As a rule of thumb, the softer the surface you plan to ride, the wider the tire. Heavy lugged tires will suffer on pavement and smooth tires will suffer in mud. Continental and Schwalbe both make touring tires and I'm sure you'll find a host of others. I ride with 1.75" wide Marathon Plus by Schwalbe. If you're on a expedition and you need a tire face it, your going to use what you can get your hands on which may not be the best tire ever but a sound tire is better than no tire. You have to decide where you'll do most of your riding and find a tire that fits the most situations you anticipate yourself being in. My advice is to look for a tire that is a good all rounder like the Travel Contact or one of the Schwalbe's touring tires. The Schwalbes (I think) are expensive to purchase but it's not unheard of to get 10,000 miles out of a set.