Nitrogen is used in tires for two reasons:
1. Air compressors tend to allow moisture into the air stream. Moisture tends to yield a more sensitive pressure response to temperature (water can condense or vaporize with temperature changes).
2. Rubber is less permeable to nitrogen than it is to other components of air.
The inherent response of a gas pressure to temperature is, in fact, independent of the composition of the gas. That’s basic kinetic theory (from which the ideal gas law is derived). Filling with dry air would give the same result as filling with nitrogen as far as pressure response is concerned.
Yes. Thank you. I knew about the permeability and rubber, and knew it was moisture in normal air compression vs. nitrogen, but failed to point that out. That lack of moisture is what helps the nitrogen-inflated tires remain at a more constant pressure.