Friday, July 31, 2009

Nitrogen Inflation

Nitrogen Inflation - Few facts:
Nitrogen has become a bit of a trendy issue — and a way to generate some extra income in certain quarters. I'm not saying there are no benefits — but they are minimal and outweighed by the cost.

Compressed air, which has worked perfectly well for more than a century, is made up of 78 per cent nitrogen, 21 per cent oxygen and a trace amount of other gases — notice that it is already almost 80 per cent nitrogen.

In some cases — most in fact — moisture in the form of water vapour is also present.

Proponents of nitrogen say it eliminates the moisture and that, because nitrogen molecules are bigger than oxygen molecules, which escape over time through the sidewall, nitrogen-filled tires will maintain their pressure longer.

Nitrogen proponents like to wave the safety flag, saying that because tires retain their pressure longer they are safer. They claim longer wear because a tire low on pressure wears prematurely.

They will now also jump on the "save fuel" bandwagon for the same reason — a properly inflated tire will help fuel mileage.

No argument from me on any of these points, but if you check your tires regularly — even once a month — you'll catch any loss of pressure and refill, for nothing.

Tire manufacturers say that while nitrogen will do no harm, they don't see any need to use it.

Consumer Reports magazine, after a year-long evaluation of 31 different all-season tires, reports that nitrogen reduced the loss in pressure an average of 1.3 psi during the 12 months in comparison with compressed air.

"All tires lost air pressure, regardless of the inflation medium, so consumers should check their tire's pressure routinely," it says.

Nitrogen is used in the aircraft industry because of the severe and instantaneous changes in temperature a tire undergoes when coming from the extreme cold at 35,000 feet to hundreds of degrees when it screeches to a stop on the runway.

Race teams use nitrogen in tires because they commonly monitor and change pressure in units of less than 0.5 psi to change handling — and replace the tires after only a few hundred kilometres, at the most.

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