Nitrogen in Tires: Does Nitrogen Improve Gas Mileage?

Nitrogen in tires is touted as a way to increase your MPG.

Since it costs about 30 bucks to fill your tires with Nitrogen, it would be a reasonably priced modification if it worked.

Will filling your tires with nitrogen help you improve your gas mileage?

What Do Nitrogen in Tires Advocates Say?

We looked at a web site advocating the use of nitrogen in tires as a means to:

• improve gas mileage
• increase pressure retention
• increase tire life

On this site, GetNitrogen.org, they claimed that, when using regular air, your tires will lose 1-2 psi per month. However, with using nitrogen in tires, you will lose 1-2 psi every 6 months.

Why does this matter? According to this site, maintaining proper psi in your tires is essential for good gas mileage. And they are 100% correct. However, does that mean that you need nitrogen in your tires to accomplish this?

So, let's have fun with Math!!:

Regular air is comprised of the following gases:

• 78% Nitrogen (N2)
• 21% Oxygen (O2)
• 1% Water Vapor & Other Gases (OG)

Using regular air in your tires, nitrogen in tires advocates claim that oxygen escapes from your tires at a faster rate (approx. 3-4 times faster) than nitrogen. Therefore, filling your tires with nitrogen will maintain tire pressure for a longer period of time, requiring fewer fill-ups and maintaining better MPG.

More Mathematics - I know... Fun, right?

Let's say that your owner's manual states that 32 psi in your vehicle's tires is ideal for safety, better handling, and reduced wear on your tires.

With the statistics listed above (ratio of N2, O2, and OG), the break down of your psi would be as follows:

N2 = 24.96 psi = 78%
O2 = 6.72 = 21%
OG = .32 = 1%

*Note: Nitrogen in tires advocates mentioned that "other gases" escape at an even faster rate than oxygen...about 250 times faster than nitrogen

If you lose 1.5 psi per month, this is what that would look like:

1.18 psi O2 lost +.32 psi OG lost =1.5 psi

What's left in your tire? The psi amount of nitrogen doesn't change, as oxygen and other gases escape faster.

You must now put more air into your tire, increasing the tire pressure to 32 psi. You lost 1.5 psi, so you must add 1.5 psi.

That 1.5 psi is broken down the same as any other amount of air with regard to percentage. So that 1.5 psi is still 78% Nitrogen, 21% Oxygen, and 1% Other Gases.

Do you see where we're going with this?

78% of 1.5 psi = 1.17 psi N2
21% of 1.5 psi = .315 psi O2
01% of 1.5 psi = .015 psi OG

Aha! So now we see that with every fill-up, the amount of oxygen and other gases in our ratio gradually decreases as the nitrogen levels increase!

N2 = 26.13 psi = 81.67%
O2 = 5.855 psi = 18.3%
OG = .015 psi = .0005%

See the difference? We went from a ratio of 78% N2 to 81.67%. With each fill-up of air, you increase the levels of nitrogen in tires!

After about 3-4 months of filling up once each month, you'll have around 92.5% nitrogen in your tires, close to the same levels that nitrogen in tires advocates consider optimal. And you would have done it for free!

Should You Use Nitrogen in Tires?

Don't waste your money putting nitrogen in tires to improve gas mileage. As long as you are vigilant and checking tire pressure once per month, you will maintain the optimum pressure for better gas mileage and other benefits, such as increasing the life of your tires.

Once you have your nitrogen levels up, the theory nitrogen in tires advocates claim is that you won't have to fill-up as often. That's merely a convenience. It does not save you money or gas. It just ensures that you don't have to air up your tires for several months as opposed to every month.

However, if you're one of those people who always forgets to air up your tires or check your pressure on a monthly basis, by all means, go and pay the $30.00 to fill your tires with nitrogen. But make sure you aren't fooling yourself into thinking that the nitrogen is saving your gas. It's the tire pressure that saves gas.

Once you get the nitrogen in your tires, you will note a slight increase in your MPG. This isn't the nitrogen in your tires causing this, but the optimum tire pressure. Maintaining good tire pressure will save gas in your car, whether you use air or nitrogen.

What About the Other Claims About
Nitrogen Increasing Tire Life?

This is pure bologna. Nitrogen in tires advocates state that oxygen in your tires eats away at the inside, reducing the life of the tire. In reality, this is a very long process and you're likely to be running on bald tires well before the air inside the tires has any affect on the integrity of the tire rubber.

But the FAA and NASCAR Use Nitrogen in Tires!

The FAA requires all planes to use nitrogen in their tires instead of air, but that's because at high altitudes, pressure changes with oxygen more than nitrogen. This is a safety measure to prevent air from expanding and contracting too much, which will cause a blowout.

NASCAR is also a special circumstance, as the guys in the pits need to be able to regulate air pressure much more closely. In addition to that, the amount of use on the tires in NASCAR greatly increases wear and safety hazards. Using nitrogen in these unusual circumstances is a safety issue. Unless you're driving your car at racing speeds constantly, NASCAR's use of nitrogen does not apply to you.

The Bottom Line...

Check and maintain your tire pressure to improve gas mileage in your car, reduce wear on the tires, and extend the life of said tires.

If you don't know how to do this, it's really quite simple.

First, purchase a tire gauge. Digital tire gauges are the simplest way to go and are very affordable.

Then, watch this video for simple instructions on how to check and fill up your tires.

Another important maintenance tip is to rotate tires on your vehicle to improve gas mileage. This helps to evenly distribute the wear on your tires, extending their life and improving fuel economy. See your auto mechanic to do this, or ask the guys that do your oil changes if they'll do it for you.

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