Why nitrogen?

It all sounds like BS to me- if it's the tire we're discussing, there's no
contact with the nitrogen, just the inner tube. The outer surface of the
tire is in air of course, along with exposure to UV light, salts, etc. The
tire is going to lose its rubber well before it starts to oxidize and crack.

A tube perhaps might be more subject to oxidation, but it's dark in there,
not a lot of UV to make stuff that cause oxidation like free radicals and
ozone, and the increase in the partial pressure of oxygen at 200psi is only
around 15fold, or from around 140mm Hg to around 2000mm. If it'sdry air, I
can't believe it would make that much difference.

Need to see the aging data on rubber kept in air versus nitrogen.

Just realized I was starting to sound like you know who, so will stop this
and have another cocktail.