You might be aware that purified nitrogen has been used to inflate tyres on aircraft and racing cars for many years but does it really make sense for ordinary car and van tyres?

The air we breathe (and the normal compressed air used to inflate tyres) contains 78% Nitrogen, 21% Oxygen and 1% other gases but some tyre specialists are now offering – at a premium – to inflate tyres with pure nitrogen.

Nitrogen for aircraft and F1 tyres

Planes fly at heights where temperatures may be as low as -40C. Moisture in the tyres can freeze causing vibration and balance problems when landing. Pure nitrogen is dry so eliminates this problem. Using dried compressed air could achieve the same thing.

In motor sport, the elimination of moisture in tyres through the use of pure nitrogen (or dried compressed air) can help reduce tyre temperature when operating in extreme conditions, close to maximum load/speed.

Nitrogen in car tyres

For passenger car tyres the main claims seem to be:

• Less corrosion – because unlike air there’s no moisture in pure nitrogen
• Slower rate of pressure loss – nitrogen molecules are larger than oxygen molecules (which make up 21% of compressed air)

Air loss can occur through the inner liner of the tyre as well through the valve, punctures, or failure of the seal between tyre and wheel rim. Pure nitrogen might leak more slowly through the liner, but you would still have to check tyre condition and pressure regularly.

Corrosion of the tyre from using normal compressed air is unlikely anyway because only the outer tread band of a car tyre contains steel – the amount of moisture reaching it from the inside is minimal.

To change to nitrogen you have to have the air already in the tyres removed before the tyres are re-inflated with purified compressed nitrogen. There will be a one-off charge per tyre but once filled with nitrogen, future top-ups would have to be with nitrogen if any advantages are to be maintained.

Overall, while accepting the possibility of purified nitrogen being of benefit in certain applications, we don’t think that the cost and possible inconvenience are justified for normal passenger car use.