Hey guys, the air that we breathe is 79% nitrogen, 20% oxygen, and 1% other gases.
Any shop that puts nitrogen in the tires is putting in pure nitrogen to eliminate the oxygen, which is responsible for the higher rate of expansion and contraction with changes in temperature. In theory, the nitrogen is less prone to leak out of your tires and gives us less to worry about. I have tried it before and there is less pressure loss over time but that is the only thing that I have noticed, since I can't sense the changes in the tire pressure as the tires heat up.