You Asked:
Why are racing car tires filled with nitrogen? — Midhun, Palakkad, India

Marshall Brain Answered:
There are supposed to be a number of benefits with nitrogen-filled tires. Everything from fire-prevention to rust-prevention to leak prevention to more consistent tire pressures. This video talks about some of the benefits:

But… a lot of this is snake oil stuff. The effects are so small that they would probably be unmeasurable.

If you fill your tire with normal compressed air, it is about 80% nitrogen to begin with. When you put in pure nitrogen, you are eliminating two things: oxygen and humidity. It could be argued that oxygen and humidity can increase the rate of corrosion, but when was the last time you saw a rusted wheel? Aluminum wheels don’t corrode, and steel wheels are treated to prevent corrosion. It could be argued that a tire filled with nitrogen will leak more slowly than a tire filled with air, but tires leak. You still have to check the pressure periodically and top up. The difference is infinitesimal.

Why are racing tires filled with nitrogen? It certainly doesn’t hurt, and it sounds cool and techy, and there might be some tiny benefit. Who in the world of racing is going to pass up any possible benefit?