Nitrogen a solution to lax inflation practices, says Tyre Bay Direct

Just because a tyre looks correctly inflated, it doesn’t mean it necessarily is. I was reminded of this the last time my car’s tyres were treated to a pitifully infrequent air pressure check. But at least I’m in good company when it comes to tyre pressure sloppiness. Tyre Bay Direct shares that a recent roadside survey performed by Sussex Police found 73 per cent of all inspected cars to have tyres at least 5psi above or below their recommended handbook pressure.

Along with reporting this finding from Sussex Police, Tyre Bay Direct shares the statistic that 86 per cent of vehicles involved in UK road traffic accidents have incorrect tyre pressures. This high percentage is unsurprising given the prevalence of incorrectly inflated tyres amongst the national vehicle parc, however it does raise the question of how many accidents would have been avoided had tyre pressures been correct, and what can be done to lessen the risk of under-inflation. The first of these is difficult to answer, but Tyre Bay Direct suggests that nitrogen is a simple way of keeping tyres at correct inflation levels – thereby increasing road safety and saving money into the bargain.

How does nitrogen save money and make you safer on the road?

Compressed air contains oxygen and nitrogen in roughly a 20 per cent to 80 per cent mix. It does however contain other gases, as well as water, water vapour and dirt/grease. Certain components, namely oxygen, water vapour and free water that are found in compressed air, are prone to permeation through the tyre structure. This occurs separately from any air loss that might occur due to faulty valves or leaky rims. While the wall of a tyre appears solid, it is in fact a permeable membrane that allows gases to freely pass through it. Tyre makers coat the inside of a tyre with a butyl liner to slow pressure loss, but this cannot eliminate the problem entirely.

Of the components present in compressed air, both water vapour and free water can enter the tyre in varying amounts even if identical tyres are inflated using the same gauge on the same day. Compressed air is not a specified gas and as such will always contain varying amounts of components that are not suitable for tyre inflation. In tests, the aforementioned 20 per cent oxygen to 80 per cent nitrogen mix changes to a 10 per cent to 90 per cent mix in a tyre that has aged and not been topped-up recently, demonstrating that the oxygen is exiting the tyre cavity faster than the nitrogen. So why not start with a higher nitrogen concentration to begin with? Tyre Bay Direct recommends this for the majority of us who don’t check their tyres regularly.

Inflating tyres with nitrogen produces a more stable inflation mixture that has improved pressure retention properties and ensures tyres remain fully inflated for longer. Tyre Bay Direct claims the use of nitrogen can reduce tread wear and increase tyre life by up to 25 per cent, reduce the risk of punctures by up to a third and improve fuel efficiency by two per cent.

Nitrogen has been used in tyre inflation for more than 40 years now and is regularly employed by the earthmoving industry as a means of preventing latent heat build-up and by aircraft operators in order to conform to regulations. It has also been used in Formula One, an environment where a moisture-free inflation substance is essential, for decades. Why? At tracks such as Monza, the tyre cavity can reach temperatures of 180 degrees Celsius and at this temperature water can expand to 1,000 times its original size, greatly increasing tyre pressure.

For the majority of motorists, nitrogen inflation machines provide an alternative to topping up with air every couple of weeks. Tyre Bay Direct points out that the use of nitrogen will enable the tyre to maintain the correct pressure for far longer, ensuring safer and more cost-efficient motoring.

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