I kinda think nitrogen is bogus. If someone would fill ya for free, I'd take it, but wouldn't pay for it.
I have it in my cage, haven't noticed a difference in my Hyundai.
Room air is 78% nitrogen. So does increasing the concentration 22% do any good? I really don't think so.
But N2 is bigger than O2 (21% room air) right? A nitrogen atom is 65 picometers. An oxygen atom is 60 picometers. Stick them together in their diatomic natural state and you get a nitrogen molecule approx 130 pico in diameter and an oxygen molecule about 120 pico in diameter. So the question is whether that 10 picos make a difference in air escaping from a tire? I just don't know if anything in a tire is exacting to 10 pico to make it worthwhile.