Tire pressures and care during an autox

[gunny]

Was reading in the results post about tires.
Thought I would chime in over here.
Anyhow tire care and pressures took a long time for me to figure out. Reason, was because I was trying to run pressures that the really big tire vettes are running. Front and rear in the low 30's and even in the high 20's. I tried these pressures and my car would push really bad. So I was at a practice event talking to Chris and I tried the pressures he was running, I almost hit the fence! So I went the opposite (actually put in what hoosier recommended for the weight of my car and what a difference!) My car turned really well, I wasn't killing the outside edge of the tire! I started to document what I was doing and found a sweet spot for my style of driving and for my car. In the heat of the summer I cool the tires down with water and try to get as many of the rocks scrubbed off before my next run. Sometime I'll cool the fronts and leave the rear with a little heat (my fronts get way hotter than the rear)
I think a practice event would be a great place to work on tire pressures! Try different pressures, have someone else practice with you to get more input and document what your doing! Try to simulate a race day. Do a run, let the car sit for 10 or 15 minutes, check pressures after every run and adjust.

Gunny

[Marc]

I have a twelve temperature tire pyrometer that I use for setting tire pressures. Although it's really designed to help dial in alignment settings it's still pretty useful for determining your optimum tire pressure settings.

The way it works is after a run you insert a small probe into the tire tread to read the "core" temperature at three locations on the tire: inside edge, center, and outside edge. You do this at all four corners. Basically you want to get uniform heating of the tire across it's width by adding or removing pressure. Of course, if your camber challenged (like most stock class cars are) your outside edge will always be hotter... so you then average the outside & inside temps and compare that with the middle temperatures. 

This only gets you close, you then have to add or remove pressure to balance the car to your liking.
I have the pyrometer with me at most events so if anyone wants to try it, come ask me for it!

[bobzdar]

Are you both running A6's?

[gunny]

Yes, I'm running A6's.
What a difference they make. Last year on a practice day I did 3 runs with street tires then changed over to the A6's and wow! Around 2.5 seconds difference!

Gunny

[whiteryder]

Yes, I'm running A6's.
What a difference they make. Last year on a practice day I did 3 runs with street tires then changed over to the A6's and wow! Around 2.5 seconds difference!

Must.... resist.... must....

[gunny]

Yes, I'm running A6's.
What a difference they make. Last year on a practice day I did 3 runs with street tires then changed over to the A6's and wow! Around 2.5 seconds difference!

Must.... resist.... must....

Just give in to the dark side! rcrack is the way to go.