Hmmm, I went away for a day and missed all this. Just one comment to add to the good information above, noting that it is all about the moisture, not the fact that it is 78% nitrogen or 93% nitrogen.

That is the claim that nitrogen is inert, and reduces the oxidation of tires. This is true, but there is one fatal flaw in the argument. That is that tires have an inside and an outside. Let's say you stop all the oxidation on the inside. Great. Now what about all the oxidation on the outside? Are you driving in a nitrogen environment, or in air? Add in sun damage, and the outside of tires is the only issue with respect to aging of tires, the inside doesn't matter at all with respect to aging.

Similar issue with respect to flamability. Nitrogen doesn't support combustion. How many fires start inside tires? As long as there is air on the outside of tires, you can have a fire (if you have fuel, and a source of ignition).

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue