Ever towed with the tires underinflated? (Not just at the time of the blow out, but at any time while using these tires?)
Ever exceeded the speed rating of the tires (probably 65)? (Not just at the time of the blow out, but at any time while using these tires?)
Ever exceeded the weight capacity of the tires? (Not just at the time of the blow out, but at any time while using these tires?)
If the answer is yes to any of these, at any time, then you are partly at fault. Even if you don't have a blow out at the time that you exceeded the tires' rated capacities, you can still have done internal damage to the tires that could lead to a blow out later.
