Tire Blowout problems of the 2007 Honda FIT

With no precipitating event that we are aware of, the inner sidewall of the left front tire blew out while we were driving at 55 mph on us hwy 93 in western montana on a dry road. All four tires, purchased as a set, had just under 6,000 miles on them and had been rotated by the tire store from which we purchased them just two days before incident and were properly inflated. Upon inspection after incident outer sidewall looks stressed as it, too, was ready to blow. As we expected, the tire dealer has agreed to replace the tire,.