Tire Pressures

[extremez31]

Hey Guys, In preparation of the fist event of the 2013 season, I am dialing in my M2. Thanks to everyones help I have got the car aligned and now need help with a starting point for tire pressures. Any good stating points front / rear?

Running STF 15x7 wheels Kumho Ecsta XS Tires, -2 front camber, 0 toe. Eibach coilovers 450LB front 500LB rear

 

[Jond63]

I'm going to try 38psi front and 34psi rear to start...

 

[CorkSport]

I was running 38 front and 40 rear running the EXS tires in STF and it was a good starting point. I was running a different suspension setup though.

-Derrick

 

[eyeballs]

I think I ended up pretty close to 35 front and 37 rear on my s-drives last time, but they weren't broken in yet. On my NB with the XS's I was lower, maybe 31-32. Since I doubt you'll have issues finding rotation, maybe 33-34 even front and rear??

Disclaimer: My pressure guage is cheap and not entirely accurate, but its consistent and thats all I need. I think it reads a 2-3 psi low so keep that in mind.

 

[extremez31]

Afternoon Fellas, So I didn't check this post prior to the event kind of winged it on pressures.

I ran 31 PSI Front 33 PSI Rear. My first run of the day I ran 54.495 every run after that was in the 60's. I had a co driver which broke into the 59's at the end of the day. Timing and scoring were having issues all day so they discounted the 54.495 because "I was unable to back it up, they chalked it off to a timing error" They did not delete my time until after the 2nd heat where i went from 22nd in PAX to 88th with 121 drivers.

The car wasn't turning in and pushing everywhere after the first run...

I went home and swapped wheels and tires and noticed that my front spring perches unlocked and that the car sat approx 3/4" lower on both sides. Also tire pressures were way to low.

So this saturday I am going very prepared making sure everything is 100% between runs. Will start with 36psi front 38psi rear

 

[racercentral]

So many different ideas on tire pressures. Same front and back? More front? More back?
After the usual rounds of mistakes, I use 36 front & 40 rear in autocross. Don't know if its good or bad, but it seems good.
On the track, its 35 front, 32 rear. Last year was Dunlop Stars. This year will be the new Dunlop IIs. Tried adjusting the air pressure down before each track session based on the increased pressure from heating in the previous session, so I would have even starting pressures. Didn't work so hot. Last sessions got slower because the air pressure ended up lower. I was confused too. So now just set the pressure once & leave it alone, although I log the pressure changes after and before each session. Seems to work better.

 

[extremez31]

I ended up running 44 front 46 rear. It was 50 degrees out.

 

[jasyatz]

Richard,
Thanks again for the keys...Car is an absolute blast. Balance was very good with those pressures, car seemed to be very happy. If only I could have gotten used to the lack of ABS, who knows what that last run could have been.

And yes, I'm trying to find my own M2 now...See you at the Evo School..

-Jeff

 

[extremez31]

Hey, I didn't think you were going... I sourced 600# springs for the front, got an engine mount I need to install, bought a Schroth harness (after lending me your torso strap, this is essential to focusing on going fast) also bought a go pro. Lets see how far I can progress at the evo school.

Are you instructing? if you are Ride with me I really did appreciate all of your input and teaching style.

I'm surprised you feel that the car is that good. It had nothing but coilovers.

it'll be interesting to see what the 600# springs do. Hollis ran 550's in the front. No rear bar and stock front.

You were significantly faster in the mini, I believe by 2 seconds no? you mini is prepped for H stock, right?

Hopefully the stiffer springs help some of the nose dive. Camber is set at -2 in the front. Will have it closer to -3 for the class. Will start with the same pressures in tires.