Tractor, commercial vehicle, range of tractors and method for configuring a tractor

A tractor of a commercial vehicle comprising:

• a chassis extending along a longitudinal direction, the chassis having front and rear chassis parts adjoining each other along the longitudinal direction, the rear chassis part presenting opposite outer lateral surfaces, parallel to each other, and a top surface between the outer lateral surfaces,
• a cab with a driving place for a driver mounted on the front chassis part,
• at least two wheel trains at a distance from each other along the longitudinal direction and on which the chassis is mounted,
• a fifth-wheel coupling arranged on the top surface of the rear chassis part and configured to attach a trailer to the tractor, the fifth-wheel coupling protruding from the top surface of the rear chassis part up to a fifth-wheel height,
• lateral fairings covering respectively the outer lateral surfaces of the rear chassis part and configured to fill at least a part of a lower gap between the wheel trains in a vertical direction,
• wherein each of the lateral fairings has:
• a fixed portion attached to the chassis and comprising a base and a support, in addition to the base and having holes,
• a movable portion comprising an extension plate presenting an upper free edge almost parallel to the top surface of the rear chassis part, and
• a mounting arrangement between the fixed portion and the movable portion, the mounting arrangement being configured to vary a fairing height of the upper free edge of the movable portion with respect to the top surface of the rear chassis part in accordance with the fifth-wheel height,
• wherein the mounting arrangement is a discontinuous mounting arrangement configured to move the movable portion in a discontinuous manner with respect to the fixed portion between different mounting heights, the discontinuous mounting arrangement comprising at least one first mounting member arranged on one of the fixed and movable portions, and at least one series of second mounting members arranged on the other of the fixed and the movable portions, the series of second mounting members comprising separate second members aligned at different mounting heights, the first mounting member being configured to cooperate with any of the second mounting members to attach the movable portion to the fixed portion,
• wherein the extension plate of the movable portion is sandwiched between the base and the support.