The two sidewall blowouts I've had in my life were when the brakes slipped out of adjustment and wore weak spots in the sidewalls. Have you checked to see if some bike part is out of position? I've had tire so old and crumbled in the sidewalls that only the cords were left. No blowouts. I am 5'11" and counting the commuting load nearly your weight. I always use tires rated for touring or commuting, not racing. Thick rubber sidewalls might help.