Front/Rear Tire Pressure for Auto-X

[RaverChankoMX3]

I was reading an article about how to improve FWD cars on autocross events and they mentioned raising tire pressure to near the maximum pressure to prevent tire roll. Secondly, to help prevent understeer, they recommended dropping the psi in your rear tires at least 4 psi from whatever setting you have on your front tires.

Now, I do not know the max capacity but just to throw up some numbers (borrow what they used) They said something like 42psi Front / 38psi Rear.

What say you?

[TsiMiata]

I set them by looking at tire roll over. I usually start ~40psi front and rear. Then do a run and look at the tires. you'll see how far onto the sidewall your going. Your tires will have a little arrow on the side near the edge of the tread. Thats where you want your tire rolling over to. If your not rolling over enough take some pressure out, if your to far down the sidewall add some pressure.

Be sure you have a good alignment to. If your camber is to far out of whack this method won't work. If your autocrossing 1/2-1 degree of negative camber is a good compromise for a car that will see mostly street duty. I like the front toe set at 0 or 1/16" toe in. But for best performance in autocross you want toe out. but toe out makes the car very darty when driving normally.

[RaverChankoMX3]

TsiMiata~~

Thanks. So do you also lower the rear tires to 4psi less than your front as that article suggested?

But yea, I'm no where near starting to want to mess with camber/toe and such. It just looks like a lot of fun and I'm trying to study up on it so I don't embarass myself too badly

~CHANKO

<small>[ March 12, 2004, 09:45 PM: Message edited by: CHANKO ]</small>

[TsiMiata]

I wouldn't put much faith in that 4psi #. It really depends on your alignment, shocks, sway bars etc.. My car has a very bad alignment right now. The rear has way to much positive camber. So I have to run my rear tires 4psi higher than the front.