Tire Tread/belt problems of the 1999 Toyota Pickup

Consumer purchased a set of tires 3 years ago for his Toyota truck, and now after 35,000 miles he is having problems with them separating . These tires are not on recall so the manufacturer will not help him. While driving felt as though he was getting a flat tire, he went to the dealer and after examination of the tires he found out that the tires had separated from the belts inside. Firestone,wilderness 30x950 r 15 lp which was suppose to go from 50-60,000 miles. These tires did not come on the vehicle, but were purchased later.