[TriKKy]

So here is a question I've always had about this:

If Nitrogen doesn't expand and contract as much as regular air, then what pressure should you fill your tires with?

Arguably, it should be higher than the manufacturer's recommendations because those recommendations are based on the fact that once the air in the tire heats up the pressure in the tire will increase to "optimal." If that's the case the best thing to do would be to fill tires with air to manufacturer's specs and then heat them up and measure the pressure when hot. Then shove the Nitrogen in up to the heated "optimal" pressure.