I think the bigger question is what kind of surfaces will you be riding on and how much weight are you carrying. My salsa marrakesh came with 40mm marathon pluses. changed them out for a few different types of tires due to they're weight. I only use 38, 40mm tires right now. I recently finished a 6 day 900Km tour in Ontario and my ride had a mixture of good pavement, really bad pavement and, and about 100Km of gravel. There were a few times i wished i had bigger tires. the 700x38 tires i used held up but i really think that a 40, 42mm on the right rim would be the best option. Going for light weight while touring to me is kind of silly. I don't want a puncture going down a rough hilly road loaded down. Touring isn't supposed to be fast anyway