Tire Tread/belt problems of the 1998 Ford F-350

While consumer was driving on the highway tread separated from right rear tire. Consumer had not struck anything, and tire was still inflated. He was able to pull to the side, and examined what was left of the tire. He realized that all the tread was gone but sidewall was still intact. It was a wide track baja a/s, lt245/75r16. The road was clear and dry. Ten minutes prior to the failure, the consumer felt vibration shuddering throughout the vehicle. Tire had approx. 35,000 miles on it. Consumer has one of the failed tires, he replaced and discarded the other three.