Autocross Tire Pressure on ZII's

[Areddi]

I did a bit of searching, and see that most people seem to have some info on tracking, and on autocross on stock tires. I am looking to see if anyone else has any experience autocrossing on ZII's yet and what pressure you ran.

I have 225/45's on a second set of stock rims, and have done one event on them. I ran 40 lbs square, but kicker is that it was 35 degrees out that day, so I am fairly sure my experience was not "normal". 40 lbs square seemed to do alright, but I am thinking of going for like a 41ish front and 36ish rear for my event tomorrow since the temperatures are getting back to a reasonable level.

Anyone thoughts or opinions? I am stock suspension other than the Stranoparts 22mm front sway, which I installed after my last event as well.

[Biggins]

I think you're a little high. I've liked 35-36F/33-34R but I'm on 215s. I'll be there tomorrow too, so maybe we can compare notes?

[Ranatsu]

On the first gen StarSpecs similiar setup as you, 225/45 stock wheels. I ended up running closer to 35 in the front and 32-3 in the rear. If I ran any higher in the rear I just had loads of wheel spin.

I started at 40lbs same as you and had to bleed out a lot to get the car to hook up at all. Even at lower pressures I wasn't having any problems with the tires rolling onto the sidewall. I was also running in significantly warmer temps than you.

[Scooby South]

38-36Front/36-34Rear depending on how you like the car to feel

[Sam Strano]

Originally Posted by Areddi

I did a bit of searching, and see that most people seem to have some info on tracking, and on autocross on stock tires. I am looking to see if anyone else has any experience autocrossing on ZII's yet and what pressure you ran.

I have 225/45's on a second set of stock rims, and have done one event on them. I ran 40 lbs square, but kicker is that it was 35 degrees out that day, so I am fairly sure my experience was not "normal". 40 lbs square seemed to do alright, but I am thinking of going for like a 41ish front and 36ish rear for my event tomorrow since the temperatures are getting back to a reasonable level.

Anyone thoughts or opinions? I am stock suspension other than the Stranoparts 22mm front sway, which I installed after my last event as well.

You mean in DC @ FedEx? I'll be there, I think I'm running 2nd group in Super Stock. I can help if you come find me (assuming you aren't running like last). I think it's high, but can help read the tires for you

I'd say more like 36 front, 34 rear or so would be more like where I'd start.

[Areddi]

Originally Posted by Sam Strano

You mean in DC @ FedEx? I'll be there, I think I'm running 2nd group in Super Stock. I can help if you come find me (assuming you aren't running like last). I think it's high, but can help read the tires for you

I'd say more like 36 front, 34 rear or so would be more like where I'd start.

Yep I'm running STX so we're first group out. If your group 2 you'll be working while I run. Get to watch your sway bar in action. It's awesome by the way!

I would love some help reading the tires. I'll trying going down to like 36ish like you guys are suggesting.

[whataboutbob]

Let me preface this with the fact that I'm still an AutoX n00b. I'm on 245/40/R17 Z2s with 17x9 RPF1s.

I've tried 36 square, 40F-34R, 34F-40R, 39F-34R.

These were on relatively cools days down in San Diego on both the SE and NW lots. Our surface is "rough" asphalt.

I only had -1 3/8 camber in the front and I was trying to keep the front pressure up to keep from running so far down on the front sidewall. I've since put the COMCs on the front but haven't taken a camber measurement.

The high pressure in the rear seemed to make the car rotate a LOT. The square setup seemed pretty good. The high pressure in the front seemed to make the car plow.

I just got a portable compressor which should allow me to more easily adjust the air pressure at the events. I think that I'll probably start my next event at 38F 34R and see where it goes from there.