Jims5543 wrote:Anyone else have nitrogen in their tires?
Yeah, those of us who don't want to waste money on 100% nitrogen have 78% nitrogen in our tires (i.e., air). Pure nitrogen has only one advantage over air: the nitrogen molecule is slightly larger than the oxygen molecule so it diffuses through the tire's rubber and porous alloy wheels a little bit more slowly. Because air is only 21% oxygen, this affect is usually unmeasurable.
The pressure of all gases changes with temperature to exactly the same degree, so inflation pressure in a tire filled with dry nitrogen changes by the same amount when the tire's temperature changes as does a tire filled with dry air. However, most, but not all, compressed air, can contain water vapor because it wasn't dried when it was compressed. Water vapor can condense when a tire cools which would cause the inflation pressure to drop more than a tire filled with any dry gas, including nitrogen or air, or any liquid water in a tire could vaporize when a tire warms which would cause its inflation pressure to increase more than a tire filled with any dry gas.
Nitrogen might make sense in tires used in competitive racing where inflation pressures might need to be carefully controlled and matched. But in a street vehicle, the small advantages of dry nitrogen don't justify its cost.