True, true and unrelated.
Air, as shipped from the factory (unless you have NOS air from Germany it
come from Taiwan or Brasil now) is a mixture of ALL gaseous elements, 21% O2,
78% N2, 1% everything else, generally, with a highly variable amount of H2O
vapor. The water vapor is the most heat-reactive and the dryness of the
nitrogen fill is probably what would make any difference in tire heating/
pressure. In the long run the lack of oxygen would help preserve the tire;
oxygen oxidizes (burns) most other elements at a steady rate that also
depends on the temperature (even if it's not on "fire").
Even better than nitrogen would be a truly inert gas with a higher molecular
weight, like argon. This might get expensive, though.