I have been rebuilding my 86 Na 6 port engine for the last three weeks. I'm just about finished and the first Autocross race of the season is two weeks away!!!!!!!! Can someone tell me about the range of tire pressure I should start out with. I know it will vary given conditions at the race, but I don't want to show up completely unprepared. I've got 255x55x15 tires on 6.5"? wide aluminum wheels.

 

i'm pretty sure most autox guys run high tire pressure like 50psi! i am not 100% sure since i have never autox'd

 

Vosko, you're right, for street tires, most people raise up the pressure. I don't know about 50... I started at 40 and settled down to around 36 in the front, 34 in the back for my best runs. That was on a warm day with 205/40/17's. With my sidewalls so short, I didn't need to have the pressure jacked up too much.

 

run 40 initially...

use the chalk test to adjust thereafter..

 

Amp, I did the chalk thing too but what exactly am I looking for... just how much is wearing off up the sidewalls? Not much was wearing off at all so I was lowering pressure.... is that right?

 

255/55/15's on 6.5" wide rims? Are you serious or is that a typo? 205's are as wide as you want on a 6.5" rim.

 

if your noticing shoe polish or chalk off from your sidewall markings...

youll need to increase your tire pressure...

 

everytime i've auto crossed, I always start out at about 30psi then adjust after each run, as they heat up i drop it down to usally around 28 when they're hot



ps I'm running BFG euro T/A's 195-50-15

 

yeah my jaw dropped when I read that.

 

Yeah, Amps got it!

Start them out around 40, chalk it,

Drop it a few psi, until you notice chalk missing.

Yeah. . and about the 255, Yikes!

I'd be a little nervous about that, Unless those sidewalls are MEGA reinforced they're gonna role!