Originally posted by DemonSVT:
Actually all military aircraft tires are filled with nitrogen.
It's because it does not have any water vapor (moisture) in it and resists compressing and contracting due to heat cycling. (stable pressure)
I've filled many of tires... 
military and civilian aircraft alike all use nitrogen in all areas where is gas is used, wether its in tires, shock struts or accumulators. Its used for exactly the reasons you say, its dry, and is stable at high pressures and temperatures, plus its an inert gas so it won't react with other metals, seals, or fluids used in aircraft systems.
