Compressed air is your tire's worst enemy. Air is about 78% nitrogen, 21% oxygen, and 1% other. Nitrogen is inert, noncombustible and non-corrosive. Oxygen, on the other hand, is immensely destructive to rubber and other tire materials. As soon as a tire is manufactured and exposed to air, the effects of "oxidation" begin to deteriorate the rubber. Over time it loses its elasticity and strength, just like an old rubber band you've probably found around your home. This same process occurs in tires inflated with air as the oxygen attacks the rubber molecules, working from the inside out, until the oxygen, and its destructive properties, permeates the tire structure and ultimately the tread.
No, the purity of nitrogen available from nitrogen generators generally ranges from 95% (low purity) to 99.9% (high purity). NitroFill generators can produce nitrogen in excess of 99.9% purity and are programmed to provide a guaranteed minimum of 95% purity in the serviced tire, which is the minimum allowable purity that must be maintained in the tire to enjoy the benefits of nitrogen inflation. Few generator manufacturers currently discuss this mandatory 95% threshold, as few are able to consistently provide the required purity to achieve it. Don't take chances with your safety.