Pretty hard to predict and bring the next part that is going to fail. If you could predict you would change it before you left. At some point I looked back on my history and asked myself what tools and other items that I tote all over creation did I actually use. Those that I did use got invited back. Most have already been mentioned. Also if you are in a group you don't need 4 pairs of vise grips, 4 ratchet straps, 4 tow ropes, etc. You can spread it out over everyone. Like a potluck dinner. Next, what are you really going to do out in the weather, to troubleshoot, diagnose, and repair a malfunction? It's pretty hard in that environment. You will most likely limp it in or tow it.