So why is nitrogen used? In its pure form, nitrogen has been used primarily because it doesn’t support moisture or combustion. Nitrogen is an inert (non-flammable) gas – basically, nothing more than dry air with oxygen removed. In fact, ambient air contains about 78% nitrogen, 21% oxygen and 1% miscellaneous gas. Because of nitrogen’s inert properties, it is often used in highly specialized tire service applications and/or demanding environments. These tire service applications usually include aircraft, mining, and commercial/heavy use. Also, nitrogen is used in professional auto racing where extreme vehicle speeds are involved. Dry nitrogen is used in this regard to help reduce tire pressure variations where even small differences in pressure can affect vehicle handling at the extreme limits of performance.