lobuxracer

iTrader: (2)

It isn't nitrogen that makes the difference. It's no water in the air. Air compressors compress whole air which includes water vapor. The water is more reactive to heat and raises pressures faster than dry nitrogen does. You could do the same thing with air that has been "dried" properly, but it's pretty simple to evacuate a cylinder, drop in some liquid nitrogen and let it return to ambient temperature which gives a tiny fraction of the water vapor you would get with normal compressed air.

If you are having wear issues, raise your pressure so you are seeing the maximum pressure on the sidewall and see if it helps. Ideally, you measure temperature and compare the temperature to the known good range for the compound you are running. If the tire is too cold, lower the pressure to get more flex in the rubber and build up more heat to get the compound delivering what you need. If the temperature is to high, add pressure to reduce flex and get the compound out of the greasy range.

I have a really solid book on race car engineering. The first half of the book (it is rather thick) is devoted to understanding tires, reading tread wear patterns, and developing an understanding that everything you do with the car is to make the tires work better. They are the most critical part on the car from a performance perspective. Power without traction is useless...

Mingofish

^^^ thank you Lance, good info.

I think my AD08R are holding up really good and giving relatively even wear.
Been trying to keep the tires at 40-42 max.

Haven't started measuring actual tire temp but will be on my next outing.
I'm messing with camber now so I wanted to know inner vs outer tire temp.
Is there a way (web site?) to know what the optimum temp is for a particular tire less than calling manufacturer and asking?

ghoffner

Cold 27, hot 36-38. This was in Austin at COTA.

I thought that was a little low, but some really experienced track guys were saying to keep it there...so I listened.

Mingofish

Man that's a huge difference from cold to hot.

i think 36-38 is ok as long as your side wall isn't rolling over.
The edge of most tires have triangle indicators that are there for that exact reason. If you start driving on your side walls, the triangles will wear away. Look for those to see where you stand.
I think a lot of seasoned track guys who run track tires tend to stay at 35-38 but that's because most track tires have stiffer side walls.
Regular street tires have softer side walls for better ride quality, therefore roll over easier. Takes more pressure to keep em up right. Like Lance said, prob around 40+ to be able to keep them stiff.
Check the triangles.

lobuxracer

iTrader: (2)

Stiffer sidewalls on racing focused tires isn't exactly true. Proper slicks have surprisingly soft sidewalls, and are very easily damaged if you hit debris, which is just one of the reasons racing slicks are a really bad idea on the street.

If you really want to get serious, contact the tire manufacturer and get the temperature numbers for your make and model of tire. Adjust your pressures (and alignment) to get (as best you can) even temperatures from the inside to the outside of the tread within the range the manufacturer says are good temperatures for the compound you are running.

There are LOTS of "rule of thumb" approaches out there. At the highest levels of racing, it's all about acquiring the data and adjusting for the right numbers in service.