Tire Tread/belt problems of the 2001 Toyota Sienna

I had two incidents of tire failure on the highway where the tires just came apart at speeds of 70 mph. The first tire had about 40k miles on it and the 2nd tire had 50k miles on it. I had a close call, but no accident.

Vehicle failed state inspection due to front tires being unsafe. Due to extreme front tire conditions. The consumer was shown thin tread on the front tires and suggested replacement. The consumer requested reimbursement. )m&s tubeless radial fr 68002).

Tread separated on firestone tire in a similar manner to Ford explorer recalled tires. Took tire to Toyota dealer who initially advised me to take tire to a firestone service center. Later Toyota service department asserted that tread separated because vehicle was driven while tire was not properly inflated. Toyota dealer offered to replace tires however. I still have separated tire and I will take photographs. I intend to keep separated tire in my possession. Approximately 20 minutes prior to tread separation, I put air in tires. I drove on the interstate and about 2 miles off of the interstate is where the tread separated. It is my understanding that this particular tire in not currently part of the firestone recall but I would like your agency to note this report of the problem that I experienced with the affinity tire. (dot number: w2vfaat050 tiresize: p215/65r15).