general problems of the 2000 Nissan Pathfinder

I bought new fratera tires (4 in all) on 10/14/05, and was given an 80,000 mile warranty. My vehicle had 61,084 miles when they were purchased. The vehicle now has approximately 86,520 miles and the tires had to be replaced yesterday (8/3/08). Two of the tires were at the limit for being legal on the road. These tires has less than 26k miles and they had to be replaced. My driving habit is not to slam on the brakes, nor is it to spin the tires to where excess rubber is laid on the pavement. I don't even drive very many miles--less than 26k in almost 3 years!!!.

While driving at 40 mph front passenger tire disintegrated, causing loss of control.

While having michelin p255/65 r16 tire inspected for cause of tire noise, discovered inside tire over two dozen irregular shaped balls of rubber compound ranging from 4 to 10 mm in size. Tire dealer could not explain and michelin has not responded to my inquiry. Does this condition represent a potential tire failure problem?.