From digest.v7.n1340 Wed Mar 18 19:59:01 1998
From: Duane Collie <trapdnce_at_erols.com>
Date: Wed, 18 Mar 1998 18:40:16 -0500
Subject: Wheel jobs

>     I have heard that I cannot go with different sizes on the '95 like the

>     newer '97 and '98 models. Apparently the '95 is setup for the same
>     size tires all around (wider tires on back cause significant
>     understeer?).

><snip>
>
>Currently running 8.5" LTW forged wheels at the rear with 245/40 MXX3's and
>7.5" (also LTW forged) in front w/stock 235/40 MXX3's. No noticeable
>understeer.

Hey guys - Don't ferget your offsets! Too much offset and you'll be cutting wheel arches and welding on flares.

Here's the various 17" combos that DO work on a '95 M3 - all assume a non-lowered car:

7.5" x 17" 41 mm - this is stock and you should use it if you want to run SCCA A-Stock Auto-X.
8.0" x 17" 35 mm - this is the max offset with a 235/45 series BFG R1 without rolling fenders.
8.5" x 17" 38 mm - that's all folks, any more and you'll be rolling the lips of the fenders.

Not to worry if you stuff a little bit too much wheel and tire in there. You can alter the fronts to clear the spring perches by adding a simple wheel spacer and you can also roll the rear fenders (not a big deal, but sounds scary).

The numbers above can be varied a little bit, for example, you can take the 8.0" x 17" and get a 44 mm offset and have absolutely no worries on clearance but you lose some of that sweet deep dish look. So you can generally go HIGHER numberically on the offsets, but not lower.

When you lower the car and play with camber tweaks all the angles change and then it's guessing time. Also, the BRAND of tire can vary in the width and differ slightly.

I'm very much in favor or running same size wheels front and rear so you can rotate the tires and not be burning off two sets of rears for every front set. I'm currently running 8.5" x 17" all the way around 37.7 mm offset with 245/40/17 Bridgestones and a set of 8.0" x 17" BBS RC's with 38 mm offset and 235/40/17 Yoko A032R's for the track. The street tires and wheels BARELY fit, and the rear lips are rolled, but then my car is lowered.

You might be able to squeeze in a 9" width rear rim in the back if you do the math, read the specs and get something with a high offset. A few of the guys have done it I understand, but unless you're Jim Conforti and going for 500 hp +, it may be overkill for the street.

Better also to fix the understeer in the car with adjustable sway bars - not tire sizes.

Duane Collie
RM3DR1 / UUC
National Capital Chapter

P.S. Same thing applies to non-M3 E36 cars, but ya'll have to install a steering limiter when you step up to 17" wheels. Again, no big deal.