Nitrogen is subject to the same laws for gases that air is. It does not maintain a constant pressure for changes in temperature. BTW air is 78% nitrogen and when pure nitrogen is put in a tire, there is already one ATM of air in there. To have 100% nitrogen in a tire, the tire would have to be filled in a vacuum chamber. At best, you will get about 91% nitrogen.
The only advantage to a nitrogen fill is that the nitrogen usually is dry, but there will still be some moisture in the tire from the air that is in there at the start.