I agree with team-gpracing. Used it because it was simpler than carrying an air compressor, and didn't require any maintenance. Didn't need to keep refilling a small air tank. Used a 5' tank, secured in the rear of the trailer. Filled it every 3-4 years for less than $15. Used it 2 or 3 times, with an impact gun, to quickly change flat tires on the truck or trailer on the interstate. I changed wheels 2-3 times per race weekend with the air gun, some weekends we were running 2 cars. The low cost of battery powered impact guns now is a good incentive to use one of them. But, I would still miss the convenience of the nitrogen tank. Used a simple pressure regulator, and commercially available N2 from the welding suppliers. Nothing fancy.
Many of the new cars require nitrogen in the tires because it is very dry. The moisture in compressed air is corrosive to the pressure sensors in the wheel. The dealers also find it a very econonical way to make a very large profit on a $15 sale. And, you look like a hero with your new green valve stem caps.
