Mike, there are a number of 12v air compressors available; just google the topic. But I found that a 12v takes too long, even when you are just down five or six pounds. Also, getting the compressor close enough to the tire may be a problem, depending upon where you have a 12v socket.

I decided long ago to carry a 120v portable compressor, which works well not only for airing up tires (mine are small 22.5 inch tires and I carry 90 pounds) but also for using the air for blowing out parts that need cleaning, etc. DeVillbiss makes a lightweight 120v AC compressor that will go up to 125 pounds pressure. Of course, if you do not have a generator on board your rig, then you are tied to park or home electrical service and might be able to use only a 12v device. But with a generator on your rig you have all the 120v you need. You can find the new model compressor at http://www.devap.com/products/view.as...

My first compressor was 12v and I finally decided that it was not up to the job. You can find a 120v that will not necessarily be much bigger. Dutch (as usual) made the case.

I too tried the 12V route but soon became disenchanted with it and went with a 150# Husky from HD. Then a couple of years ago I tapped into the air supply on my pusher that runs at 135 PSI. I use a small hose reel and quick disconnects from Harbor freight. Does the job quickly, weighs next to nothing and takes up very little room in my front left compartment. As with all things there are trade offs. In my case I must fire up the coach to air up a tire. I try to not do it during quiet times in a campground.

Bob K from PA