Matter of taste, I suppose. But 1.5 is the equivalent of a pretty fat road tire. I am not a loaded tourer, so take my guesswork for what it is, but I think most loaded tourers go with tires that are narrower than that. For comparison, I am pretty heavy (230#) and I ride 1.25 on a couple of MTBs converted for road use, and they have more than enough beef to keep my rims off the ground.
jim
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Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
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