What was found
ON TAKEOFF ROLL, A THUMP WAS HEARD ACCOMPANIED BY BUMPING. PILOT IMMEDIATELY LIFTED OFF. PILOT FLEW AROUND FOR ABOUT 3 HOURS TO BURN OFF FUEL AND THEN RETURNED. AFTER UNEVENTFUL LANDING (TIRE STILL HOLDING PRESSURE), FOUND CENTER SECTION OF RETREAD CAP HAD PEALED OFF. THE ORIGINAL RUBBER UNDERNEATH WAS SMOOTHER THAN THAT ALONG SIDES AS THOUGH IT WAS NOT SCUFFED ENOUGH SINCE ITS INSTALLATION. ONE PILOT REPORTED THE TIRE AS VERY OUT OF BALANCE ON MULTIPLE OCCASIONS.