PEOO 020 ; CONSUMER WAS TRAVELING ABOUT 70MPH ON HIGHWAY AND WAS GOING DOWN A HILL WHEN HE FELT VIBRATION, AND THE LEFT REAR TIRE TREAD SEPARATED. TIRE WAS HITTING UP AGAINST VEHICLE. THERE WERE NO INJURIES. FIRESTONE #ATX, P23575 R15. HE WENT TO FIRESTONE, AND THE PROBLEM WAS TAKEN CARE OFF. *AK