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The Myth That Using Nitrogen Increases Fuel Economy

By: Scott Siegel Nitrogen as an alternative to air when filling tires seems to be gaining some popularity. The fact that Costco and other retailers are now offering nitrogen fills certainly points to nitrogen filled tires as becoming more mainstream. At almost $10 per tire does it really save fuel like it is claimed to do? Here are some answers.

Let's start with the most basic principle of all. Take a deep breath. Now let it out. You realize that the breath you took was 78% nitrogen. I'll bet you couldn't tell. Therein lies the biggest problem with the theory that nitrogen is better than air. Air is already 78% nitrogen!

A major claim made by nitrogen advocates is that nitrogen is a larger molecule and will permeate through the tire slower than oxygen. By slowing the seepage out of the tire, nitrogen will allow you to maintain the proper pressure in the tire longer.

This supposition is false. You merely need to know something about physics to realize this. The rate a gas can permeate through a porous substance depends on the mass and the size of it's molecules. Oxygen and nitrogen are literally the same size. As far as the mass or weight is concerned, nitrogen is actually lighter than oxygen. If a gas is going to escape through the tire the nitrogen would do so faster.

Applying some common logic to this can illustrate why the nitrogen supposition is false. If oxygen did escape through a tire at higher rates than nitrogen, then as the oxygen escaped, the tire would be left with mostly nitrogen. Assuming this is what happens, then over time as oxygen has been lost there might be 91% nitrogen on the residual air in the tire instead of the original 78%.

You then go to the station and top off your tires which are now filled with a high concentration of nitrogen. You add a small amount of air to the tire. Now you have much less oxygen in the tire than you did when you first inflated it. It has a much higher concentration of nitrogen.

Continuing this train of thought, if the nitrogen does continue to behave the same way, the smaller amount of oxygen now in the tire escapes from the tire and the nitrogen that remains behind becomes even more concentrated. Maybe you now have 95% nitrogen in your tires. As you continually repeat this process many times, you continue to get higher and higher concentrations of nitrogen in your tires. Eventually you will end up with only nitrogen.

The question is, if eventually you would end up with nitrogen filled tires by just repeatedly filling them with air, why would you fill them with nitrogen to begin with and spend the more money? It just doesn't make sense.

This claim of nitrogen permeating out of a tire slower than oxygen has been shown to be false just by using a little logic and common sense. There are a lot of specific laws and formulas of physics illustrating why claims of nitrogen's benefits are false. They would take many articles to explain. Really though it seems the law you are actually observing is the single most common law of behavior that is repeated over and over.

Once again there are those who are taking advantage of a situation to make a buck. Who finds an advantage to filling tires up with nitrogen? Those selling the equipment and those retailing the nitrogen. They earn more profits. Who gets the short end of the stick? That' right, it's the consumer.

Article Source: http://www.lifeweightloss.com

Scott Siegel is the author of a 143 page book of automotive industry insider secrets on saving gas and money at the pump (beatthegaspump.com). Visit us to discover how you can get better gas mileage. Find out how to increase gas mileage.
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