umm well regular atmospheric air will fluctuate roughly 1 psi for every ten degree temperauture fluctuation and nitrogen changes 1 psi for every 100 degree temperature change ....thats all the advamtage of having nitrogen in yoru tires does.....as far as pricing....its wicked cheap most tire places will do all your tires for like 10 dollars or some will throw it in with the purchase of a new set of tires i dunno its a really inexpensive thing to have done

 

o ok cool... thanks a bunch