[s-cars] Which pressure do you use in your tires for a track day

[Trevor Frank]

I would start with 2-3 pounds lower that what you run on the street.  If
it is raining maybe 5lb's lower to help get some heat into the tire.
Look for the tire rolling over onto the side wall.  This could mean that
you are to low, that you have a sidewall that isn't stiff enough, that
you don't have enough camber, that the suspention is to compliant.

With 17's and a HRZ2's running 2.5deg camber in the front, I couldn't
get the tires not to roll onto the side walls, and I was coming off of
the track at 50+psi.  There was a Toyo rep and he was at a loss, we
talked and we suspected that the tires couldn't handle the car, they not
only where not stiff enough they also lost big chunks out of the tread.
I went back to the drawing board and hit all possible problems, I went
to an 18 that is a known good track tire, S03, I stiffened up the front
suspension and raised the front suspension as well as stiffening it up
with higher rate springs and putting in a spherical bearing on the top.


With an 18" 35 SO3 I run around 35psi front and rear,  coming off of the
track in the mid 40's.  With the tire rolling over just right.  With the
spherical bearings in the front to maintain my camber setting so I can
get away with it set at 1.5 in the front and 1.3 in the rear.

I suspect that there is more traction to be gained with more camber but
I really don't want to have to change my setting around every time I go
to the track.

With modern tires reading the pyrometer when you come off of the track
gives little insight to what is going on.  I have talked to several tire
guy's about this.  The temperature loss and conductivity the current
radial tires is such that the data is often misleading.  I have had them
recommend that I set the camber, and adjust tire pressure to get the
appropriate amount of roll over.  I have been looking and some day I
would like to build an IR tire reader with 3 -4 IR sensors so that I
could monitor tire temps on the track.

-----Original Message-----
From: Frederic L'Huillier [mailto:flhuilli at hotmail.com]
Sent: Tuesday, November 11, 2003 2:25 AM
To: s-car-list at audifans.com
Subject: [s-cars] Which pressure do you use in your tires for a track
day

Hi,

I am wondering at which pressure do you set your tires for a track day.
I suppose  (but may be I am wrong) you don't use same pressure for a
summer
track day versus a winter track day.
Anyway thanks for you advices.

Cheers,
Frederic

_________________________________________________________________
MSN Search, le moteur de recherche qui pense comme vous !
http://search.msn.fr/worldwide.asp

_______________________________________________
S-CAR-List mailing list
S-CAR-List at audifans.com
http://www.audifans.com/mailman/listinfo/s-car-list

=======
Notice: This e-mail message, together with any attachments, contains
information of Symyx Technologies, Inc. that may be confidential,
proprietary, copyrighted, privileged and/or protected work product,
and is meant solely for the intended recipient. If you are not the
intended recipient, and have received this message in error, please
contact the sender immediately, permanently delete the original and
any copies of this email and any attachments thereto.