Further more, another question, operating temperature gives an operating pressure because warm tyres have increased pressure due to heat, hence all tyres pressures are quoted cold.
What pressures do Nitrogen suppliers recommend? Because the stock pressures will now be useless as the tyres pressure won't increase correctly because the pressure won't increase with the tyre temperature if Nitrogen is used.
Get that wrong and the tyre could be permanently under inflated... No?
This is nonsense I'm afraid Chris.
Which bit...? That Nitrogen won't expand with heat?
If so there's no point using it, fair enough.
However there is a part of that equation I believe to be useful. Rightly or wrongly. 
Exactly - nitrogen expands with increase in temperature just like any other gas.
Charles Law If it can't expand then the pressure increases.
Boyles LawThe only way it could be beneficial is if the water vapour makes the pressure increase more pronounced
Dalton's Law. If I can find some figures for the water content of compressed air I might be able to work out some answers using the Gas Laws.
I wonder how hot a tyre gets in use?