I thought the advantage with nitogren was for psi stability. Hot or cold it's the same. Am I right?
All gases follow the universal gas law PV= RT so nitrogen filled tires respond exactly the same way to temperature changes. There is a temperature/pressure affect when there is liquid water condensed in the tire and then it heats up and goes gaseous - this doesn't happen with nitrogen because water is removed completely in the process of seperating it from air by liquification.
Some say oxygen can find its way through the rubber slightly more easily so pressure may drop less over winter with nitrogen. If true, this also implies that oxygen will pass from the air outside into the tire with no oxygen so your nitrogen filled wheels may actually slightly increase in pressure over time.
More info here: http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=191
