Tire Inflation: Nitrogen vs Air

We race an Arca style Super Late Model and some guys use air some guys use nitrogen. we use air, we we're out testing the other day and the tires grew to 33 psi from 24 on the right side of the car, now note that tire on the right side front sees no lower then 200 degrees F, if your street tire is seeing temps like that your having issues and the tires will fail faster then normal. the left side tires that hit about 150 degrees F and they grew from 20 psi to about 24. but again you shouldn't be seeing temps like that on street tires.