Some where in the past there have been several cars and sets of tires. All the tires met their final end due to wear on the outside, never an issue with the internal rubber. All tires were filled with atmospheric air.
Has anyone considered "green"? A little research on the production of nitrogen will lead one to cryogenic air separation. The monthly electric bill for these production facilities are in the millions of $$, I spent a life time there. All electricity is not green or the construction/maintenance of said facility.
Then lets consider pressure. Tire and auto manufacturers take tire pressure into consideration. Bet most use air. Dig deeper into the calculations and we end up here; American Gas Association calculations. In industry where pipe line measurement are critical for payments of products, just use an AGA calc. Nitrogen is just like most other gasses, temperature/pressure compensation is required to measure how much is in a given space. The difference (pressure) between nitrogen vs air in the internal space of a tire is picking belly button lint.
Having been down this road before, I was once asked if the pressure in tires changed with the addition of weight in the vehicle. Several of the staff said "no". The test equipment was in one of my black boxes. The adapter was procured, test equipment connected to the valves on the tires and then staff members sat in said vehicle. The pressure increased as more staff members sat in the car. The load in the car will have a greater effect on tire pressure vs the gas inside the tire.
Save your money, purchase good whiskey
Stuck,