WHILE DRIVING A 19969 CADILLAC, FLEETWOOD AT 55MPH RIGHT FRONT TIRE TREAD STARTED TO UNRAVEL. THIS CAUSED VEHICLE TO HIT A CEMENT BARRIER & WENT INTO AN EMBANKMENT. THIS HAS ALSO HAPPENED ON AN 1982 CADILLAC, FLEETWOOD WHERE THE RIGHT FRONT TIRE HAD A BLOWOUT, BUT NO TREAD. 4 TIRES ON THAT VEHICLE HAD TREAD UNRAVELLING. RIKEN P235/75R15 RADIAL WITH 8,000 MILES.*AK