Nitrogen filled tyres?

I was behind a truck yesterday with a sign on it that the tyres are filled with Nitrogen. Somebody also told me that he use this on his car - handles better. Can this have an effect? Logic tells me that the tyre would not know what gas is in it. Is this another yuppie fad or do different gasses behave different under these conditions?

I know someone in the tyre business and asked him the same question.

I don’t know the science behind it, but I do know that a lot trucks and some private motorists use nitrogen in their tyres. The tyres last longer, are kept cooler, encourage fuel consumption, and there are fewer tyre failures with nitrogen filled tyres.

Sounds fishy to me. How can the outside of the tyre behave different on account of what is inside?

OK, followed the link now. Still sounds fishy. Maybe in a truck - higher pressure. But a normal car? Car companies would have put the cars on the marked like this if it was better.

I did a quick search - nitrogen is used in F1 cars and in other motor sports, as well as in aircraft tyres. The main reason being that it’s an inert gas and in the event of a fire it doesn’t add to the problem, like a normal air filled tyre would. And…

Most importantly, by using it to reduce the concentration of oxygen in a tyre it possible to equalise the partial pressure between the air inside each tyre and the surrounding atmosphere.

As a result, the common problem of slow deflation caused by oxygen slowly leaking through the tyre wall is virtually eliminated, thereby ensuring that tyres remain at their correct pressures between vehicle servicing.

This has the added benefits of improving fuel consumption and of enhancing safety by minimising the danger of under inflation.

I think the reason that we in S.A. don’t use it as much as they do in Europe is because there aren’t enough depots for us to fill our tyres with nitrogen. I know there was a depot in Benrose, Johannesburg, I’m not sure if it’s still there. Transport comapnies have their own private depots because nitrogen isn’t readily availble anywhere else.

Hope that helps :wink:

Most SA tyre fitment outlets, e.g. Tiger Wheel & Tyre and similar, these days offer customers the option of nitrogen fills at around R10.00 per tyre. Thereafter, any topping up is free of charge. They usually have a top-up bay at the front of the outlet. Dr 'Luthon64 asked a race pit technician about this, and the short answer is that it’s not really justifiable for normal passenger cars.

There’s another reason that nitrogen has advantages over air in tyres, but this only really comes into play in high-stress environments such as aeroplane landings, large lorries, F1 and rally cars. The nitrogen molecule is slightly smaller both in mass and in cross-section than the oxygen molecule, so pure nitrogen’s behaviour is closer to that of an ideal gas (p×V/T = constant) than air, which contains near enough 20% oxygen. The result is that the tyre’s response to deformation in high-stress situations is slightly more linear, giving a marginal improvement in response and road holding.

The most important factors, however, are the fire risk and pressure maintenance issues.


More on this here.


The air we breath (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.

Most importantly, by using it to reduce the concentration of oxygen in a tyre it possible to equalise the partial pressure between the air inside each tyre and the surrounding atmosphere.

I can’t make sense of this bit.