Motoring Weekly

For many years there has been a push by some tyre dealers to sell nitrogen filled tyres and the premise is because so do some racing cars and aircraft. I though I would look at the reasons why and the claims of using nitrogen in the tyres.

There are several claims being put forward for the use of nitrogen:

● Nitrogen doesn’t leak therefore providing a consistent pressure.

● Nitrogen doesn’t corrode alloy wheels.

● Nitrogen doesn’t eat away the rubber.

And tyre dealers add to this:

● Improved tyre life.

● Reduced fuel consumption.

● Improved road holding.

So, what’s the truth? Well air is made up of 80% nitrogen and so when you fill tyres with nitrogen you are removing the impurities and oxygen. Aircraft and racing cars use nitrogen because they provide a more consistent pressure when heat or cold cycles can cause problems. Take for instance a pilot who doesn’t want a tyre to go from freezing to very hot and explode, which could happen if the tyre is filled with air.

This really doesn’t apply to cars – there is no immediate heat change as cars are not decelerating from several hundred km/h to a stop, and road cars do not consistently lap a super smooth circuit at 250 – 300 km/h for an hour at a time. Road tyres are designed to withstand the pressures of rougher surfaces.

It is worth noting also that race tyres and road tyres – even aircraft tyres are designed and built differently with different lengths of life.

So, tyre dealers remove your tyres, clean out the carcass and then fill it with nitrogen. This means work effort that can be charged for. Many dealers then offer free top ups. But why? If it doesn’t leak, why would you need a top up? Incidentally, nitrogen does leak out of an aircraft tyre – it’s designed to do that for safety purposes!

The next claim is that nitrogen doesn’t eat away alloy wheels. Have you ever known a car owner to replace his alloys because they’ve disintegrated? I haven’t – I have known other damage to cause replacement though, mainly rim damage from poor roads or tyre dealers throwing the wheels around but not because the air in the tyre has destroyed it.

And then there is the claim that air eats away the rubber from the inside of the tyre. This way well be true, however, you will replace the tyre a long time before it becomes a problem. Car tyres have a very short life compared to the time it takes for the rubber to break down. Seriously, you’re going to replace a tyre within three years of having it fitted especially if you’re an enthusiast and look after your car. If you drive at reasonable speeds, then the tyre will change as it runs through multiple heat cycles and will need replacing to give you optimal grip.

The tyre dealers put up their claims in an attempt to make you part with your money. The three I described earlier of increased tyre life, better fuel economy and better road holding all apply to properly inflated tyres – even filled with good old air. These are not specific to nitrogen filled tyres.