargains in it. 225/45/17 has super sticky stuff. Pay attention to section and tread widths, and you can actually find some 215's to be larger than 225's and on par with 235's, as well as the inverse.

With a 40 or 45 series tire I wouldn't worry about it. I've got 195/60-14 General HPs on my Prizm on the stock 5.5" alloys. Edge of the recommended rim with. Barely looks pinched. Doesn't handle any different(like a big FWD go kart) than it did on the stock size185/65-14 tires it came with.

If you can get both tire sizes for the same price i would pick the 225. The un-quantifiable loss of 'communication' you get with the wider tire is not worth the slight amount of grip that you may or may not gain.

Thanks for the feedback. I'm slightly surprised that a lot of the early E36 cars still run the 235/40-17 and 7.5 combination if the steering feel is so detrimentally impacted.

BMW switched from the 235 square setup on the early MP3 to the 225/245 setup to induce a little basic understeer. I have switched to a 235 square setup on the street on the 7.5 wheels and love the handling and it is really nice to be able to rotate the tires. I did one track day with this setup and really enjoyed the rotation at corner entry and was still able to apply power early with the car not over rotating with power.

Mostly I track with a 245 square setup on 8.5 wheels and this gives the same balance but higher grip levels. This setup on the street could get me in trouble;)

Depends on the tire.

I just got a screamin' deal on a set of Toyo 888s in 235/40-17 for the M3. I put them on 8.5" Kosei K1s and they're not stretched. I drove them very hard at Summit Point/Shenandoah and was really impressed w/ turn in, balance, and absolute grip.

I've had RE01Rs and Star Specs in 245 as well as RA1s in 235 on these rims in the past, as well as 255 RA1s and Hoosier R6s on a set of 9" wheels.

If it's a really wide 235 on a 7.5" you may lose a little "crispness" at turn-in. For street though it'd be comfy and nice.

I have 225/40-17's on a 7.5 rim on my 330. Unless it's a really wide 235, I can't see it being an issue.

motomoron wrote: If it's a really wide 235 on a 7.5" you may lose a little "crispness" at turn-in. For street though it'd be comfy and nice.

This!!! In the autocross world it's not uncommon to see 255s on the 7.5in wheels. The steering will feel a little dull, but not enough to kill the deal.

Spoolpigeon wrote:

motomoron wrote: If it's a really wide 235 on a 7.5" you may lose a little "crispness" at turn-in. For street though it'd be comfy and nice.

This!!! In the autocross world it's not uncommon to see 255s on the 7.5in wheels. The steering will feel a little dull, but not enough to kill the deal.

The top guys in B-stock CRs run 275 hoosiers on 7". And some people look at me funny for my 225 Rivals pinched onto 6.5" (AP1 front).

I've got 235/45-17's on my 17x7 Infiniti rims, no problems here.

In reply to Josh:

I haven't seen 275s on them yet, but I'm not surprised about it either lol.

The stiffer the tire sidewall, the more accepting it will be of being pinched on a rim before the tire starts shifting around under the rim like crazy. 235 on a 7.5 is really only borderline objectionable. Many aggressive tires would take well to it. Some tires probably wouldnt, either the very wide 235s or tires with softer sidewalls.

yamaha wrote: Depends on the tire.......Dunlop, Hankook, and others have basically said "berkeley this system of measuring, we'll just make it seem close".......so their tires run WIDE.

Troof.

My 195-55-15 Star Spec Z1's are loser to a 205. They are a wide-ass 195.

all this being said; how about a 245/40-17 (dunlop star-spec in this case?) on a 8" wide wheel?

I run that size matchup on my dodge dynasty (yep) and the tire is about 'square' to the rim. I figure a star spec runs on the wide side of 245 so i'd figure on slightly pinched but not too bad at all.