Tyres deflating too quickly

[prise]

...Bloke reckoned nitro would fix that (molecules are bigger than oxygen)....Apparently nitro is more stabile as well as runs cooler so handling is better....

Air is 78% nitrogen and 20%oxygen so if the bloke at BJ was correct then all you would have to do is wait long enough and the oxygen would escape leaving the nitrogen behind - the bloke at BJ is talking BS. It's not the oxygen that causes the problems (unless you're tyres are smoking hot) it's the water vapour or humidity in the air which causes the pressure to vary more with temperature than it would if the air was dry. That's why race teams use nitrogen, it's guaranteed to be free from water vapour because of the way it is extracted from the air and they are trying to minimise pressure rise/fall as tyres heat/cool.

Compressed air that has been dried is fine for 99% of use.