This summer (Atlanta temps in the mid 90s, pavement around 135?) I had the tire pressures about where I wanted them - Hoosier AS06 225/45-15s.

Any suggestions for pressures for the next event which will be most likely in the 70s or maybe even slightly cooler?

Is there a starting "rule of thumb" I can apply? Like an amount for each 10 degrees?

 

70 degrees = cold

You might lower your rear pressures a little. Now keeping in mind that I used to live in Minnesota... In really cold weather (probably 50 degrees or less), I run something like 25psi in the rear.

The mini heats the front tires pretty quickly, but the rears don't do much and so they don't heat up. This can make for a mega-tailhappy car halfway through your run when the fronts are at operating temp and the rears are still stone cold. So you have to compensate by running the rears really low.

For 70 degrees, though, you wouldn't need to do anything like that. Once it's above like 60 degrees, I always run the same pressures more or less.

I've been at autocrosses where it was snowing. Now THAT'S a cold autocross!

 

Umm, I said cooler, not cold...

So basically, are you saying that if I set the cold pressures on a cool day with cooler pavement the same as I do with cold pressures on a hot day with hot pavement, it'll be ok?

I'm surprised at that a bit, since the pavement won't heat them up as much on a 95+ degree day.

 

You might start with the rears a couple psi lower than normal. Depending on the number of runs, or if you are a two driver car, once the rears have some heat in them you can start letting them climb up to your normal pressures.

Just be ready for a change in behavior during your first run or two as the delta between Front/Rear tire pressures changes as the fronts warm up faster.

Scott
90SM

 

Thanks!

Sounds like a plan.