Originally Posted by
DrIsotope
Tire places hawk nitrogen to drivers because it leaks out of the tire much more slowly than atmospheric air. It's also dry, which is a good thing for tires. Nitrogen-filled tires can go 6+ months with no loss of pressure.
Race cars use nitrogen because it doesn't react nearly as much to changes in temperature. I did tire and suspension setup as part of a short-track pit crew for several years. Tires filled with air could swell by +10psi as the tire heated from ambient to +180º. The same tire filled with nitrogen would only change 1-2psi. Higher pressure changes the rollout of the tire, which changes the stagger of the tires (for circletrack racing, the tires on the left are smaller than the tires on the right) which alters the handling of the car.
I'd love to be able to fill my tires with nitrogen. Dry, leaks out more slowly. No real drawbacks.
The advantage seems minute to only matter for racing teams. For those there also is a safety advantage - in a fiery crash the burning tires wouldn't release oxygen into the fire. But for normal life it wouldn't matter. Air contains 78% nitrogen. If it was true oxygen leaks significantly more, the tire would have an increased nitrogen level after some fill ups.
The scam tire places also don't evacuate the tire first. You go there with a tire and they MAY let the air out to 0 psi (which is 14.7 psi absolute pressure). then fill with nitrogen to 30 psi or whatever you car needs (44.7 psi absolute). so you may have a third air, and 2/3 of nitrogen. they may also only top off your tire, so you may have 79% nitrogen compared to 78%. they also are not likely to use lab grade nitrogen, so maybe you get 95% nitrogen.