camper trailer & vehicle
tow weights & limits

The laws that apply to vehicle towing weights & limits can be a very confusing subject. As a duty of care to other road users there are a number of laws, rules & guidelines you need to be aware of, otherwise you could be breaking the law & voiding your vehicle warranty or insurance in the event of an accident.

A vehicle & camper trailer must compliment each others maximum capacities making for a safe combination in all situations. This especially applies to lighter vehicles & soft roader 4wds which have lighter tow & ball weight capacities. If the ball weight is too heavy, the tow vehicle's rear suspension will be forced down affecting braking & also the vehicle’s steering when it is most needed, typically during an emergency situation.

the camper trailer

Camper trailer Tare weight is the weight of a camper trailer as it left the manufacturer without water in the tank/s or gas bottle/s filled. Any options that have been ordered & fitted by the camper trailer manufacturer is also included in the Tare.

If you have ordered a camper trailer from an agent of the camper trailer manufacturer, then any options ordered at the agents & fitted by the agent will be payload.

Gross Trailer Mass or GTM is the maximum weight recommended by the camper trailer manufacturer. All components used in the camper trailer build have been engineered with a safety factor for a specific maximum weight capacity, such as the  RHS size & wall thickness of the chassis & A-frame, axle capacity, bearings, suspension & shock absorbers. 

The Tare & GTM of each camper trailer is stamped on the trailers VIN plate located on the A-frame.   

Payload is the weight difference between GTM & Tare. 

Ball weight is listed on the camper trailer manufacturers website of the Tare weight.

A rule of thumb for the camper trailers ball weight is around 10% to 15% of the camper trailers loaded weight which gives a safety net with variable shifting weights as the water tank is emptied, food consumed & firewood unloaded. A camper trailer weighing 1400kg should have a ball weight of 140kg to 210kg.

Some camper trailers have a large kitchen, food storage, fridge box, gas bottles & jerry cans on the A-fame balanced by the two spare wheels & large water tank located behind the axle. You also need to be careful if you have a front mounted grey water tank which transfers water from the rear fresh water tank as the ball weight will become heavier.  

Packing heavy items to the rear to make the ball weight lighter has its own set of problems

 the vehicle

The vehicles towing & a ball weight limits are recommended by the vehicle manufacturer & should not be exceeded. 

Tare of a vehicle is the weight ready for service, unoccupied, with all fluid reservoirs filled to nominal capacity with only 10 litres of fuel, all standard equipment & any options fitted by the vehicle manufacturer.

Gross Vehicle Mass or GVM is the maximum laden mass of a motor vehicle as specified by the manufacturer.

Payload weight of a vehicle includes the occupants, cargo, as well as any accessories such as a bull bar, winch, tow bar, roof racks fitted aftermarket & also includes the ball weight of the trailer.

Ball Weight is the maximum allowable weight to be placed on the vehicle’s tow ball as recommended by the vehicle manufacturer.

Towbar. If an aftermarket towbar is fitted with a lesser tow rating than the vehicle manufacturers recommendations, the most you can tow is the amount which is the least.

Towing Capacity. Maximum towing unbraked & braked capacity is set by the vehicle manufacturer.

Gross Combined Mass or GCM is something you need to take into consideration when pulling heavy camper trailers. GCM is the weight of both the vehicle & the trailer set by the vehicle manufacturer.

more

It is a good idea to weigh your vehicle & camper trailer including the ball weight at a public weighbridge at least once, preferably fully loaded before a trip so you know what the weights are.

It is handy to have a ball weight scale if you are interested in maintaining the correct ball weight http://www.campertrailers.org/towsafe.htm

further reading

a balanced rig https://www.campertrailers.org/balancing_act.htm
towing regulations https://www.campertrailers.org/towing_regulations.htm
a good off road trailer https://www.campertrailers.org/off_road_trailer.htm
 

Rob

 

november 2024