OEM tire size for M3 question

[ClubSport332ti]

Can I run 235/40/17 up front instead of the 225/45/17? i think i like the low profile look of the 235/40 better

[nismo skyline]

yea u can without any problems

[ClubSport332ti]

so 235/40/17 on a 7.5 inch rim like the 95 in the front and 245/40/17 in the rear. This sounds like the perfect set up IMHO, I wonder why more people dont run this

[Daved]

235mm is "a little" too wide for a 7.5" rim IMO. Most people will say it's fine but if you want to do the right thing, check the specs of the tires before getting them and see what's the recommend wheel size for them.

[ClubSport332ti]

235mm is "a little" too wide for a 7.5" rim IMO. Most people will say it's fine but if you want to do the right thing, check the specs of the tires before getting them and see what's the recommend wheel size for them.

Well in 1995 the wheels are all 7.5 and they run 235/40/17. In 1996 they staggered them and the front went to 225/45/17 on a 7.5 inch rim and 245/40/17 on a 8.5 inch rim

[Nunzio]

I'm running 235/40/17 in 8" rims all the way around , I thought it looked too small at first but it's a great setup.

[ayton]

you can do it no problem.

[Chris Huff]

so 235/40/17 on a 7.5 inch rim like the 95 in the front and 245/40/17 in the rear. This sounds like the perfect set up IMHO, I wonder why more people dont run this

I would try to run the same size all the way around. It will understeer less and make the car handle a little better for you.

[KTL]

Actual tire size varies quite a bit from manufacturer to manufacturer. So it is possible that a 225/45 could potentially perform equally or better than a 235/40. Reason I say this is because if you went with a "narrow" 225/45 tire on the 7.5 in. rim, the tire could be more stretched across the rim width than if you chose a "wide" 235/40 tire for the same rim. A wider tire is not always better (although the shorter sidewall does indeed improve stiffness/stability) in some cases. You want to maximize rim width for a given tire size, not necessarily the other way around. As in, "what's the widest tire I can fit on this rim?" A tire that is nicely stretched across the wheel is said to be better performing than a wide tire on a seemingly narrow wheel, where the tire looks pudgy @ the sidewall. The stretched narrow tire supposedly has a better-shaped contact patch than the flabby wide tire.

All of the above is assuming extreme conditions. Since were talking about a 225 vs. 235 tire, the differences may be negligible at best. It's also possible that simply choosing a different brand of tire could make a huge difference in oversteer, understeer. And i'm sure the guys @ BMW knew what they were doing in sizing wheels & tires. But, at the same time, we have to remember that the BMW guys try to reach a good middle ground/compromise in comfort & handling. So they may not have necessarily provided the best wheel & tire setup for optimum performance. In the end, wider is better. But which wider? Wider wheel yes, but not always wider tire.

[ClubSport332ti]

I would try to run the same size all the way around. It will understeer less and make the car handle a little better for you.

I have staggered wheels so that might be a little hard

[Chris Huff]

You can run 235/40-17 on 7.5 & 8.5 wheels.

[98estroilm3]

Well in 1995 the wheels are all 7.5 and they run 235/40/17. In 1996 they staggered them and the front went to 225/45/17 on a 7.5 inch rim and 245/40/17 on a 8.5 inch rim

You are incorrect, 96+ wheels use a 225/40/17 not 45 profile. You should never mix/match different profiles i.e. 40 fronts 40 rears.

OEM tire sizes for 96 staggered call for 225/40/17 front 245/40/17 rear. You can run a 235/40/17 in the front 7.5's and up to a 255/40/17 safely on the rear 8.5's.

[hal9000]

You are incorrect, 96+ wheels use a 225/40/17 not 45 profile. You should never mix/match different profiles i.e. 40 fronts 40 rears.

OEM tire sizes for 96 staggered call for 225/40/17 front 245/40/17 rear. You can run a 235/40/17 in the front 7.5's and up to a 255/40/17 safely on the rear 8.5's.

Actually, he's right, OE spec on a e36 M3 96+ is 225/45/17 front on 17x7.5" rims 245/40/17 rear on 17x8.5" rims. .

[KTL]

You should never mix/match different profiles i.e. 40 fronts 40 rears.

On what basis is this statement made?????

My 87 Porsche came from the factory with 205/55-16 front on 16x6 wheels and 225/50-16 rear on 16x7 rear. Alot of people run 205/55 w/16x7 and 245/45 w/16x8,9

I also have a set of 17's where I run 225/45 fronts and 255/40 rears!

The reason for the different aspect ratios (you call them profiles) of the tires is to generally maintain the same overall diameter of the tire, when the widths are different.

[ClubSport332ti]

I ran 235/40/17 on all 4 but the rear looked really unprotected. The side of the rim stuck way out. It did look great though, especially on my car

[s_ribs]

You are incorrect, 96+ wheels use a 225/40/17 not 45 profile. You should never mix/match different profiles i.e. 40 fronts 40 rears.

OEM tire sizes for 96 staggered call for 225/40/17 front 245/40/17 rear. You can run a 235/40/17 in the front 7.5's and up to a 255/40/17 safely on the rear 8.5's.

No, you are wrong. Like I said in another post (I believe to you) profiles are only the same front and rear if the width is the same. 225/45-17 is the proper fron size for the staggered set-up.
Seth

[s_ribs]

235mm is "a little" too wide for a 7.5" rim IMO. Most people will say it's fine but if you want to do the right thing, check the specs of the tires before getting them and see what's the recommend wheel size for them.

Exactly. Check the specs before you do it. When I bought my car I put new Yokohama AVS Sports on immediately. Since my '95 had the light-weight M3 wheels I decided to go 235/40-17 front and then 245/40-17 rear. The 235/40 Yokohama's were simply too wide for a 7.5" rim. I checked the specs and they said a 8" rim was the minimum for that size. My tires definitely look too wide for the rim. You can see that the tire sticks out quite a bit from the rim. Probably not very good from a handling/responsiveness standpoint.

I just bought new tires which I should get tomorrow, Khumo Ecsta MX, and I went back to 225/45-17 for the front. I will let you know any differences in responsiveness with a better matched tire width to the front rim width.

Definitely check the specs first. I know it was the stock '95 M3 set-up, but not all tires are created equal.
Seth

[Chris Huff]

I have a 1995 M3 with 7.5" wide STOCK wheels. It also came STOCK with 235/40/17 tires. That is how BMW decided to size the tire/wheel combo.

I know that some specs say you shouldn't go less than 8" for a 235/40, but this is how BMW did it.

[s_ribs]

I have a 1995 M3 with 7.5" wide STOCK wheels. It also came STOCK with 235/40/17 tires. That is how BMW decided to size the tire/wheel combo.

I know that some specs say you shouldn't go less than 8" for a 235/40, but this is how BMW did it.

You are correct! Like I said, each tire is different. Some are narrower and will fit just fine, some are wider so they will bow out (like I experienced with my 235/40 front Yokohama tires as mentioned above).
Seth