I'm under 160# but I'm a mechanical engineer and I like to have plenty of structural margin, so for my main commuting bike I built up a heavy duty 40-spoke 700C rear wheel (running 28mm tire). The last kind of avoidable failure I want to have when on a long ride, especially commuting, is a broken spoke. The extra mass of the heavy duty wheel is negligible, in relation to the peace of mind it provides me.