Many of our clients have inquired about the use of Nitrogen, instead of air, to inflate the tires in their vehicles. For those of you with ADD, I'll cut right to the chase... No, it's not necessary. Ok, if you're bored you can stop reading now, the rest of us want to know why.
Nitrogen, an inert gas, is nothing more than dry air with the Oxygen removed. The majority of "air" already consists of Nitrogen (78% by volume). The other elements of air by volume are 21% Oxygen and 1% other gases.
The tires on your vehicle have been designed and tested to deliver their expected performance when inflated with "air" and the correct tire inflation pressure is maintained on a regular basis. Therefore, we don't recommend the use of Nitrogen to inflate tires for normal use; however, the use of Nitrogen is also not prohibited.
There are certain applications where Nitrogen inflation is advisable, i.e. in abnormal environments where wheel and tire overheating may occur such as in aircrafts, space shuttles, military vehicles, off-road trucks and race cars. In these applications, the non-flammable Nitrogen can reduce the risk of fire, because Nitrogen does not support combustion and does not add fuel to the fire.
The selling point for Nitrogen, other than its non-flammability, is the thought that it may reduce loss of inflation pressure. This is only the case when the loss is from the tire material natural permeability (diffusion through the rubber). Most inflation loss occurs where the wheel and the tire meet, from the valve and also from the valve/wheel interface.
The most important thing is just to maintain the correct tire inflation pressure on a regular basis as recommended in your Owner's Manual. Under inflated tires can reduce road holding, increase hydroplaning risk, increase road hazards sensitivity, reduce tire life, increase fuel consumption, etc.
So... unless you're going to fly it, launch it into space, race it, put out a fire with it, or take it off road, your vehicle is just fine with good old-fashioned air.