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Have you ever noticed the green valve caps on other people’s tires in the parking lot? I have, and I always wondered where they got them. Turns out, these people have paid to fill their vehicle’s tires with nitrogen instead of oxygen.  Nitrogen is thought to increase gas mileage, but I was skeptical about this. I did some digging and found this myth is plagued with technicalities.

Technically, proper tire inflation is what increases your car’s fuel mileage. The reason nitrogen allegedly increases your gas mileage is because it keeps your tires fuller longer. Nitrogen’s molecular design is bigger than oxygen, making it harder for this gas to escape from your tires (see diagram below). Pure nitrogen also helps to keep water vapor out of your tires, which helps to prevent corrosion of the wheel and a breakdown of the interior rubber. You will pay more for Nitrogen, which is why many people view it as a gimmick to get people to spend their money. So the question becomes, is it worth it?

Some fact checking done by BankRate.com, a free website helping people make educated economic decisions, states the damage done by water vapor in your tire is questionable due to the fact that most tire treads wear down faster than any internal damage could occur. Additionally, the website says most of the air lost from a tire comes from a leak, or the tire not properly lining up with the rim, not from it leaking through the rubber. This information left me questioning the benefits of nitrogen even more. I reminded myself to break this myth down to the basics.

The nitrogen isn’t the key to great gas mileage; maintaining proper tire inflation is. Whether you fill your tires with normal air from the gas station, or nitrogen from a dealership, if they aren’t filled properly you won’t be getting the most out of your tires. The nitrogen has been introduced to help people maintain the proper tire pressure, which helps the car run well and be more fuel-efficient. If you avidly check your tire pressure, then maybe nitrogen isn’t for you. But, if you don’t know how to check your tires, maybe nitrogen is the way to go. The choice is up to you.

Do you think nitrogen or oxygen would best suit your driving habits? Tell us in our comment section below.