I need to know a lot more about the spare parts one needs to keep with them for emergencies. "G" added this to the air pressure thread.
http://www.crappie.com/crappie/images/icons/icon1.png
Sure 20 lbs. will get you somewhere....but its better to have the correct pressure. I do carry a 12 volt plug in air compressor with me and also tire plugs and the tools to put them in with. I also carry a complete trailer hub with bearings races and seals installed and packed with grease. I also carry two complete sets of wheel bearings, races , and seals, grease and tools to install them. I don't like having to leave my boat and trailer on the side of the road while I travel around in unfamiliar territory trying to find parts on a Sunday afternoon.
I bought a new aluminum floor jack to keep with me, also a 12v air compressor and the tire plugs but I don't know about the hubs etc. If you were going to carry the least amount of stuff, what would it be?