Properly-built M13s are strong as Hell on steroids and will have no trouble running up to most 28c tires.
I've got 25c Pasela TGs on mine, am a big ape of a dude who rides harder than Henry Rollins raping a water buffalo on the back of a speeding flatbed truck and have no trouble with mine.
Last edited by Scrodzilla; 06-28-11 at 02:52 PM.