Depends on the PSI in the tires. 60 or less, anywhere that has an air compressor. I do not like the "Feed in coins" type as they are too slow
Over 60 PSI, Truck Islands at Truck Stops. often 150-200 PSI in the line.
I carry a 150 PSI 6 gallon portable myself.. Way easier than finding high pressure air. And it does so much more than just blow up tires.. (Tires, Jacks, Wrenches, Cutter, Sander, Hammer, and more)