Tire Blowed Up!

So I will have to admit that I underestimated Senia's driving skills. Her car had a blow out on the freeway, and she actually didn't panic! It was the left rear tire and she actually drove about a mile and a half to the nearest exit and called AAA after exiting. I was always afraid of this happening, so I tried to keep a good set of tires on her car. Unfortunately I probably should have gotten some better tires, but last year I ended up buying Westlake tires for her car, a Chinese product. I can't for sure say that the cause of the failure was a manufacture defect because I don't know if the tire pressure was good (last time I checked was like a month ago). So I can't totally rule out under inflation as a contributing factor.