A trailer coupling comprises a cross member unit, which is mountable on a tail region of a body, and a bearing unit held by the cross member unit. A ball neck with a coupling ball is held on the cross member unit by the bearing unit. The cross member unit is connected in its two outer, mutually opposed end regions to mounting elements for fixation to the tail region. The cross member unit has an upper supporting structure and a lower supporting structure. The supporting structures are each connected at their mutually opposed outer end regions to the mounting elements and in a central region carry the bearing unit. One of the supporting structures is primarily torsionally rigid and at least partially surrounds a structure interior, and that the other of the supporting structures is primarily tensile stiff in the direction of travel.