How to Prepare Box Trailers for Use

How To Prepare Box Trailers for Use

Single axle box trailer

Single Axle Trailer

Please CHECK YOUR TYRES prior to loading.

Trailers must be a suitable size and type for their intended tasks.

The loaded mass of the trailer must not exceed the lesser of:

  • Rated capacity of the towbar and tow coupling
  • Maximum towing capacity of the vehicle.
  • Maximum carrying capacity of the trailer.
  • Maximum rated carrying capacity of the tyres.
  • If the vehicle manufacturer has not specified the maximum towing mass, the maximum towing mass is:
    1. One and a half times the unladen mass of the towing vehicle, provided that the trailer is fitted with brakes which are connected and in working order or
    2. The unladen mass of the towing vehicle if the trailer does not require brakes.
Box Trailers - Dual Axle Trailer

Dual Axle Trailer


The minimum braking system for a trailer depends on the type of trailer, its weight and the weight of the vehicle:

  • 0 – 750 kg loaded weight – no brakes required
  • 751 – 2000 kg loaded weight – braking on both wheels on at least one axle.
  • 2001 – 4500 kg – braking on all wheels, and an automatic breakaway system in case the trailer becomes detached from the vehicle.


It is important that trailers are not overloaded and that loads are properly secured to or contained within the trailer.

A load must not project more than 150mm beyond the trailers width or be more than 2.5m overall width, whichever is less.

Loads that project more than 1.2m behind a trailer must have a red flag attached to the end of the load. This flag must be at least 300 mm square and clearly visible. To avoid having an overhanging load, you should purchase a trailer that suitably contains the load.

Overall length of the vehicle and trailer combination including its load must not be more than 19m.

To reduce sway, heavy loads should be concentrated toward the centre of the trailer.

Loads should be kept as low as possible to the axle of axles with about 60% of the total weight forward of the centre of the axle or axles. As a general rule, about 5-10% of the total mass of the trailer plus load should be supported by the vehicle through the coupling. The trailer drawbar should be level or slightly ‘nose down’