tyre inflation - why use nitrogen?

for many years nitrogen has been used to inflate tyres fitted to trucks, racing cars and plant vehicles used on building sites and mines. recently, some tyre fitters have begun to offer nitrogen tyre inflation for owners of cars and light commercial vehicles but what are the advantages of using nitrogen gas to inflate your vehicle's tyres over ordinary compressed air?

Well, for a start, all tyres over time will suffer pressure loss as the rubber used to make inner tubes and liners used in tubeless tyres is not completely impervious to leakage. That's the reason why it's necessary to regularly check your tyre pressures. Due to the molecular structure of nitrogen gas, it bleeds through the inner liner or tube at a much slower rate than normal compressed air. Of course, it's still important to carry out regular pressure checks because it's possible that a certain amount of leakage may occur through valve leaks or slow punctures. But the use of nitrogen will help to keep tyre pressures constant. Police forces have carried out roadside surveys on tyre pressures and on average they've found that 75% of those tyres checked had incorrect pressures. What's more road traffic accident statistics have shown that 86% of those vehicles involved in crashes have tyres inflated to the wrong pressure as against those set by the manufacturer.

Another advantage of nitrogen over compressed air is that tyres will run at cooler temperatures which results in increased tread life of up to 25% increase. The amount of increased tread life depends on how much that running temperatures are reduced and the use of nitrogen helps in this respect. A tyre running along the road surface produces friction and therefore heat. The heat produced by this friction will produce a considerable amount of pressure build-up, but with nitrogen, there's less pressure build-up due to heating. Excessive heat can lead to tyre failure and this one of the main reasons why nitrogen is used so much in circuit racing. In every day motoring, drivers could see reduced average fuel consumption of up to 5% and gain better road holding too.

Using nitrogen rather than the usual compressed air helps to reduce another problem area, the oxidisation, or, if you prefer, rusting of steel wheels, a common problem on trucks and vehicles used in mining. Rusting occurs when water and oxygen are present and in theory at least, nitrogen inflation should prevent the oxidisation of rims as there's no water vapour or oxygen present.

There are however, a few disadvantages of using nitrogen rather than the usual compressed air to inflate your tyres. Firstly, it is considerably more expensive and the cost effectiveness of nitrogen inflation does very much depend on the specific application. Secondly, adding even the smallest amount of compressed air to a tyre that's inflated with nitrogen during the pressure top-up will negate the advantages of nitrogen inflation. Lastly, not every service station or tyre fitter offers the option of nitrogen although it is slowly becoming more commonplace. Recently, machines have become available that can dispense nitrogen gas for tyre inflation and this should help to bring down the cost for everyday road users in cars, light vans and trucks. Perhaps, nitrogen tyre inflation will become the norm over the next few years. It's an option that certainly seems to makes sense.

To sum up, the main advantages of inflating your vehicle's tyres with nitrogen rather than compressed air are:

Up to 25% longer tread life

Better road holding

Possible 5% reduction in average fuel consumption

No or reduced corrosion to the inside of the wheel