Filling Your Tires With Nitrogen Gas - The Real Story

Increasingly, many tires shops are pushing nitrogen fills in place of standard air in your tires when you come to their shop. There is a lot of hype behind this and reasons given vary from less pressure loss to better gas mileage even absurd statements like, ”race cars do it, so should you.” Obviously, anything with respect to getting better gas mileage is going to sucker a substantial number of people into purchasing nitrogen for your cars’ tires. I’ll try to explain some of the true benefits of nitrogen and you can decide if it’s worth the money.

Let’s start out with some basic information about nitrogen. You should understand that 78% of the earth’s atmosphere is nitrogen already. In it’s natural form, it’s a slightly larger molecule than breathable oxygen. It’s non-reactive at normal temperatures, though like oxygen, combusts at higher temperatures. It’s a key part of our natural ecosystem and a particularly important part of how plants grow.

So, now that you know a little bit about nitrogen, what you really wanting to know is if the extra 22% is really worth it. Unless you’re getting it free, no. There are many beneficial properties to a pure nitrogen fill, but none such that you should pay for them if all you do is drive your car on the street. The first “good reason” is a reduced leak rate. Due to the larger size of nitrogen molecules, you’ll get slightly less leakage. You should be checking your tires once a month anyways, so if you were to have significant leakage in 30 days time, you probably should get your tire checked to make sure there isn’t a more serious problem.

Next, due to nitrogen’s more stable nature than oxygen, you’ll get less tire pressure variation when the tire heats up due to friction while driving. This particular property is the best reason for race cars to use nitrogen fills for their tires. On a track (or even a highway) where the tire sees a significant amount of friction, the heat generated by the asphalt-rubber interaction will cause the gas inside the tire to heat up. Because of this heat, you may see 2-3 pounds higher pressure while driving than while your car sits still in your driveway at night. Cars that race on an oval or road course could see 3-10 pounds higher pressure. So, if you partake in drivers schools or other performance automobile events, nitrogen may suit you well to keep your tire inflation consistent. For the street though, keep your tires inflated to manufacturers specifications and you will be fine.

In the end, you have to weigh the benefits vs. the cost of nitrogen fills. Will you save $50 (some shops have been known to charge this much for the fills) over the course of the nitrogen fill? No. Though it’s a novel idea, unless your car is used in special situations like high performance drivers school, just say “no thanks” next time someone tries to sell you a nitrogen fill for your tires.