Science of Speed: Tires and Pressure

NASCAR tires don’t have “air pressure” because they’re filled with nitrogen. The culprit responsible for increasing tire pressure during a race is friction. Using dry nitrogen gas helps the team predict how hot the tire will get and how much the pressure will “build” during a race.

http://science360.gov/obj/video/11ac7bf2-11dd-4df2-8524-373accf09dbd/science-speed-tires-pressure