Atmospheric air contains 78% Nitrogen. ):h
The only times I have seen where filling the tires with nitrogen might be of "some" help would be race cars and aircrafts.
Still even those, cannot fill their tires with 100% nitrogen unless they suck a huge vacuum to evacuate all the air inside the tire prior to filling it with Nitrogen. Unless you securely lock the beads on the wheel, it is impossible to draw much of a vacuum without breaking the bead seal.
As far as I am concerned, the whole Nitrogen bit is nothing but a big scam by tire stores to get more money from their customers. What do you do when you check your tire pressure while on the road? You add air to the tire. - There goes the Nitrogen theory out the window.
The average customer will never see a benefit by filling their tires with Nitrogen. As long as you have a way to remove moisture from the air used to inflate the tires, you won't see any real difference vs. inflating with Nitrogen.