Tire Blowout problems of the 2006 Chevrolet Silverado

The contact owns a 2006 Silverado with hankook tires, dynapro as size 235/85/r16 (na). She stated the tires were purchased as replacements in 2009. While driving 55 mph, the rear right tire blew; the contact stated this was the second tire that experienced a blowout. The contact stated she changed out the tire with her spare. She did not contact the place where the tires were purchased. The VIN was unavailable. The approximate failure mileage was 5,000 and the current mileage was unknown.