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What is the difference between air and nitrogen in tyres?
The difference is smaller than it seems: air is already about 78% nitrogen, and the rest is mostly oxygen with small amounts of other gases and moisture.
Nitrogen inflation uses a gas with a higher percentage of nitrogen and less moisture. The two behave very similarly: both lose pressure in the cold and can escape through a hole or a leaking valve.
What advantages are claimed for nitrogen?
The main advantages claimed for nitrogen are a slightly slower loss of pressure over time and less moisture inside the tyre.
- More stable pressure: nitrogen molecules pass through rubber more slowly than oxygen molecules, so the natural drop may be a little slower.
- Less moisture: a dry gas limits condensation inside the wheel.
These effects are considered more relevant in specific fields (motorsport, aviation, some professional uses). For a car in normal use, with regular checks, the practical benefit is generally modest.
What can nitrogen not do?
Nitrogen cannot prevent punctures, leaks from the valve or from the edge of the wheel rim, nor can it replace regular pressure checks.
- It does not repair or prevent a nail in the tyre.
- It does not stop the pressure drop caused by the cold (see tyres losing pressure in the cold).
- It does not turn off the TPMS warning light if there is a real drop in pressure.
- It does not increase grip or tyre life if the pressure is not correct.
Can I top up a nitrogen-filled tyre with air?
Yes: you can top up a nitrogen-filled tyre with normal air, with no risk to the tyre. You will simply dilute the percentage of nitrogen.
Driving at the right pressure is far more important than which gas is used. If you find a tyre low and have no nitrogen to hand, inflate it with air to the value given by the manufacturer: you can find it as explained in what your tyre pressure should be.
Air or nitrogen: a quick comparison
In short, for everyday use air is perfectly fine, provided you check the pressure regularly.
| Air | Nitrogen | |
|---|---|---|
| Availability | Everywhere | Only where there is dedicated equipment |
| Natural pressure loss | Normal | Generally a little slower |
| Effect of the cold | Yes | Yes |
| Protection against punctures and leaks | No | No |
| Regular checks | Necessary | Necessary |
For your checking routine, read how and when to check tyre pressure.
Tyre going down despite the nitrogen?
If a nitrogen-filled tyre keeps going down, there is a leak, just as there would be with air: a small hole, the valve or the bead. It needs to be found and repaired, if technically possible.
In Milan and its province, SOS Tyre comes out 24/7, in 30 minutes on average, to wherever the vehicle is. Call +39 377 326 0999 for an on-the-spot repair when the damage allows.
Frequently asked questions
Does nitrogen save fuel?
Nitrogen in itself does not reduce fuel consumption. What affects it is the pressure: under-inflated tyres increase rolling resistance. If nitrogen helps you keep the pressure more stable there may be a small indirect effect, but you get the same result by regularly checking air-filled tyres.
Do nitrogen-filled tyres need checking less often?
No. Even with nitrogen, the pressure changes with temperature and can drop because of a puncture or a faulty valve. Regular checks, at least once a month and before journeys, remain necessary whatever gas is in the tyre.
How can I tell if my tyres are filled with nitrogen?
Tyre fitters who use nitrogen often fit differently coloured valve caps, frequently green, but this is not a mandatory rule. If you are not sure, ask whoever fitted the tyres. Either way, you can top up with air without any problem.
Is nitrogen needed on electric cars?
It is not a requirement. Electric cars are often heavier, and the correct pressure given by the manufacturer matters for range and wear. Whether you use air or nitrogen, what counts is checking it regularly and sticking to the value on the label.