Somebody educate me on "Nitrogen" in the tires ?

There are actually THREE "what can/should I use to inflate my tires" answers:

Nitrogen

DRY air (with air dryer to remove moisture from air)

WET air (you know-- those coin op machines with water dripping from the air chuck)

Nitrogen and dry air both follow the Ideal Gas Law (PV=nRT). For a given temperature change, there WILL BE a given change in PSI.

Wet air is NOT an ideal gas and will give more PSI change for a given temperature change.