Car had 27540 miles on factory original toyo nanoenergy tires when the rear passenger tire blew out. i was 22 miles into my drive home . no tps warning and i had visually looked at my tires before heading home. the entire tread separated from the sidewalls. the sidewalls stayed with the rim and i was able to safely stop the car on the grass median. this type of sidewall blowout has never happened in all my years of driving. i was on us-321 north bound just after the hardin rd exit going 70 mph at time of blowout. not in a turn but nearly straight line driving. weather was mostly sunny and 65 degrees.