S-02 psi for autocross?
02-27-2003, 04:51 PM
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Could anyone with autocross experience please give me some insight as to what tire pressure they like to run in S-02s running on asphalt? I usually ran 37psi cold up front and 36psi cold in the rear. However, at my last autocross, someone recommended running a few psi less so I dropped 2psi front and rear. It seemed to improve my grip (and times). So I'm wondering, how low do you guys run at? FYI, my tires have about half their normal tread left.
Thanks.
-Pete
Thanks.
-Pete
02-27-2003, 08:09 PM
#2
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varies. on the road course I say stick em with 36#'s cold all around and tune from there.
with autox its a bit different. you can always use shoe polish or some other markings to figure out just how much your tires are rolling over and where you might need to increase or decrease. one tip from Saini was to set the fronts up for steering and the rear for tuning oversteer/understeer.
try to take a few recommendations and determine what best suits your driving abilities.
with autox its a bit different. you can always use shoe polish or some other markings to figure out just how much your tires are rolling over and where you might need to increase or decrease. one tip from Saini was to set the fronts up for steering and the rear for tuning oversteer/understeer.
try to take a few recommendations and determine what best suits your driving abilities.
03-01-2003, 06:28 PM
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I run 36 all around with the S02's and I still haven't rolled the sidewalls over at any autox. Our autoxes are pretty high speed and the pavement is good, so YMMV.
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03-02-2003, 10:18 AM
#8
I have found the tire pressure needs vary depending upon the type of autocross course you are running.
The dinky SCCA 20-30 second runs need 41 front and 38 rear.
If you run a 1 mile course of 2 laps and times in the 1 min to 1:30 range per lap then I run 36 front and 34 rear.
I run 33 front and 32 rear on a real track.
I have found the tires seem to grip best between 35-37 degrees.
Keep in mind your tire pressures will rise as the day warms up and if you do back to back runs you may need to drop pressures between runs. You'll definitely tell if the pressure rise too much because the tires "go away" pretty definitively.
The tires are really quite good. I have just changed to GForce KDs because of the issues of finding the proper S02 and because they really weren't much more $$$. I just hope they are as consistent as the S02s were.
The dinky SCCA 20-30 second runs need 41 front and 38 rear.
If you run a 1 mile course of 2 laps and times in the 1 min to 1:30 range per lap then I run 36 front and 34 rear.
I run 33 front and 32 rear on a real track.
I have found the tires seem to grip best between 35-37 degrees.
Keep in mind your tire pressures will rise as the day warms up and if you do back to back runs you may need to drop pressures between runs. You'll definitely tell if the pressure rise too much because the tires "go away" pretty definitively.
The tires are really quite good. I have just changed to GForce KDs because of the issues of finding the proper S02 and because they really weren't much more $$$. I just hope they are as consistent as the S02s were.
03-02-2003, 04:51 PM
#9
I have found that good grip in autocross is highly dependent on getting my tires up to temp FAST. So, if it's hot outside I run higher pressure. Cold out and I run much lower pressure.
For example, this weekend it was 40 degrees out and I ran 29 front and 30 rear. The low pressure allowed the tires to heat up faster yeilding grip. However, it wasn't so low that they rolled past the rollover indicators on the tires. I feel these pressure settings helped me finish 1st, a full three seconds ahead of the second place car on a one-minute and twenty-second course.
When the temps rise I typically don't go anywhere higher than 35. Reason? Because autocross courses are SO short I don't have enough time to build up excessive heat in the tires reducing grip. These are just MY experiences...
For example, this weekend it was 40 degrees out and I ran 29 front and 30 rear. The low pressure allowed the tires to heat up faster yeilding grip. However, it wasn't so low that they rolled past the rollover indicators on the tires. I feel these pressure settings helped me finish 1st, a full three seconds ahead of the second place car on a one-minute and twenty-second course.
When the temps rise I typically don't go anywhere higher than 35. Reason? Because autocross courses are SO short I don't have enough time to build up excessive heat in the tires reducing grip. These are just MY experiences...
03-03-2003, 07:15 AM
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Approach on temp sounds good in theory, but I think two factors are more much important.
1. get enough pressure to prevent tire from rolling onto sidewall.
2. balance over/understeer.
Based on the few autocrosses I ran on S02's (and before I changed the front swaybar, I'd use 38 front, 34 rear. You need at leaset 38 front to limit tire roll under and to control push. Maybe 40 if you have not put in negative camber. 4 psi less in rear for balance, assuming stock suspension.
As to last weekend, I was getting really good grip on r compound tires and it took only about 2 corners to feel the grip come up with tire temp. S02's would take a little longer of course. I am amazed that you did not get roll under with only 30 psi. I'm not sure what you mean by rollover indicators, but scuffing should not go more that about 1/8 to 1/4 inch beyond the edge of the tread.
Gregg
QUOTE]Originally posted by Clovis
I have found that good grip in autocross is highly dependent on getting my tires up to temp FAST. So, if it's hot outside I run higher pressure. Cold out and I run much lower pressure.
For example, this weekend it was 40 degrees out and I ran 29 front and 30 rear. The low pressure allowed the tires to heat up faster yeilding grip. However, it wasn't so low that they rolled past the rollover indicators on the tires. I feel these pressure settings helped me finish 1st, a full three seconds ahead of the second place car on a one-minute and twenty-second course.
When the temps rise I typically don't go anywhere higher than 35. Reason? Because autocross courses are SO short I don't have enough time to build up excessive heat in the tires reducing grip. These are just MY experiences... [/QUOTE]
1. get enough pressure to prevent tire from rolling onto sidewall.
2. balance over/understeer.
Based on the few autocrosses I ran on S02's (and before I changed the front swaybar, I'd use 38 front, 34 rear. You need at leaset 38 front to limit tire roll under and to control push. Maybe 40 if you have not put in negative camber. 4 psi less in rear for balance, assuming stock suspension.
As to last weekend, I was getting really good grip on r compound tires and it took only about 2 corners to feel the grip come up with tire temp. S02's would take a little longer of course. I am amazed that you did not get roll under with only 30 psi. I'm not sure what you mean by rollover indicators, but scuffing should not go more that about 1/8 to 1/4 inch beyond the edge of the tread.
Gregg
QUOTE]Originally posted by Clovis
I have found that good grip in autocross is highly dependent on getting my tires up to temp FAST. So, if it's hot outside I run higher pressure. Cold out and I run much lower pressure.
For example, this weekend it was 40 degrees out and I ran 29 front and 30 rear. The low pressure allowed the tires to heat up faster yeilding grip. However, it wasn't so low that they rolled past the rollover indicators on the tires. I feel these pressure settings helped me finish 1st, a full three seconds ahead of the second place car on a one-minute and twenty-second course.
When the temps rise I typically don't go anywhere higher than 35. Reason? Because autocross courses are SO short I don't have enough time to build up excessive heat in the tires reducing grip. These are just MY experiences... [/QUOTE]