Tire Sidewall problems of the 2010 Chevrolet Silverado 1500

My truck tires were bought at costco in 2015 and had 70k warranty or 6yrs wcf. My added truck mileage since then is 12k miles. I discovered my driver rear passenger tire go flat . I put the spare and took it to costco for repair. Costco informed me that this is a tire defect as the tire had a side wall perforation. Tire cannot be repaired and a new replacement is required. I looked up michelin tire recalls and found one issued in 2013 about michelin x-radial tires discussing this same defect but it did not include my tire size ( p245/70r17 ) . Fortunately this incident did not occur while driving at high speed.