I know you say your air pressure is correct but make sure the air pressure is for LOADED trailer. THe tire pressure ratings on the tires is for empty trailer. Add the weight of boat,trailer, gas, gear, etc and your air pressure will be too much. I blew out a brand new tire on it's first ride (5+ hours) because I had too much air in the tires and balooned them causeing the centers of the tire to thin out.