Factsheet 13d — February 2005

Printable version

Trailers: Light simple trailers

What is a light trailer?

Light trailers are vehicles:

• without motive power (ie, they don't have pedals or a motor to drive the wheels)
• with a maximum gross vehicle mass (usually specified by the manufacturer) of 3,500 kilograms or less. (The gross vehicle mass includes the maximum load that the trailer can carry.)

'Light trailers' includes class TA trailers (up to 0.75 tonnes) and class TB trailers (0.75 tonnes to 3.5 tonnes).

What is a simple trailer?

A simple trailer is the most common type of light trailer. Most boat trailers, caravans, and garden trailers are simple trailers.

A simple trailer has one, two or three axles arranged close together in an axle set. This is attached to the towing vehicle behind the axle closest to the rear of the vehicle.

For details on other types of trailer (full, semi, simple, pole, A- and B-train), read Factsheet 13c, Trailers: Full, semi, simple, pole, A- and B-train.

All the dimension requirements for heavy trailers in Factsheet 13c apply to light trailers, except that:

• light trailers have no minimum ground clearance (but if the suspension has been modified to less than 100 mm ground clearance, it will have to be approved by a Low Volume Vehicle Certifier)
• vehicles towing light trailers don't have to meet the tow coupling positions specified for heavy trailers
• the maximum rear overhang for light trailers is 4.0 metres.

Loading your trailer safely

If you tow a simple trailer, you need to be aware that the trailer can impose a large weight on the rear of your vehicle. This weight can, by lever action through the chassis of the vehicle, reduce the effective mass bearing on the front axle(s) of your vehicle. It is important, therefore, that you load your trailer carefully so the load is distributed centrally over the axle(s) of the trailer. This will allow your vehicle to maintain front-wheel grip on the road, so you can continue to steer it safely.

Note: There needs to be a small downward force on the tow coupling of a simple trailer, to ensure it remains stable while being towed.

Maximum width for a light simple trailer

The maximum width for a light simple trailer (including its load) is 2.5 metres (excluding side marker lights and direction indicators and the bulge towards the bottom of the tyre). An additional 25 mm is allowed on each side of the vehicle for ropes, lashings, straps, chains, connectors and tensioning devices that are neither permanently nor rigidly fixed to the vehicle; or J-hooks (to secure stock crates or bins).

Overall length for a light simple trailer

The maximum overall length for a light simple trailer (including drawbar and load) is 11.5 metres. For a towing vehicle and simple trailer combination (including load, but excluding collapsible mirrors), the maximum length is 20.0 metres.

Maximum height for a light simple trailer

The maximum height for a light simple trailer (including load) is 4.25 metres. You're allowed an extra 25 mm above 4.25 metres for tarpaulins, covers and lashings, straps, chains, covers and related connectors and tensioning devices which aren't permanently or rigidly fixed to the vehicle.

All vehicles must be loaded in a safe manner, with a height appropriate to the type of load.

Rear axis specifications

If the trailer has only one axle, the rear axis is at the centre of that axle.

If the vehicle has two axles in a set, the rear axis is midway between the centres of the axles.

If the vehicle has three axles in a set, the rear axis is midway between the extreme axles of the set.

Maximum forward distance

For a simple trailer, forward distance means the distance from the rear axis of the trailer to the centre of the point of attachment on the towing vehicle.

The maximum forward distance is 8.5 metres.

Maximum rear overhang

Rear overhang means the distance from the rear axis to the rear of the vehicle or its load, whichever is greater. The maximum for all light trailers is 4.0 metres.

Minimum ground clearance

There are no minimum ground clearance requirements for light trailers (but if the suspension has been modified and the ground clearance is less than 100 mm, it will have to be approved by a Low Volume Vehicle Certifier).

Maximum front overhang

For simple trailers, front overhang means the distance from the centre of the tow coupling to the foremost point of the vehicle (including its load). The maximum for light simple trailers is 2.04 metres radius arc ahead of the tow coupling.

