Tire Tread/belt problems of the 1999 Mercury Sable

While traveling at approximately 35 miles per hour on a two lane road I saw a tire tread shoot in front of my vechicle. I then heard a loud noise coming from the rear of my automobile I attempted to pull over and stop. The entire cap part of the tire was missing. Only the side walls remained. It took me quite some time to obtain tow service because I has in a dead zone for my cell phone. The tow truck driver which changed my tire said he would take care of the old cap. I was so tired from this ordeal and long wait for the tow truck after having to walk until I was able to get a cell signal that I did not think to save the cap. Controlling the car to a stop was very stressfull. There is damage to the mag whell and to the guards that surround that tire. I had the dealer examine the remaining 3 tires but found them to look ok. The car had been serviced by this dealer at a little of 35000 miles. I am fearfull that the remaing tires will fail without warning. The dealer took digital photographs to be forwarded to the engineers at Ford. (dot number: adur442368 tiresize: p205/65r15).