[Canonman]

Good to know you realize you're towing on borrowed time. Looks like tread separation to me. May have been caused by low pressure and hot temps combining to create the failure. the tire experts on this forum will likely have a more detailed response to your question.
A new set of quality tires all round would be in order. Also I'd highly recommend adding a TPMS so if there is a tire pressure or temperature issue in the future you'll have sufficient warning to safely get off the road, hopefully before any catastrophic failure or damage occurs.
As for covering the damage, that will fall to the insurance company. Extended warranty will be worthless for this issue.