All tires fail due to interior oxidative deterioration, structural defects from manufacturing errors, improper tire design, road hazards, and exterior cracking caused by ozone and ordinary oxidation, most important being interior oxidative deterioration. This failure cause, while being most important, is least understood and appreciated. Oxidative deterioration of tires starts within the interior gas chamber, which acts triply for ride cushioning, as the reservoir of heat generated by the running tire, and as the vessel which contains oxygen to effect the tire's destruction. Arrhenius' law and the mass action law of chemical reactions are followed in that oxidative deterioration is governed by heat (temperature) and oxygen concentration. Since hysteresis (running temperature) can only be controlled within limits, lowering the oxygen concentration of the inflating gas is the only remaining way of inhibiting oxidative deterioration of tires, which is a cumulative effect of time, temperature and interior oxygen concentration. Five carefully controlled passenger and truck tire tests were run during the past eighteen months to investigate oxidation phenomena. In each test, one half the test sample was inflated with ordinary air, the other half with an inert gas to reduce the oxygen concentration. Over 2.5 million tire miles were run in these five tests. A sixth test involving over eighty truck tires was run more than 6.5 million tire miles during the past 36 months to observe the oxidative effect of air inflation upon inner tubes and tire body deterioration. All six tests show strikingly that oxygen-free inflation gas has a profound and major beneficial effect upon overall tire endurance and upon tire wear. Actual performance data show tire endurance of passenger tires to be improved an average of 22 per cent when oxygen concentration is reduced to 0.6 per cent and wear improvement of 15 per cent at a point where tires were only 64 per cent worn.