Nitrogen for Tyres?
 
Briefly, here are some salient points:

- race teams started using nitrogen due to convenience; a bottle of compressed N2 at 3000psi is readily available, portable, and inexpensive. Air compressors, and/or the power to run them, may not be anywhere near as convenient for a race team that is travelling from track to track.

- it is true that pure oxygen (O2) permeates a butyl rubber membrane somewhat faster than pure nitrogen (N2).
However...
the rates we are talking about are infinitesimal in
practice. I check and adjust my tire pressure before nearly every ride, so why in the world do I care about permeation rates that are infinitesimally slow?

 		  

Secondly, regular old compressed air is actually 79% N2, while the "pure" N2 from the tyre store's membrane-separator machine is about 90% to 95% at best. It's not like we are comparing pure N2 to pure O2; the differences are fairly small to begin with.
- regarding pressure change due to temperature change: air, which is a mix of N2, O2, water vapor, and trace amounts of a variety of gases such as CO2, argon, helium, etc. has
exactly the same reaction to temperature change as pure N2.
EXACTLY the same. We can get into the Combined Gas Law and
Real vs Ideal Gases if you want elaboration here.

- heavy truck fleets that use N2 do so for one specific
reason: tire carcasses are used over and over in retreads.
O2 will degrade rubber over very long periods of time -
years. Pure N2 solves this problem and allows the carcasses
to stay in service longer. Not an issue on a motorcycle
tire.

- aircraft use N2 by FAA mandate, which is based
specifically on a concern over tire fires caused by high heat from brakes, plus hydrocarbons from rubber, plus O2 within the tyre if filled with compressed air.
See :-
http://tinyurl.com/byhyz