Hi Mike -
Since Kevin called my name in his post, here goes...
At 01:56 PM 4/26/2001 -0700, Mike Eynon wrote:
>The way I see it, I have 3 options --
>
>1. Get the same size tires that I am running now. These are sure to fit
>without damaging the car, but they come with the same problems that I have
>now... mainly that I cannot rotate them.
Rotation will be a problem anyway, because the 96+ M3 only came with the
7.5" front/8.5" rear rims. I don't know if there was an option to get the
7.5" rims all the way around, like on the 1995 M3. Since you're in a stock
class, you'll need to do some research and find out if there was a factory
option to get the 7.5" rims all the way around. If there was, then you
have a choice - you can get a set of 4 17x7.5" rims, and rotate to your
heart's content, or get a set of staggered rims where you'd have to get the
tires remounted every time you want to rotate front-to-back.
If there was no factory option, then you have no choice - you're stuck with
the 7.5/8.5 setup.
>2. Get 245s all around. This sounds great, but I am not sure that
>they will
>fit. Besides the extra width, the Kumhos are about .6 inches greater in
>diameter... and I don't have all that much room under the front wheel well.
>I would definitely need to talk to someone who has direct experience with
>this before doing it. The last thing I wanna do is have to send 2 wheels
>back, or have to sell them myself.
The problem places for tire clearance on M3s are between the tire and the
strut in the front, and between the tire and the inside of the fender or
the tire and the muffler in the rear. There's usually plenty of room for
the top of the tire to fit in the wheel well, unless you've done a Navid
and slammed your car. :-)
I ran a set of the 245/45-17 Kumhos on my car, but unfortunately I don't
remember if they were on stock rims, or on 17x9" rims. They needed a small
spacer in the front to clear the strut. My rear fenders have been rolled,
so there was plenty of clearance in the back without changing the
offset. However, the extra height does noticeably affect your
acceleration. So, after seeing them fit on Navid's car, I went to the
255/40-17 Kumhos...but Navid and I don't have stock suspensions, and have
done a little goofing around to make them fit. So, until you can find a
set to test-fit, I wouldn't really recommend the 255/40s.
>3. Run 225s all around. This sounded funny to me until my friend pointed
>out that the tread width on the 225 Kumho is nearly a half inch wider than
>the tread width on my 245 Potenza S02 PP street tire (according to the
>TireRack tables).
I'd vote for this choice! Trying to squeeze in another few centimeters of
rubber won't really make that much difference in your times at this
point. Also, the slightly skinnier tire will give you more clearance so
you can get a more aggressive alignment, which will help eliminate the
understeer in the car.
Speaking of alignments, it's one of the cheapest things you can do to make
your car a better autoxer. I'd recommend going to zero toe in the front,
and using the BMW camber bolts in the front to get as much camber as you
can. Unfortunately, there's a tradeoff - if you do this, the car may get a
little twitchy at speed, be a little more susceptible to tramlining, and
the extra camber will make the inside edges of your tires wear more during
every day driving. However, the alignment changes will reduce the amount
that you're scrubbing the outside edges of your tires, and make your car a
little more nimble. If you can practice unwinding the wheel like Kevin
says, and braking early for turns and not dive bombing them, your tire wear
should improve, too...
Hope this helps,
Jim
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