Welcome to Brainstuff from house stuffworks dot com where smart happens. Hi. I'm Marshall Brain with today's question, why don't they use normal air when they pump up race car tires? Many race car teams use nitrogen instead of air in their tires because nitrogen has a much more consistent rate of expansion and contraction compared to the normal air that we breathe. Often, a half pound of pressure will radically affect the traction
and handling of a tire. With track entire temperatures varying over the duration of a race, the consistency of nitrogen is needed so that the team and the driver can maintain their sanity. Nitrogen pressure is more consistent than normal air pressure because air typically contains varying amounts of moisture due to changes in the relative humidity on race day. Water in the air causes that air to be inconsistent
in its rate of expansion and contraction. So a humid race in the southeast United States or a dry race in the desert western United States could make for unpredictable tire pressures as the tires heat up and cool down during the race. If you use dry nitrogen, which contains no humidity. You don't have to worry about these inconsistencies. Nitrogen is also used in the high pressure tires of
large and small aircraft. It turns out that many tire shops will now sell you nitrogen filling for your tires if you're willing to pay extra for it. Is this a good idea? Chances are, in your normal day to day driving, a little bit of tire pressure change isn't going to make that much difference to you, if any at all. And the other ideas that a tire shop will use to try to sell you the nitrogen usually
are red herrings. They'll talk about things like rust your inner rims, or attacks by oxygen atoms on the inner part of the rubber of the tire, all kinds of stuff. Almost all of this falls into the category of urban legend. But if you want to pay extra for dry night virgenior tires, it certainly isn't gonna hurt anything. For more on this and thousands of other topics, doesn't how stuff works dot Com, and don't forget to check out the brain stuff blog on the how stuff works dot Com
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