There are many myths about nitrogen in tires especially when the temperatures start to dip in the fall and winter. I am sure most of you have been asked to put nitrogen in your tires from your local tire shop, which usually charges $5 per tire. In fact the first time I heard about nitrogen in tires was in aviation maintenance school. We exclusively put nitrogen in airplane tires. You might be thinking well if its good enough for aviation, why wouldn’t I do it? The reason is, because your car isn’t flying through the air. Let’s talk about this a little bit.
The regular oxygen or compressed air you would put in your tires is comprised of about 78 percent nitrogen, 21 percent oxygen and 1 percent other gases. Because of this it is not purely nitrogen and there is almost always some water vapor present. The nitrogen used to fill airplane tires or your car tires is a processed gas, which means they remove any impurities (other gasses, water vapor etc) in the regular air and fill the tank with 100% pure nitrogen. Having water vapor in the tires causes fluctuations in air pressure especially with temperature changes, therefore making it more difficult to maintain the proper tire pressure.
A common myth you have probably heard is that nitrogen filled tires will leak slower than air filled because it’s heavier. This is a very wrong statement. If you have a leak in your tire around the bead or valve stem, the tire will leak no matter what. If you do spend the big bucks on nitrogen, then make sure your tires are free from leaks and cracks so you aren’t wasting your money.
Now, I don’t want to make you think that nitrogen in tires is a ponzi scheme. Let’s get back to aviation real quick. The real reason nitrogen in tires is a good idea is because it is free from any water vapor which cause fluctuations in tire pressure. Airplanes travel at dramatically different altitudes and temperatures. They will sit on the hot summer tarmac where its 110 degrees F, and then fly to 35,000 feet where it can be -65 degrees F. This is why nitrogen makes a great case for airplanes but a not so great case for cars. Our cars simply do not go through these dramatic pressure and temperature changes so filling your daily driver car tires with nitrogen is a waste of time. You would probably spend better money buying four Starbucks coffees, two $10 scratch off tickets, or my favorite, a couple IPAs at your local bar. On top of this, most people do not have bottles of pure nitrogen laying around, so the inconvenience to only fill with nitrogen outweighs any benefits of it.
This is not to say its a complete waste though, and some racing applications, nitrogen tires would be very worth it. Racing tires also experience extreme heat fluctuations where having a pure nitrogen gas inside would benefit over regular air.
Ok, after all that you still think its best to put nitrogen in your tires. That is fine and I like your commitment! There are a few things you need to know if you go this route.
Make sure you find 100% nitrogen and your auto mechanic isn’t pulling one over on you.
Make sure to release all of the regular air in your tires before adding nitrogen. Many mechanics will just add nitrogen to your tires that have regular air, which completely defeats the purpose. Mixing nitrogen and regular air in your tires will not hurt anything, you just won’t gain the affects of nitrogen.
Stay diligent and keep adding nitrogen to your tires when they get low. If you are in a hurry and put regular air in, you again defeat the purpose and are wasting your money.
In the end be safe and most importantly keep up with your car maintenance. Check your tires once a month if you do not have a tire pressure monitoring system. Keeping up with tire pressures will not only give you better gas mileage but it will prevent premature wear on the tires. Finally, if you do have to fill your tires, make sure you do it in the morning when your tires are cool. Filling your tires after they are hot from a long drive can prevent an overinflation scenario which will decrease gas mileage and wear.
I would love to hear your stories about nitrogen vs air, so leave them in the comments below!
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