Jon,, I just retired after 33 years as an IA 36 years as an A/P & 21 years as a corp pilot and Director of maint. for two airlines and one helicopter company,I have owned dozens of aircraft mostly twins. Nitrogen is used in inflatable struts & in place of pure air in air over hydraulic struts to prevent internal corrosion and freezing at altitude, even at that it happens occasionally, and when the gear freezes in the wells things get noisy very shortly after coming over the fence..
All jet aircraft today use nitrogen in the tire assemblies to help control temps. during high speed ground runs, BUT, I am NOT a proponent of using it in automotive tires.>>>Dan
Utah, I am sure you will agree the primary reason for most uses of N is because it is available and can deliver much greater pressures than shop air. If moisture is a problem (unlikely in the amounts present in typical shop air) then the use of a compressed air dryer will deliver compressed air that is drier than a popcorn fart.
The tire places that try to shove the use of N down our throats are after the money because if N was really important to have in tires they would first pull a vacuum on the tires and then fill with N.