The invention relates to a trailer coupling for a motor vehicle (11), in particular a passenger car, comprising a retainer (20), which is arranged on or can be fastened to the motor vehicle (11), and a retainer part (30), which can be detachably fastened to the retainer (20) and which has a retainer insertion projection (33) for inserting into a retainer insertion receptacle (24) of the retainer (20), wherein the retainer part (30) has an integrated locking device (70) having at least one locking body (71) and has an actuation body (73), which is supported in the retainer part (30) so as to be movable in order to actuate the at least one locking body (71) into a locking position (R), wherein the at least one locking body (71) interlockingly engages in a locking receptacle (72) on the retainer (20) in the locking position (R) and is moved out of the locking receptacle (72) in a detaching position (L), the retainer insertion projection (33) of the retainer part (30) therefore being interlockingly locked in the retainer insertion receptacle (24) of the retainer (20) in the locking position (R) of the at least one locking body (71) and being removable from the retainer insertion receptacle (24) of the retainer (20) in the detaching position (L), wherein the retainer part (30) is provided for forming a coupling arm (15), which has a coupling part (60) having a coupling element (65), in particular having a coupling ball, for coupling a load carrier (200) or a trailer, or is provided for directly coupling a load carrier (200). According to the invention, the retainer part (30) has a receiving sleeve (40) having a tubular coupling insertion receptacle (41) for inserting a coupling insertion projection (66; 266) of the coupling part (60) or of the load carrier (200).