Good Question: Does Nitrogen Help Fuel Efficiency?

MINNEAPOLIS (WCCO) — With skyrocketing gas prices, some say carpooling and biking may not be the only ways to lessen the pain of paying at the pump. They recommend nitrogen in tires.

Debbie from Forest Lake e-mailed us to ask: Does filling our tires with nitrogen improve fuel efficiency? Good Question.

“It’s becoming more frequent,” said Costco manager and former Tire Center employee Chuck Henning. “Most places it’s common now.”

Costco was one of the first companies on the nitrogen bandwagon, offering free nitrogen fill-ups with the purchase of tires.

“The benefit of nitrogen is the consistent pressure, whereas if you’re rolling on an under-inflated tire, it creates more rolling resistance, thus leading to a lower gas mileage,” Henning said.

Henning says nitrogen helps to keep the PSI (pounds per square inch) more constant in the event of a temperature change.

“For every ten degrees that the air temperature changes, you would lose one pound of air pressure,” Henning said. He argues with nitrogen, the PSI is constant.

We went to the Physics Department at Hamline University in St. Paul, where longtime professor Jerry Artz sees things differently.

Artz says the atmosphere is already 78 percent nitrogen to begin with and the rest is mostly oxygen. The oxygen that’s in the air, which we fill our tires with, is actually helpful, he says.

Oxygen has a higher molecular mass than nitrogen. Artz says this is important because more massive molecules mean slower movement — thus it won’t diffuse through the tire’s cracks as quickly.

In other words, he says, the dry air is going to stay in the tires longer than a nitrogen concentrate. Artz also says both oxygen and nitrogen react the same to temperature changes.

The one benefit to nitrogen, and the reason you see nitrogen used in airplanes and race cars, is because there’s less water vapor. The more water vapor, the more corrosion on metal surfaces.

One thing’s for certain: the best thing you can do for your tires is to check the inflation pressure once a month.

  • Sharon Anderson

    I know nothing about the science involved but I do know that my tire pressure has remained constant for the last 2 years since I had nitrogen put in the tires. My car has a sensor that indicates low pressure and it would alarm whenever the weather changed. I had nitrogen put in my tires and I have had no problem since. I don’t know what that does for my gas mileage but it sure saves on trips to the gas station to put in air.

    • former tire tech

      Yeah, well I have air in my tires and have not needed to put air in them for over two years. All you need is a clean rim (good tire places should clean off the corrosion, especially on aluminum rims) and a good tire mounting. Nitrogen makes no difference, besides those ugly green caps they throw on your valve stems.

      • jimmy


        • former tire tech

          never laid off. its called being smart and getting a better job moron

        • dev

          jimmy = never held a job.

  • Duuuuuur

    It is nothing but snake oil.

  • gregladen

    The use of Nitrogen in racing car tires is not due to corrosion, according to my vigilant blog readers. It is because of greater variation in water vapor under changes in heat.

    Details here:

    Bottom line for your personal car? Go ahead and use the Nitrogen, and check your air pressure every week faithfully. Also, drain your hot water tank annually and check with your physician before changing your exercise routine!

  • dev

    Jerry Artz has it backwards and should probably have his credentials scrutinized. Lots of fraud in acedemiics

    • Exp

      @dev: Yet you provide no information to how it’s backwards. I question whether you know anything yourself and are just looking to contradict someone in a trolling attempt.
      More massive objects need more energy to make them move faster. That’s basic physics, something I’m assuming you never took in school. If an atom is heavier, it takes more energy to make it move faster, meaning it’s MORE resistant to changes in temperature.
      I would like to hear if they use additional bead sealer with the pure nitrogen to prevent the smaller atoms from leaking out faster (just like helium does out of a balloon). That sealer would be the reason the tires don’t leak as often as regular ones.

      • Real Talk

        Take it all with a grain of salt…both sides.

        First off…this is ONE professor…from HAMLIME non the less. Its not like a group of facilty at MIT conducted through experiments to prove or disprove the nitrogen hypothesis in the REAL WORLD.

  • March Roundup of Nitrogen Tire Inflation News

    […] Does Nitrogen Help Fuel Efficiency? – CBS Local […]

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