In the aviation industry, we use dry nitrogen for tires as well as for precharging gas strut units.  Two fold reason.  In struts, we want dry air, since any moisture can both freeze and/or cause corrosion.  In tires, using nitrogen in thought to prolong the life of rubber, which reacts to oxygen.  When you consider that in a light aircraft it is not unusal for tires to be on for quite some time, this makes sense. It's bad enough that dry rot occurs from the outside, but we don't want it to come from the inside as well.

> Date:    Wed, 23 Apr 2003 19:01:04 -0700
> From:    Steve W <croatoa@YAHOO.COM>
> Subject: Fwd: Re: Tyres and nitrogen
>
> VW Folks,
> If normal air is used in a tire and the N leaks
> out much slower the mixture in all of our tires
> would become a higher and higher concentration of
> N over time as it is refilled and the other stuff
> leaks out.  Just a though.
> Steve