Tire Pressures for AutoX

///MSH · 11-17-2011, 10:22 PM

From what i've seen here, it seems there are more road course guys than AutoX Guys...this might be an interesting poll.

In any case ...this thread is full of good advise. I will add a few bits that I haven't seen already discussed that i believe to be relevant factors. All in all, i think there are too many variables to answer the question cart-blanc.

You need to consider your track surface - it is just as relevant as the tire compound. I will run higher pressures on a surface will more grip.....generally speaking concrete has more grip than asphalt. Similarly, sealed asphalt is different than unsealed....you get the picture.

You need to adjust based on the course layout - Just as most people think about F/R differentials, you need to look at L/R. most autoXes, like road courses are either CW or CCW....as such you will see your pressures change from side to side.

I agree with those who use the factory marks that point to the edge of the tire. I take this a bit further. I use the marks on the front. And tune the real relative to the front depending on whether the track puts my car into a natural understeer or oversteer condition...if you think in extremes...the F/R differential is not unlike adjusting swaybar stiffness. Anyway, I say "natural" because throttle-endused oversteer can be fast or slow depending on when/how the driver chooses to employ it. When looking F/R, on tight asphalt courses, i have found that low thirties work well with about 1PSI more pressure up front.

As a passing thought, i subscribe to taking pressures/temperatures when i come off course only because i believe this is more indicative of what the temps/pressures will be when i'm on course. Also, specific to termperatures, I have found that R-Compounds will retain the heat longer than 140 or 180 treadware tires.....the point, if you have street tires, you'd better measure temperature quickly or the tread surface has alreay cooled down significantly.

Hopefully these thoughts will give you more to think about.

Cheers

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11-17-2011, 10:22 PM	#22 (permalink)
///MSH Base Member Join Date: Jul 2011 Location: Owasso, OK Posts: 86 Drives: '11 370Z Nismo Rep Power: 14	From what i've seen here, it seems there are more road course guys than AutoX Guys...this might be an interesting poll. In any case ...this thread is full of good advise. I will add a few bits that I haven't seen already discussed that i believe to be relevant factors. All in all, i think there are too many variables to answer the question cart-blanc. You need to consider your track surface - it is just as relevant as the tire compound. I will run higher pressures on a surface will more grip.....generally speaking concrete has more grip than asphalt. Similarly, sealed asphalt is different than unsealed....you get the picture. You need to adjust based on the course layout - Just as most people think about F/R differentials, you need to look at L/R. most autoXes, like road courses are either CW or CCW....as such you will see your pressures change from side to side. I agree with those who use the factory marks that point to the edge of the tire. I take this a bit further. I use the marks on the front. And tune the real relative to the front depending on whether the track puts my car into a natural understeer or oversteer condition...if you think in extremes...the F/R differential is not unlike adjusting swaybar stiffness. Anyway, I say "natural" because throttle-endused oversteer can be fast or slow depending on when/how the driver chooses to employ it. When looking F/R, on tight asphalt courses, i have found that low thirties work well with about 1PSI more pressure up front. As a passing thought, i subscribe to taking pressures/temperatures when i come off course only because i believe this is more indicative of what the temps/pressures will be when i'm on course. Also, specific to termperatures, I have found that R-Compounds will retain the heat longer than 140 or 180 treadware tires.....the point, if you have street tires, you'd better measure temperature quickly or the tread surface has alreay cooled down significantly. Hopefully these thoughts will give you more to think about. Cheers