2001 Ford Escape tires problems

I was driving my car on I-75 near gainesville, florida last week. I was in the passing lane when I heard and felt the left rear tire tread beating on my car. It had separated from the tire without warning. It all happened so fast, I immediately attempted to get onto the shoulder safely. My car began to pull to the left uncontrollably, crashed into the guard rail at over 60 MPH, bounced off and sent me sliding sideways for about 100 feet. By the grace of god, my children and myself were not physically injured.

I have had three different tires exchanged on my vehicle since the purchase date of feb. 7 2001. I have taken my car in every 5000 miles for service and everytime I have left the dealership the car pulls immediately to the right. I have gone back to the dealership eveytime and voiced my complaint. At 15000 miles the tire manager explained it was my tires and had me purchase a set of 4. At 35000 miles the dealership replaced the tires again this time at no charge. I am now at 64000 and third set of tires.