Motor-vehicle wheel support unit, comprising a first base body provided with attachments for connection to arms (3, 4, 6) of a motor-vehicle suspension, wherein: - said wheel support unit further comprises a second body for rotatably supporting a wheel hub, which is separate with respect to the first base body and is secured to the first base body in one of two different selectable mounting positions, which correspond to two different vertical positions, with reference to the condition of use, of the axis of the wheel hub, with respect to the first base body, and - the first body and the second body are configured so that in each of the two different selectable mounting positions, the second body is rotated by 180°, around an axis parallel to the axis of the wheel hub, with respect to the other mounting position, - the second body for supporting the wheel hub has holes for engagement of screws for securing the second body to the first base body, these holes being arranged symmetrically both with respect to a median horizontal plane (X-X) of the second body, and with respect to a median vertical plane (Y-Y) of the second body, so as to enable the second body to be mounted on the first body in any of said two mounting positions, which are rotated relative to each other by 180° around an axis parallel to the axis of the wheel hub, - the second body includes an annular cylindrical portion for rotatably supporting the wheel hub, which has its axis vertically offset with respect to said median horizontal plane (X-X) of the second body, said wheel support unit being characterized in that: - the first base body has a central aperture with a vertically elongated oval shape, for receiving therewithin said annular cylindrical portion of the second body whatever is the selected mounting position of the second body with respect to the first body. - said wheel support unit further comprises a second body for rotatably supporting a wheel hub, which is separate with respect to the first base body and is secured to the first base body in one of two different selectable mounting positions, which correspond to two different vertical positions, with reference to the condition of use, of the axis of the wheel hub, with respect to the first base body, and - the first body and the second body are configured so that in each of the two different selectable mounting positions, the second body is rotated by 180°, around an axis parallel to the axis of the wheel hub, with respect to the other mounting position, - the second body for supporting the wheel hub has holes for engagement of screws for securing the second body to the first base body, these holes being arranged symmetrically both with respect to a median horizontal plane (X-X) of the second body, and with respect to a median vertical plane (Y-Y) of the second body, so as to enable the second body to be mounted on the first body in any of said two mounting positions, which are rotated relative to each other by 180° around an axis parallel to the axis of the wheel hub, - the second body includes an annular cylindrical portion for rotatably supporting the wheel hub, which has its axis vertically offset with respect to said median horizontal plane (X-X) of the second body, - the first base body has a central aperture with a vertically elongated oval shape, for receiving therewithin said annular cylindrical portion of the second body whatever is the selected mounting position of the second body with respect to the first body.