What was found
NOSE TIRE SEPARATION ON ROTATION AT ROTATION NOSEWHEEL VIBRATION INCREASED AND MATERIAL DEPARTED TO THE LEFT FROM THE NOSE WHEEL WELL AREA AND THE VIBRATION INCREASED. WE ELECTED TO LEAVE THE LANDING GEAR EXTENDED DUE TO THE UNKNOWN CONDITION OF THE NOSE GEAR. NO ABNORMAL ENGINE INDICATIONS OR SMELLS NOTED. AN EMERGENCY WAS DECLARED AND WE RETURNED TO DAL. THE LANDING WAS NOT OVERWEIGHT AND LANDING NORMAL EXCEPT FOR EXCESS NOSE GEAR VIBRATION.<[01] R AND R BOTH NLG WHEEL ASSY?S PER AMM 32-45-21. TIRE TREAD LOSS CONDITIONAL INSP ALSO PERFORMED REF TASK ID TTG8Q00X0W6T.