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Re: first auto X, what tire pressure? (read this o (archive)

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Posted by Randy Walters on September 30, 2000 at 16:46:02:

In Reply to: first auto X, what tire pressure? (read this one) posted by eric on September 30, 2000 at 14:27:08:

sorry I hit enter instead of tab on previous post. I'll be running revolution 16x8 with almost bald summoto HTR45Z's in the front and Venture plus. all rims are 225/45Zr's. what tire pressure should the be at, does them being almost bald change anything?
any other tips for the first timer?

It's hard to say without knowing anything about
your suspension setup, or what a "Venture" is.
Bald tires are better for autocross actually.
I'd start out in the 42-44 lb range up front
and maybe 40-42 lbs in the rear since you're
new. Drive smoothly so as not to over-drive
your tires (easy to do when you're learning)
and keep an eye on the sidewalls and make sure
they're not rolling over (you'll be able to see
the scuff marks where the sidewall meets the
tread). The trick with tire pressures is to
run them as low as you can get away with without
rolling over onto the sidewalls, then add a pound
for good measure. You may find that you need to
adjust your pressures in front or rear a few
pounds but that comes with more experience. Your
tire pressures will rise during your first run so
bleed them down a little when you get back in
line. Subsequent runs won't increase pressures
as much since the tire is up to temperature moreso
than before the first run. Tire pressure settings
is one of the more difficult things to determine,
especially when you're new. It may take several
events until you find what works for you and your
car, but my recommendations above will get you
in the ballpark.

Remember to drive smoothly and pay special
attention to the gas pedal (don't stab it, just
squeeze it on while feeling for the back to break
loose). Look ahead on course and do all your
braking in a straight line. Get back on the gas
gently so as not to upset the rear of the car.
Smoothness is extremely important in autocrossing,
whether it's steering, braking, or accelerating.
Turn-in gently so as not to "suprise" your front
tires (you don't want them to slide out when entering a corner).

Randy Walters
89 325is
So Cal DSP Champ

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