Tire Sidewall problems of the 1999 Toyota Sienna

At 65mph, tire sensor indicated problem. Upon removing the front left firestone affinity tire, found a 7. 5" separation between the tread and the interior sidewall, with the steel belt in view. Further inspection revealed similar wear on front right tire. Normal pressures and alignment had been maintained through routine service. Local firestone dealer claims tire was not defective, despite Toyota indications to that effect and similar experiences with other firestone tires. Although I have replaced all four tires, I have retained the defective tire to support investigation. Digital photos of the tire are also available. (dot number: w2vfait099 tiresize: p215/65r15).

Sidewall of tire delaminated or separated. (dot number: w2vf tiresize: p215/65r15).

All 4 tires on vehicle have "bulges" on the exterior sidewalls, did not check interior sidewalls. The left side bulges are the worst, the front being the worst of all. The bulges are nearer to the tread than the center of tire. There are apprx 3 to 5 bulges around the perimeter of the tires. There is no noticible performance issues at this time, but having all tires like this makes me very nervous. I did have a sidewall failure a few months after I purchased the van, but I attributed it to a low speed bump into a low curb as I was making a right hand turn into a gas station. (dot number: w2mof61019 tiresize: p205/70r15).