Tire pressure recommendations for autoX

[jdgamble]

Hey all. I’m doing my third autocross this weekend in San Francisco. Any recommendations on cold tire pressure? The temp will change significantly from when I leave my house until when I get there. But I should be able to get close.

Non-ZCP.
19”, so BMW rec is 32

Thanks.

John

[Gomeler]

Guaranteed someone in the pits will share a gauge and compressor, can't imagine autox guys are any less helpful than road course guys.

Can't comment on pressures, don't do autox, but I would imagine given zero warmup, you'd want pressures for your first pass to be almost at your ideal hot pressure, and you'd bleed pressure during the day as you get a little residual heat in the tire.

[edkwok99]

It depends on your tires. In general, 35psi hot should accommodate most setup.

[F80Speed77]

200TW tires like to be around 32-35 hot.

>200TW tires will need more tire pressure to mitigate sidewall flex and you may be somewhere between 35-40hot.

You'll want less pressure in the rear to help with oversteer.

Go pick up a nice digital tire pressure gauge and pump, Craftsman makes some nice ones. Good luck and have fun!

[M4gtr]

When I ran mp4s tires I started at 30psi front and 31psi rear. As the tires got hot, more grip, more air I'd adjust. I would then bleed off depending on if I had understeer or oversteer.

[jdgamble]

I started 34/35 and it worked out ok. My best lap was a rerun after not getting a time. The extra heat helped I think. I had a totally respectable day. Very competitive with the Vettes. I was within 3 seconds of a GT3RS, and people were talking about how good the driver is. I could drive on a track all frickin day and never get bored.

[chrisjguzman]

I run between 29 -30 psi cold but I run a few more psi in the rear to get her to rotate more.

[jmg]

I drop 4-5 psi cold all around (28-29 psi cold) and adjust here and there if it gets above 35ish hot. I have -2.7 front camber and I have lots of front grip and plenty of torque to swing the back around and I would rather have corner exit grip for acceleration.