TUBE FRAME FAILURE. WELD CONNECTING LOWER TUBE BROKE AWAY FROM TUBE BODY CAUSING ADDITIONAL STRESS TO UPPER TUBES RESULTING IN STRESS CRACKS IN THE SIX O'CLOCK NON VISIBLE AREA. ADDITIONAL USE OF THE TRAILER AT 50% LOAD CAPACITY RESULTED IN FAILURE OF THE REMAINING TUBES WHILE TOWING. CAUSING TRAILER AND MOTORCYCLE TO FLIP AT SPEED , CROSS 2 LANES OF TRAFFIC AND COMING TO REST AGAINST CENTER DIVIDER. RESULTING TO TOTAL LOSS OF TRAILER AND MOTORCYCLE.