>>937192In the first world it doesn't matter. If you're going into the third world, finding replacement wheels/tires at 26" is easier from what I understand. 26" will give you slightly easier pedaling at the same gear ratio.
I couldn't tell you if it's actually possible to find quality tires in the third world. My thought is to arrange for new tires to be mailed to me every 5000 miles or so once I get around to adventuring internationally (25,000+ miles of touring in NA). That's about as far as my touring tires have lasted me (Schwalbe Marathon Mondials, Infinity Armadillos). Switching front and rear tires part way is a good idea because a rear tire with more weight on it will wear faster.
