Along with PLYs and LOAD range, check the sidewall for "SPEED" rating . . not rating sidewall, then it's max 60mph. They have ratings I believe, at 60mph, then 65mph, 70 and 81mph . . . note that I am towing at 75 or 80mph but having the "cushion" of maximum ratings, feels better than running 60mph on a 60mph rated tire.