What was found
IN FLIGHT - L1 TIRE-DIFF PRESS AND TIRE PRESS LOW - THE #6 TIRE SLOWLY DROOP PRESSURE (OVER 30 MINS) TO 49 PSI AND TIRE FAIL L-2 ON #6 ALERT. WE RETURNED TO MIA AND LANDED. FOLLOWED TIRE FAIL CHECKLIST, THE #6 TIRE WAS FLAT BUT NO VISUAL DAMAGE TO AIRCRAFT. INSPECTED LDG FOR DAMAGE, NO HIDDEN DAMAGED FOUND. REPLACED #6 TIRE ASSEMBLY IAW MD-11 TASK 32-41-01-000/400-801. #5 MAIN WHEEL REQUIRES REPLACEMENT. REPLACED #5 TIRE ASSY IAW MD-11 TASK 32-41-01-000/400-801.