Technical Info

Facts to consider when Constructing a Trailer


Trailers need to be structurally sound and solid, with some weight being exerted downward on the towball of the towing vehicle. The amount of weight required is dependant on the trailer’s size and mass and the towing vehicle’s specifications.

Any trailer cannot be more than 2.5 metres overall in width on the road.

Length cannot exceed 11 metres.

New trailers require a Vin Identification Plate which can be obtained from transport authorities. The following information must be stamped or engraved on it.

a) The Vin number supplied by the transport authority.

b) Date of manufacture.

c) The tare weight of the trailer, (unladen weight). A certificate can be obtained from any public weigh bridge and must accompany the registration paper.

d) ATM or Aggregate Trailer Mass, which is the tare weight plus the load capacity of the trailer. E.g. If the tare or unladen weight of the trailer is 300 kg, you add the load you expect to carry in the trailer (having regard to the capacity of the axles and springs), say 450 kg to arrive at the ATM of 750 kg.

e) Tyre
size, capacity and pressure.

f) Axle or suspension group capacity. This figure should always equal or exceed the ATM by a comfortable margin. E.g. In our example 900 kg to 1200 kg.

Trailers with an ATM exceeding 750 kg are required to have brakes fitted, either mechanical or hydraulic override (Drum or Disk) or electric.

Trailers exceeding an ATM of 2000 kg are required to have brakes fitted on all wheels and a breakaway system that will apply the brakes for 15 minutes, if the trailer becomes separated from the towing vehicle.


All technical information supplied by Trailer Warehouse was correct at the time of printing. We regularly check and up date this page however it is the customers responsibility to confirm all details with the governing state or federal authorities.