Under EC (and AETR) rules "maximum permissible weight" of a vehicle means either the maximum permissible gross weight of the vehicle and that of any trailer (added together) or the towing vehicle's maximum permissible train weight, whichever is the less (see Art 1(6) of EC Council Regulation EEC/3820/85 of 20th December 1985 as amended).

"AETR" refers to the European Agreement concerning the work of crews on vehicles engaged in International Road Transport (Cmnd 7401) (as amended by Cmnd 9037).

For relevant general information see Specific employments/coach and lorry drivers .