2017 Mazda CX-5 - why put nitrogen in my tires?

When I took my car in for an oil change and had the tires inflated, I was told I had nitrogen in the tires. The Shop put regular air in the tires and said that is ok. Why did the manufacturer put nitrogen in the tires and is it ok to mix regular air with nitrogen?

Air is 80% nitrogen. No worries at all.

The manufacturer (or the tire store) puts nitrogen in the tire for a bunch of reasons (mostly silly) and because sometimes they charge you extra for it. It is a bit of a scam, in my opinion.


It reduces pressure differential in the tires as the temperature changes. My opinion is the same as @Mustangman.

It is commonly used in high altitude aircraft tires. It will not result in anything bad or good for normal motor vehicle use.

Actually it doesn’t. Air and nitrogen expand identically with increasing temperature.

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Dyer’s wrong. Tire pressure is no more stable. Tests show that pressure loss over a year was almost the same. And day to day variations will be identical. Nitrogen’s used in race cars because of safety in a fire, and because control to 0.1 psi is important. Air compressors knock out a good amount of water (that’s why there’s a drain on the bottom of the tank), so water condensation is a minor issue. Even the actual tire guy he quotes agrees:

“Nitrogen is no substitute for proactive, regular tire care and maintenance,” says Keith Willcome, consumer tire engineering, Bridgestone Americas Tire Operations. “Bridgestone does not prefer oxygen or nitrogen—both are acceptable gases for tire inflation. Both air and nitrogen respond similarly to The Ideal Gas Law, which says temperature and pressure are directly related. For tires, this means every ten-degree change in ambient temperature will result in approximately 1 psi change in tire-inflation pressure. This change is the same for nitrogen-inflated tires and tires inflated with air. Proper inflation pressure is key to tire safety and performance.”

Over at Barry’s Tire Tech he does a good job describing while nitrogen is a waste of money:


I do live in high altitude city, so maybe that explains why nitro is in my tires. Thanks.

Nah, nothing to do with that. Airplanes us nitrogen to eliminate a fire risk, and because their tires go through huge temperature swings, so water condensation would be an issue.

That has nothing to do with it . Just keep your tires inflated at the pressure listed on your door frame plaque and find something else to worry about.

Last new tires, the green valve stem covers indicating nitrogen. It was free with the best deal on the tires I could get. Fine with me, after 50 years of driving without, whatever, but thinking in a parking lot some guy might walk by saying what a fool, paying extra for nitrogen.

Yeah hard to not put some nitrogen in them but I don’t think I’d like those green covers on my wheels anyway.

Nitrogen became a trendy, fashionable gimmick among some of the high performance junkies. It’s the same logic that puts chrome valve covers and water pumps on engines to increase the horse power.

Mazda didn’t put nitrogen in your tires, a dealer did, mostly to build their profit. I have always wondered ; does a new car prep department actually put a new car on a lift before they remove the factory air and install nitrogen; or do they leave the vehicle on the ground and deflate the brand new tire with the weight of the vehicle on it? Or do they put green valve caps on and call it a day?

Was the car bought brand new with the green valve stem caps?
Even so i t was done by dealer prep, not the manufacturer.
Besides regular air being mostly nitrogen,
the concentration of nitrogen in the tire rises over time.

I’ll take door number 3. I would expect to find a big box of green valve caps and zero nitrogen tanks at dealerships.

There appears to be a big business in selling nitrogen extractors to dealerships and shops. They don’t bring in tanks of N2, they extract it on site, it’s not 100%, but then that doesn’t matter, anyway…