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<E36 M3>Tire Pressure

>>From: Mike Donahue <[email protected]>
Date: Sat, 20 Jul 1996 10:49:12 -0400

After my first autocross in my E36 M3 I discovered that it severely
understeered under all conditions, even braking.  I was using 44 psig on
all four to start.  Then I dropped the fronts to 40 psig and still
experienced the same.  Can anyone using MXX3 tires on this car relate if
they found a satisfactory tire pressure differential to minimize the
understeer?<<

1) Are these hot or cold pressures?

2) Well, this is what I used on my MXX3 and and use on my Yok A008P.  36 psi
front/34 rear (these are cold tire pressure).  The car is fairly neutral, at
least with my driving style.  My pressures after a 25 minute run session in
the advanced group (I'm not bragging, just that as my skills have progressed
I've found my tire pressures have gone up when I measure them after a
session) are near 44 psi all round.  About near the end of the run sessions
I've noticed the car tends to more easily oversteer than at the beginning.  

3) At risk of starting a flame war, are you driving a 95 or 96 M3?  BMW
(IMHO) went to 225 width in front and 245 in back vice 235's all round to
INDUCE understeer.  Understeer is "easier/safer" for a person not used to
throttle steering or oversteering.  By going to the new sizes BMW is just
trying to make the car a little less tail happy for the un-suspecting.  (I
managed to spin my M3 with in 2 hours of buying it when I nailed it on a off
ramp in the same manner I used to drive my 88 Celica All-Trac.  a) Celica was
AWD, b) Celica didn't have "instant" power, it was a turbo.  I immediately
signed up for a drivers school after that white knuckle ride).

4) Try and find someplace with a wet skidpad and experiment with the
transition from under to over steer.  A wet versus dry will save your tires.
 I'm not sure how tire pressures will translate from a skidpad test to a
track.  You tend to load your outer tires more in a skidpad, so I'd expect
the tires to heat up differently than on a track.

5) Carl Buckland in my opinion is one of the more seasoned E36 M3 autocross
drivers, but I think he is always on "track" tires vice street.  You may wan
to ask him.

6)I hope to have a set of the new Yok A032 next track session and I don't
have a clue as what tire pressure I'll be trying yet.  I'll post my findings.

YMMV

Marco