How I love the air compressor topics. Everyone has their opinion and you probably won't see two alike responses in a hundred.
rvten, I carry a Sears Craftsman AirBoss 115 volt, 135psi compressor. If needed on the road away from shore power, I simply start the genny and plug in and go. It's small and compact, very quiet, and will air my class c tires up just like a big compressor. For an rv needing 70, 80 or so psi, the 12 volt models aren't worth the space they take up. Great for a 32 psi car, but for 80 psi rv tire, nope. Thrie a bit pricey, now running about $160, but they go on sale all the time for $99 to $115.
If you have a genny, 115 volt is the only way to go. If your on some back road area, and need air, I don't think a gas station will have a long enopugh hose.
Grumpy