It is well known that nitrogen gas has been used to inflate the tyres of racing cars, aircraft and heavy commercial vehicles for some time. However it is only relatively recently that it has come into popular use in normal passenger cars.
So what is nitrogen?Nitrogen is a colourless, odourless, tasteless, and non-toxic gas that forms about 78% of the Earth’s atmosphere.
The benefits claimed for using nitrogen over compressed air for inflating tyres are that it:
- Reduces the tyre’s running temperature
- Improves the ride quality
- Increases tyre life
- Keeps tyre pressures more constant
- Slows the rate of pressure loss
- Doesn’t react with the tyre and rim materials
The following is a discussion of these points.
Reduces the tyre’s running temperatureWhile there is some truth in this statement, the difference relates to the moisture content of the inflation gas rather than the use of nitrogen per se. In fact, dry compressed air will also produce a cooler running tyre. It’s also only likely to be of benefit in cases where the tyres are operating at or near their maximum load and/or speed capacities.
Reduces the tyre’s running temperatureWhile there is some truth in this statement, the difference relates to the moisture content of the inflation gas rather than the use of nitrogen per se. In fact, dry compressed air will also produce a cooler running tyre. It’s also only likely to be of benefit in cases where the tyres are operating at or near their maximum load and/or speed capacities.
Nitrogen improves ride qualityNo explanation has been offered as to why this should be the case, however there should be no significant difference in the way air and nitrogen behave at the pressures and temperatures a tyre normally operates at. The only theoretical benefit may be in terms of unsprung weight, as nitrogen is very slightly lighter than air, although the difference would be negligible and unlikely to be detectable.
Nitrogen increases tyre life
A tyre’s operating temperature plays a part in how rapidly it will wear. A reduction in temperature at high speeds and loads will be beneficial. However claims by some supporters that nitrogen will double tyre life are questionable.
A tyre’s operating temperature plays a part in how rapidly it will wear. A reduction in temperature at high speeds and loads will be beneficial. However claims by some supporters that nitrogen will double tyre life are questionable.
Reduced pressure build up
We all know that tyre pressures should only be checked when cold. The reason for this is that the pressure increases in relation to temperature. Nitrogen is claimed to provide a more stable pressure range in relation to tyre temperature. However once again the moisture content plays a bigger part than the gas itself. The greatest benefits are likely to be achieved under heavy load and/or high-speed conditions.
We all know that tyre pressures should only be checked when cold. The reason for this is that the pressure increases in relation to temperature. Nitrogen is claimed to provide a more stable pressure range in relation to tyre temperature. However once again the moisture content plays a bigger part than the gas itself. The greatest benefits are likely to be achieved under heavy load and/or high-speed conditions.
Pressure loss is slower with nitrogen than with airTyre liners and tubes are to some degree porous, and as a result air will eventually leach out. Hence the need to regularly check tyre pressures. Nitrogen, due to its chemical structure, is slower to leak out than compressed air. Therefore the pressure loss is slower. However that doesn’t mean that regular pressure checks can be neglected as there is still the possibility of a puncture or some other form of slow leak.
Nitrogen doesn’t react with the metal wheel rim or the tyre materialsProbably true. The presence of oxygen and moisture inside the tyre can cause oxidisation (rust) of the metal components. There is also a suggestion that air reacts with the rubber of the tyre itself, however it is not clear if this is detrimental or in any way reduces the life of the average car tyre. Because nitrogen is an inert gas and because it is dry, this problem is, in theory, eliminated. However, unless the tyre is evacuated (i.e. the air is removed) before the nitrogen is added, there will still be some air and possibly moisture in the tyre.
Nitrogen also has a few disadvantages that should be taken into account. These include:
- Cost
- Maintenance, and
- Availability
Summary
While using nitrogen in passenger car tyres may produce some benefits in some applications, it is questionable if the average motorist will derive any measurable benefit from its use.
While using nitrogen in passenger car tyres may produce some benefits in some applications, it is questionable if the average motorist will derive any measurable benefit from its use.
Nitrogen does not remove or reduce the need to check tyre pressures as the risk of a puncture or a slow leak is not altered.
Many of the benefits claimed of nitrogen could be achieved by using dry compressed air from a properly designed and maintained compressed air system.
Nitrogen cannot replace regular maintenance. Regardless of what inflation gas is used, maximum tyre life will only be achieved if the vehicle and tyres are properly maintained. That means regular checking of tyre pressures, wheel balance and alignment.
