Add-On Check

Nitrogen-Filled Tires

Nitrogen may be useful in some applications, but a dealer add-on still needs a clear price and a value you actually want.

Know What You Are Paying For

What this means

Ordinary dry air is about 78% nitrogen. A higher-purity nitrogen fill does not remove the need to check tire pressure. For everyday driving, compare the dealer's charge, refill access, and claimed service with your own needs instead of treating the green valve caps as proof of value.

NASA's basic air-composition reference explains that ordinary air is about 78% nitrogen. A dealer offering a higher-purity fill should state what is included, whether future top-offs are included, and the exact separate price.

NHTSA recommends checking tires at least monthly and using the vehicle manufacturer's recommended cold tire pressure from the placard or owner's manual—not the maximum pressure molded into the tire sidewall.

Do not accept claims about fuel savings, tire life, corrosion, or pressure stability without evidence that applies to the product and your use. Even nitrogen-filled tires can lose pressure or be punctured.

What to say: “Show nitrogen as a separate line item and explain what service is included. I am declining it unless I choose it after comparing the value.”

What to do now

Check: Nitrogen add-on

Is an unwanted nitrogen charge mandatory?

Ask for itemization and decline the add-on. Walk away if the dealer will not remove or offset an unwanted charge in the written out-the-door total.

Pressure Still Matters

Check all tires cold at least monthly and before long trips, using the vehicle placard's pressure.

Separate the Charge

Green caps do not answer whether the service is optional, what it costs, or what future service is included. Get those answers in writing.

Sources & Further Reading

These sources explain general rules. Check current requirements in your state and the terms in your own paperwork.

More help with this issue

VIN Etching Review a written offer See words to say Check a written purchase quote

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Help someone understand this situation and what to check.

Rules can vary by state. Check the written offer and the linked sources. If a key term is still unclear, pause before signing.