I'd get a little pancake compressor from Home Depot. The Porter Cable and DeWalt compressors are nice. They'll set you back a couple of hundred. They're not 12V but they're light enough to throw in the bed of the truck or trunk (not to carry arund, just to take somewhere if you needed to). If you want a 12V to carry in the car, there are alot of them out there and I'm not familiar with them.

Generally speaking, if you have to air up a tire on the side of the road, the tire went flat fast. In that case, the 12V aint gonna help. If a guy has a slow leak, then it's something he knows about and if the tire then went flat while driving down the road, then that guy needs more common sense than a compressor can give. That aint you, I'm guessing.

My Dad used to have one of those little 12V jobs...stayed in the car. I haven;t seen it in more than 30 years. I say get a 110V compressor and leave it in the shop.

On your riding mower, use the garden hose. You're not going to hurt anything. Just use the hose open-ended with very little pressure. Get it wet, put some baking soda on it and terminals, wait 10 min, scrub with a toothbrush, and rinse. The mower will be fine.

Good luck.