Flat tyres

[willowman]

Something that has always puzzled me. Car tyres always seem to go flat quicker when a car is left standing than when it is used regularly. Does this actually happen or is it my imagination?

[KebabMeister]

I guess it does happen to a small degree but I suspect it would be neglible.  When you drive your car the air in the time becomes hot and expands and the tyre pressure goes up.  It only goes back to the 'normal' tyre pressure when cold.  When new cars are delivered to garages they usually have around 50 - 65 psi in the tyres rather than, say, 30 psi.  Anyway, always check/adjust your tyre pressure when the tyre is cold, not hot!  You'll get an incorrect reading!