GVM ( Gross Vehicle Mass )
GVM is the maximum the vehicle can legally weigh . This is on the vehicle ’ s placard and is a definite figure that is readily available for all vehicles . It is often the same for all types of a given model but might vary a bit with trim level , engine or body style .
Payload
Payload is the difference between the GVM and tare weight . For example , tare of 2000kg , GVM of 3000kg , payload = 1000kg .
Payload is everything that is put on the truck or it has to carry . That includes bullbars , stronger tyres , roof racks , winches , canopies , storage systems , occupants , camping gear , recovery gear . Typically a modified touring 4WD has gear that weighs 200-400kg , and by the time a family of four has kitted up and is ready for touring you ’ re looking at 900-1000kg . I ’ ve done the maths a few times .
Front and rear axle load
This is how much weight can be placed on either axle . Usually , the sum of the two axles is more than the GVM . For example , in the case of the Ford Ranger , it is 1480kg and 1850kg totalling 3330kg , 130kg more than the 3200kg GVM .
This means there ’ s a bit of flexibility in exactly where the load is positioned over the axles . Beware of some aftermarket GVM upgrades which merely move the GVM to total the sum of the axle ’ s ratings , as then you lose that flexibility .
Braked tow rating
Braked tow rating is how heavy a trailer the vehicle can tow , provided it has trailer brakes as opposed to no brakes in which case it relies only on the towcar to stop the combination . Trailers over 2000kg need brakes that can be independently applied from the tow vehicle .
The braked tow rating is the trailer ’ s ATM , or Aggregate Trailer Mass . That ’ s how much the trailer weighs . The Gross Trailer Mass ( GTM ) is the ATM with the towball mass ( downforce ) subtracted .
For example , a trailer that weighs 2000kg has a 2000kg ATM , and if there ’ s 200kg on the towball the ATM is 1800kg . The ATM is the trailer equivalent of the GVM . Trailers also have an unladen weight , the kerb weight .
GCM ( Gross Combined Mass )
GCM is how heavy the combination of the vehicle and trailer can be . This should be , but isn ’ t always , the sum of the GVM and braked tow rating ( maximum ATM of the trailer ).
Now that ’ s out the way let ’ s look at some numbers , all in kilograms :