Everything You Need To Know About Cars
Most scuba tanks are filled with air but because corrosion is a big deal moisture is removed from the air beforehand. Why not fill tyres with dry air?
Probably cost, a fully functional scuba tank is far more important (from a safety standpoint) than a little wheel corrosion.
Moisture is also removed from breathable air because when compressed air leaves the tank, it expands causing the gas to cool. The moisture can freeze inside the regulator causing problems with air delivery.