Jack Williams

Do Your Tires Need Nitrogen?

Is it worth it to fill your tires with nitrogen?

The air we breathe-which is presumably what you currently use to fill your tires-is already made up of about four-fifths nitrogen. Most of the rest is oxygen. And while air is free (or, at worst, 50 cents or so from a coin operated compressor), nitrogen will cost you money. You might get a free nitrogen fill-up with your brand new tires, but refills can cost you anywhere between $5 and $30 per tire. Additionally, while pressurized air is available almost anywhere, nitrogen is usually only available at auto & tire shops.

So, why might you want to fill your tires with pure nitrogen? Adherents of the practice typically name a few primary advantages.

One is that nitrogen molecules are physically larger than oxygen molecules. Why does that matter? Over time, whichever gas you force into your pressurized tires will work its way out through the tires' rubber walls, which are porous at the molecular level. In effect, every tire has a very slow leak, and it's one you can't seal. The idea is that pure nitrogen's bulkier molecules will take longer to leak out than the mix of nitrogen and oxygen molecules found in our air.

Another advantage pure nitrogen has over air is that it's always completely dry. Water vapor doesn't exist in nitrogen. Water vapor inside your tires can cause their pressure to fluctuate, particularly in warmer temperatures.

There is also evidence that over the long term, exposure to oxygen can damage the rubber in your tires, much it damages unprotected metals through oxidization (better known as rust). Most motorists, however, will wear out their tires through normal driving before this becomes a problem. If you have a car in storage, filling its tires with nitrogen may help extend their lifespan, but controlling temperature and moisture levels are probably more important.

Our verdict? If you don't mind spending the money, filling your tires with nitrogen can't hurt. For most of us, though, air does a perfectly job. Just make sure you're checking your tire pressure regularly!

[Photo credit: Matt Richardson via Flickr, used under CC-by-2.0 license]