Nitrogen in Tires: Hot Air or a Cool Breeze?

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Recently, you may have seen articles or news reports about the advantages of replacing the air in your tires with pure nitrogen. Claims range from improved handling and pressure stability to gas mileage and tire life. Is there really any advantage to having pure nitrogen in your tires, especially given the price per tire for this service?

The air that you normally put into your tires is 78 percent nitrogen already, with the rest being mostly oxygen (21 percent) and other various gases (that remaining 1 percent).

Pure nitrogen is just that - 100 percent nitrogen gas with no other gases present. Many car dealers and other locations offer nitrogen fill ups, with more locations appearing every day. It's estimated by getnitrogen.org that there are over 11,000 dealers in the United States as of October 8, 2008.

Some people claim that they do get much improved handling with nitrogen in their tires, while others don't notice any difference. Much of this may come down to the road condition and the kind of vehicle driven, but it may also be a personal preference for tire pressure too. Regardless, driving your car with the tires at the manufacturer's recommended pressure will improve your gas mileage over time, and reduce tire wear, saving you money.

One of the main advantages of having pure nitrogen in your tires instead of plain old air is the lack of water vapor present. Ordinary air can have a lot of moisture in it, and as the temperature changes, this water vapor can condense and reform. This can and does change your tire pressure, as it forces the air inside your tires to expand and contract. Over a long period this not only changes the pressure, it can cause wear and tear on your tires. That said, it's fairly minor, and the difference between pure nitrogen and air won't make a significant difference to your finances or driving efficiency, other than to cost you money for the nitrogen tire fill in the first place.

The oxygen present in air causes oxidation inside your tires, responsible for rust and degradation of rubber. Pure nitrogen doesn't. Again, it's such a small amount of wear over a long period of time (on a part of your car that will need to be replaced after a certain length of time anyway) that it doesn't really make a big difference, especially if you're being charged for your nitrogen top-ups. Giving that small amounts of oil and water may get into your tires when you use standard air supplies provided at gas stations (professionals probably keep their equipment in better condition) it's unlikely your tires will see any real advantage from nitrogen over air.

Consumer Reports ran a yearlong study on the subject, and concluded that any slight improvement gained by filling tires with pure nitrogen was not a replacement for regularly checking for proper inflation, regardless of what's in your tires. If you can get your tires filled with nitrogen for free (as part of a deal with new tires, for example) it's probably not a bad idea - the advantages are minor, but a free advantage is always a good one. Otherwise just keep checking your tire pressure regularly and keep them topped up with ordinary air (which, remember, is already 78 percent nitrogen) instead.

What do you think about putting nitrogen in tires? Let us know!