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As the question says, does filling pure nitrogen has any significant advantages, given the fact that normal air is ~80% nitrogen?

Thanks for your time.

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the advantage is for the people installing the nitrogen,they can charge you more. –  mikes Mar 15 '12 at 19:55
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2 Answers

up vote 10 down vote accepted

It's always been my understanding that it eliminates the water vapor making the heat have less and more predictable effect on tire pressure.

Unless you are driving a race car or an airplane I don't think it's worth the trouble IMO

I found some more information I have listed and sourced below

It's not about the nitrogen. It's about reducing oxygen, water vapor and other gases.

By reducing the percentage of oxygen, water vapor and other gases in your tires from 22% to 7% or lower, your tires will maintain proper pressure longer than if you use “plain old air.” For example, with 95% nitrogen in your tires, they retain optimal pressure three to four times longer.

Source

Fundamentally; air, oxygen and nitrogen will all behave exactly the same in terms of pressure change for each 10 degrees of temperature change. However temperature alone is not the whole story.

Ambient air contains moisture, nitrogen does not. If moisture is present it contributes to a greater change in pressure simply because at lower temperatures water condenses to become a liquid. The liquid form of water occupies very little volume and contributes only a negligible pressure to the tire. But at higher temperatures, such as those in a running tire, water evaporates inside the tire and becomes a gas which increases pressure in the tire.

Ambient air contains about 21% oxygen. Oxygen’s smaller molecular size allows it to permeate through the rubber of the tire. By inflating with nitrogen, which is much less permeable than oxygen, the pressure changes due to oxygen loss are greatly reduced.

The racing industry is correct; nitrogen is more predictable. Because nitrogen is dry it has no moisture to contribute extra pressure changes with temperature. Because nitrogen permeates out much slower than oxygen pressure changes due to that leakage are almost eliminated compared with ambient air.

Let’s get a little deeper into the science. Keep in mind that the air in your tires changes about 1psi for every 10 degree temperature change. This means that a significant change in temperature will create a significant change in your tire pressure. Here is a set of Ideal Gas Law calculations showing the effects of a 10F degree temperature change on truck and passenger tires. The two sets of data represent different initial temperatures of 60F and 90F. This demonstrates that the magnitude of the pressure fluctuation differs depending on initial conditions but only slightly.

Source

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Thanks for your answer –  Gowtham Mar 16 '12 at 13:57
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As a side note, few of the amateur racers that I know bother with nitrogen. Mostly because during racing events you can be changing your tire pressures all day long. If nitrogen's readily available at no extra charge, sure, fill 'er up. However, if it costs extra or is a hassle, don't bother. –  Brian Knoblauch Mar 16 '12 at 14:57
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air leaks through rubber over time. nitrogen is much less likely to leak. while properly inflated tires can improve your gas mileage, making sure you tire pressures are ok is much more economical than buying nitrogen.

its also doubtful that you are getting pure (or even close to pure) nitrogen either.

http://www.popularmechanics.com/cars/how-to/repair-questions/4302788

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