The local Saturn dealer is now putting nitrogen in their vehicles tires before delivery for what I believe was a $20 charge. I don't think it was per tire, but I'm not possitive. It's not something being published or advertised in our area yet. That being said, if you had low pressure on one of your tires you might have problems with getting it repressurized due to the fact that most dealers or tire shops are not using nitrogen yet. If you have your tire repaired out of town chances are you'd have to have it filled with air and then when you got back in town you'd have to take it to your dealer or local tire store that carries the nitrogen and have it recharged.
Heat and cold does affect the nitrogen somewhat. If you follow racing at all you will hear the commentators talk about the cars bottoming out or having tire rub when new tires are put on the cars due to the tires having low pressure. after a few laps on the track under racing conditions, the tires build up some heat and the pressures go up. Tire pressure changes are not near as noticeable with nitrogen as they are when using regular air.
Heat and cold does affect the nitrogen somewhat. If you follow racing at all you will hear the commentators talk about the cars bottoming out or having tire rub when new tires are put on the cars due to the tires having low pressure. after a few laps on the track under racing conditions, the tires build up some heat and the pressures go up. Tire pressure changes are not near as noticeable with nitrogen as they are when using regular air.
