Tire Bubble problems of the 1997 Plymouth Voyager

I was heading north on scenic highway, north of creighton in pensacola FL doing 50 in a 45 mph zone. Suddenly I heard a very loud bang and the right front tire had a blowout. I managed to stop, change the tire and return it to sears. The writeup man said the right side of the goodyear weatherhandler LS tire probably got an air bubble between the inside and outside of the sidewall and that caused the tire to blow outward, from its sidewall. I got credit for the 3 remaining tires and bought 4 michelins.

While vehicle was parked consumer noticed bubbles on the front driver's side tire. Dealership was notified, but did not resolve the problem. Bridgestone, weatherforce, p215/65r15.