Basic newbie autocross question, Tire pressure |
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Basic newbie autocross question, Tire pressure |
jd66921 |
Feb 27 2008, 07:59 PM
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#1
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Member Group: Members Posts: 316 Joined: 9-January 06 From: Texas Member No.: 5,394 |
Hi,
I recently started autocrossing my 914. I enjoy it a lot! The car is not really set up for autcrossing, no sway bars, standard alignment, etc, but it is still fun to see what I can do. The tires I am running are Kuhmo street tires. I know they are not optimal, but I am not ready to upgrade. The issue is trying to optimize tire pressure. I know the 914 is a very light car and therefore may not need a lot of pressure. I ran them originally at 35 psi. That seemed okay. I ran them up to 40 psi, and while fun to slide around, it was way too much! I am now running 32 psi, and I don't know if I should go lower or not. How does the pressure vs cornering curve go? I would think the cornering force would increase with tire pressure up to a point, and then tail off. Any ideas what the range should be? 25-35 psi? Higher? Lower? I'm just looking for general guidelines. Tires are 195/50's on 5.5 inch fronts and 6 inch rears at the moment. Thanks, Jeff PS: Autocross video |
Joe Ricard |
Mar 7 2008, 06:41 AM
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#2
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
When you get comfortable with the car you will find tat your car will like to have you put your foot down as the back end s getting out of shape. What it will do is transfer weight to the rear wheels and make them grip.
I wa riding with a new guy that kept lifting his foot mid apex because the car was sliding the tail. I holllered "GAS GAS" he gassed it the car stuck and scooted right in the intended direction. He was like wow that was cool. Which leads to throttle lift oversteer Nuff of that as I am rambling. Yes there is a bell curve for grip vs air pressure. but it is also dependant upon suspension and body roll. |
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