GVM is the total load the truck can carry on its own wheels. Whereas GCM includes trailer weight. Similarly, GCM (Gross Combination Mass) GCM is the total weight of the truck, trailer and their loads combined. Gross Combination Mass (GCM) is the total weight a truck can carry and tow. This is the maximum weight of a loaded articulated vehicle or combination vehicle such as a prime mover with semi-trailer and trailers. Also referred to as GCW (Gross Combination Weight).
Link to National Heavy Vehicle Regulator ( click here )