WEBVTT - Why don't they use normal air in race car tires?

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<v Speaker 1>Welcome to Brainstuff from house stuffworks dot com where smart happens. Hi.

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<v Speaker 1>I'm Marshall Brain with today's question, why don't they use

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<v Speaker 1>normal air when they pump up race car tires? Many

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<v Speaker 1>race car teams use nitrogen instead of air in their

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<v Speaker 1>tires because nitrogen has a much more consistent rate of

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<v Speaker 1>expansion and contraction compared to the normal air that we breathe. Often,

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<v Speaker 1>a half pound of pressure will radically affect the traction

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<v Speaker 1>and handling of a tire. With track entire temperatures varying

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<v Speaker 1>over the duration of a race, the consistency of nitrogen

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<v Speaker 1>is needed so that the team and the driver can

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<v Speaker 1>maintain their sanity. Nitrogen pressure is more consistent than normal

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<v Speaker 1>air pressure because air typically contains varying amounts of moisture

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<v Speaker 1>due to changes in the relative humidity on race day.

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<v Speaker 1>Water in the air causes that air to be inconsistent

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<v Speaker 1>in its rate of expansion and contraction. So a humid

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<v Speaker 1>race in the southeast United States or a dry race

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<v Speaker 1>in the desert western United States could make for unpredictable

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<v Speaker 1>tire pressures as the tires heat up and cool down

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<v Speaker 1>during the race. If you use dry nitrogen, which contains

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<v Speaker 1>no humidity. You don't have to worry about these inconsistencies.

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<v Speaker 1>Nitrogen is also used in the high pressure tires of

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<v Speaker 1>large and small aircraft. It turns out that many tire

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<v Speaker 1>shops will now sell you nitrogen filling for your tires

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<v Speaker 1>if you're willing to pay extra for it. Is this

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<v Speaker 1>a good idea? Chances are, in your normal day to

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<v Speaker 1>day driving, a little bit of tire pressure change isn't

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<v Speaker 1>going to make that much difference to you, if any

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<v Speaker 1>at all. And the other ideas that a tire shop

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<v Speaker 1>will use to try to sell you the nitrogen usually

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<v Speaker 1>are red herrings. They'll talk about things like rust your

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<v Speaker 1>inner rims, or attacks by oxygen atoms on the inner

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<v Speaker 1>part of the rubber of the tire, all kinds of stuff.

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<v Speaker 1>Almost all of this falls into the category of urban legend.

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<v Speaker 1>But if you want to pay extra for dry night

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<v Speaker 1>virgenior tires, it certainly isn't gonna hurt anything. For more

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