Our 6X12 open trailer wears the tires out fast. Trailer is level and load distributed evenly. Has load range C tires on it and we are never over 3000 pounds so the C rated tires rated at 1800 each "should" be sufficient. Tire pressure I run slightly over inflated at 40psi. BUT the outside edge and inside edge wears out very quickly on both tires? I get about a year out of a set before the cords start showing along the edges. This leads to me think they are under inflated but clearly they are not. Do you guys think a D rated tire would have a better contact patch and hold up better? Which tires have you had good luck with?