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MS6 Autocross tire pressures

2K views 9 replies 5 participants last post by  FormulaLT1 
#1 ·
I have recently installed 235/40/18 BFGoodrich T/A KDW2's on my MS6. I plan to AX the car this Saturday at a Porsche club event. The tires feel squishy now at 40 PSI do I dare go higher?

Any recomendations on pressures for front and rear tires?
 
#4 ·
If you have a large capacity air tank, start at 40psi and like nextstep said, chalk the tires and if it rubs off the chalk lines on the sidewall at all, increase the psi until it stops. if you look around at everyones tires, someone will like be doing the same thing. I started with 45 in front and rear after getting my new tires and lowered until where they were rubbing on the shoulder where I wanted it. by the end of the day I had just 35 in the front and 32 in the rear. but then I have very stiff tires. you can go up to whatever the sidewall says is the max psi when the tire is cold. pressure will increase with temp of course. the MS is heavier and those BFGs are soft on the sidewall so you could start at 50/45 and work your way down. just don't forget to regulate the pressure before you drive home or you'll wear the center out of 'em.
 
#5 ·
If you have a large capacity air tank, start at 40psi and like nextstep said, chalk the tires and if it rubs off the chalk lines on the sidewall at all, increase the psi until it stops. if you look around at everyones tires, someone will like be doing the same thing. I started with 45 in front and rear after getting my new tires and lowered until where they were rubbing on the shoulder where I wanted it. by the end of the day I had just 35 in the front and 32 in the rear. but then I have very stiff tires. you can go up to whatever the sidewall says is the max psi when the tire is cold. pressure will increase with temp of course. the MS is heavier and those BFGs are soft on the sidewall so you could start at 50/45 and work your way down. just don't forget to regulate the pressure before you drive home or you'll wear the center out of 'em.
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Thanks I ran 45 front and 43 in the back. I was getting a some rollover from one hard left hand corner so couldn't go any lower.

Here is a hilarious picture of the car being hauled down from about 85 MPH to 30 MPH for impending left hand turn. Talking about weigh transfer! :D

 
#7 ·
holy crap. front sway bar might help. stiffer springs too
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LOL! I'm a rather aggressive driver. I think some better springs would help with the weight transfer under heavy braking. It was a blast smoking $80K Porsches with DOT R tires etc in a stock MS6 on street tires. I had a friend that showed up in a Firehawk. We were cracking up the entire day because it was a HP course on the first section we were able to stay competive with Porsches. I had his time until the last run (8 total runs) checkout front end lift on his car! He beat my time a several hundreths of a second. Tough to beat 350 HP at the wheels.

 
#8 ·
Looks familiar...

60MPH to a 10MPH wagon wheel braking to late, stock suspension and forgetting to wear my helmet :)
 

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