Tire pressure?

[skinsfn36]

So I've read a couple different things, for a FWD car that tends to understeer a ton, would you be better off with low pressure in the front or rear....stock tire pressure is 32psi front/28psi back I believe.

[blue06civic]

What kind of car?  To couteract understeer, I'd run higher pressure in the rear tires.  I used to run a Saturn SL2 on street tires and would run ~40psi in the front and 50psi (sometimes more) in the rear.  I'd just drop the backs down to 40 when I was done for the day and drive back home.

[skinsfn36]

It's an 06 Civic Si, it's on some aggressive street tires. So maybe crank the rears to about 40psi, then drop it at the end of the day?

[blue06civic]

I would run the rears higher than 40psi.  Look at the max pressure on the sidewall of the tire.  Most are 44psi.  Pay no attention to the manufacturer's recommendation.  That setting is a compromise meant to preserve ride quality.  If you leave the fronts too low (32psi is usually too low), the sidewalls will roll over under cornering and you can chew them up pretty badly.

Short of finding someone fast running the same setup you are and copying them, my recommendation would be to start at 40psi in both the front and rear tires.  See how it feels, then jack the rears up to 46psi or so and see how it changes the dynamics of the car.  If it feels better you can try playing with the amount of stagger and seeing if it feels better/worse.  You can also then try and drop everything by 5psi and see what happens...so something like this:

run 1 - 40/40
run 2 - 40/46
run 3 - 35/41

You can either bring a pump or air tank with you or borrow someone else's.  My bet is that running the fronts between 36 and 42psi and the rears between 42 and 48psi is going to be the best.  Don't worry about exceeding the max tire pressure by several psi while you are autocrossing, but don't drive around on the street like that too much.

[skinsfn36]

Thanks for the suggestions man, I see you own an LX, maybe if they give them to us you can take a fun run in my Si to feel the difference.

I'll be bring a little cig. lighter compressor pump for the event.

[blue06civic]

Thanks for the offer.  I may have to take you up on it   See you out there!

[skinsfn36]

Will do, what do you drive, are you Justin with the K-swapped hatch?

Sorry, just trying to put a face to a name.

[blue06civic]

I am the one with the K-swapped hatch.

[skinsfn36]

That's what I thought, we talked for a bit at one of the events last season. I'll be seeing you on the 21st then!