Nitrogen tire inflation has been shown to provide a significant reduction in the total amount of oxygen that permeates through a tire over its lifetime. The result of oxygen permeation generally is considered to be oxidative degradation, or aging, of the rubber materials that make up the tire. Increased environmental temperature has been shown to increase the rate at which the oxidation reaction occurs regardless of the tire's construction. It is shown that the permeation of oxygen accelerates with temperature more slowly than the oxidation reaction itself, consistent with a diffusion-limited oxidation characteristic. This principle is used, along with the mass of oxygen flowing through tires in simulation, to predict the oxygen concentration in the rubber of the tire. The effect of nitrogen inflation gas is shown to forestall the increase of oxygen concentration through the tire for about four years. These elements provide a decision matrix for the application of nitrogen inflation in tires used in different service environments. The potential use of nitrogen tire inflation is discussed for passenger and light truck tires in routine service, for snow tires, for spare tires, and for medium radial truck tires.
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