I used to drive a car that the tyres filled with nitrogen. I find it fuel saver than air. Nitrogen dealer is limited, only can be found at some workshops eg Sg Buluh and Petronas gas station. Aeroplane and F1 used nitrogen. Guess, I'm going to fill my tyres with nitrogen, its lighter. Before that, need to check out more details the pro n con. Yawning...goodnight!