Several benefits exist to using nitrogen in tires. Nitrogen, unlike common compressed air, does not contain any water. Water can cause rust to form in a vehicle's wheels, and this can lead to leaking air around the wheel's bead. Another benefit in using nitrogen in tires is that the molecular make-up of nitrogen is larger than air, thereby slowing the rate of the gas leaking through the rubber. Reduced weight, lack of fire danger as well as less variation of tire pressure due to temperature fluctuations are all benefits of using nitrogen in tires.
Commercial airlines as well as the United States space shuttle program use nitrogen in tires to prevent fires and blow-outs caused by over-heating tires when landing. When an airliner touches down, the tires are subjected to great amounts of heat as the brakes attempt to slow the heavy plane to a stop. Tires filled with compressed air are in danger of overheating and causing a blow-out. Placing nitrogen in tires prevents this from occurring. Using nitrogen in the tires also protects against flat tires from the cycling of cold and hot as the plane goes from the runway to cruising altitudes and back.
Competitive racing teams use nitrogen in tires for many reasons. The reduction in weight of a nitrogen-filled tire is minimal when compared to that of a compressed air-filled tire. Often in competition, a minor reduction in weight can be the difference in victory or the loss of a race. Teams also put nitrogen in tires to hinder the difference in tire pressure increase as the tire comes up to racing temperature. A tire filled with compressed air can vary greatly from the initial air pressure to the air pressure as the tire gets hot, causing the race car to become difficult to drive as the handling characteristics go awry.
On a street-driven vehicle, the benefit of running nitrogen-filled tires is found in fuel mileage. The nitrogen allows the tires to maintain an optimal tire pressure over a greater period of time. It is a fact that fuel mileage is increased by maintaining tire pressures; however, many people do not monitor tire pressure on a consistent basis. Considering that compressed air can contain as much as 5-percent water, maintaining proper tire pressures can be achieved easily by running nitrogen in tires rather than compressed air.