Tire Sidewall problems of the 1996 Ford Mustang

I have had to replace all 4 of these tires at a cost of 685 dollars to myself. The tires are coming apart at where the tread meets the sidewall much the same as the firestone tires that are being recalled. I took the vehicle into pauls tires in marion indiana and they would not replace them because fincannon Ford did not buy the warranty. I then took them to another kelly dealer here in muncie. They called kelly and kelly denied any other complaints of this and I was charged for the replacemnet of the tires. The first ones to go bad were the front tires. Now the passenger rear is doing the same thing. I would think that people should be aware that firestone is not the only manufacturer having this separation problem. Had I not have been putting brakes on this car I would not have even noticed that the tires were separating. Most people do not look at the tires on their car. (tiresize: p255/40r17)( dot number: tire size: p255/40r17 ).