Tow coupling requirements

It is the driver's legal responsibility to ensure the trailer is safely and securely attached to the towing vehicle by an adequate tow coupling.

For a vehicle towing a light simple trailer, the tow coupling position can't be more than the maximum rear overhang allowed for that type of towing vehicle (see the appropriate factsheet for the towing vehicle — Factsheet 13 provides a guide to the factsheets in this series, and there is a factsheet index on www.landtransport.govt.nz or in print (Factsheet 60) from Land Transport New Zealand agents).

Please note that the maximum allowable length and forward distance of rigid motor vehicles is less if they are towing a trailer.

Intervehicle spacing

Intervehicle spacing means the distance between the towing vehicle (excluding the tow coupling shroud) and the trailer (excluding the drawbar but including the load). The maximum for light simple trailers is 4.0 metres.

There's no minimum spacing. The trailer (or its load) can overhang the towing vehicle.

Outside turning circle

The combination rigid vehicle and trailer or trailers (excluding collapsible mirrors) must be able to complete a 360 degree turn, to the left and to the right, within a circle of 25.0 metres diameter (wall to wall).

No part of a vehicle in a combination, other than its tow coupling, may come into contact with another vehicle in the combination.

The number of trailers you can tow

A light rigid vehicle may only tow one trailer.

Light tractors may tow two light trailers if the manufacturer's rating on the tractor allows this, and if the tractor doesn't exceed 50 km/h.

A heavy rigid vehicle (but not a bus) may tow two trailers under certain conditions.

See Factsheet 13c, Trailers: Full, semi, simple, pole, A- and B-train, for more information on towing two trailers.

Requirements for passenger service vehicles towing a trailer

A heavy passenger service vehicle (eg, a bus) may only tow one light trailer with a gross vehicle mass up to 3.5 tonnes.

A light passenger service vehicle (eg, a van or taxi) may only tow one light trailer with a gross vehicle mass under 2.0 tonnes.

An articulated bus may not tow a trailer.

Speed of vehicles towing simple trailers

• Light vehicles towing a trailer are limited to a maximum open road speed of 90 km/h.
• Heavy vehicles towing a trailer are limited to a maximum open road speed of 90 km/h.
• School buses are limited to maximum open road speed of 80 km/h.

Drivers also need to obey any lower speed limits that apply on particular roads.

What to do about projecting loads

Vehicles may carry loads that are higher, longer or wider than the vehicle itself, provided the load doesn't exceed the maximum permitted dimensions for that class and type of vehicle, and provided the vehicle can be moved safely when loaded. It's the operator's responsibility to ensure the load is properly secured to the vehicle so the vehicle remains stable at all times.

You need to read Factsheet 53, Overdimension vehicles and loads, if the load exceeds any of the standard dimension limits.

Loads that overhang the outside of the body or deck of the vehicle by more than one metre to the front or rear, or more than 200 millimetres to the left or right side, need to carry special warning devices attached to the overhanging end(s) of the load.

During the hours of daylight, there must be either:

• a clean white, or fluorescent red, orange or yellow flag, at least 400 mm long by 300 mm wide, or
• a frangible hazard warning panel, at least 400 mm long by 300 mm wide, showing an orange diagonal stripe (200 mm wide) against a yellow green background, facing forwards or rearwards.

During the hours of darkness, the flags or hazard panels must be replaced with lights attached to the load.

• Loads more than one metre wide and extending more than one metre from the rear of the vehicle must have one red lamp (facing toward the rear) on each side of load.
• Loads up to one metre wide and extending more than one metre from the rear of the vehicle must have one red lamp (facing toward the rear) at the centre of load.
• Loads more than one metre wide and extending from the front of the vehicle must have one white or amber lamp (facing toward the front) on each side of load.
• Loads up to one metre wide and extending more than one metre from the front of the vehicle must have one white or amber lamp (facing toward the front) at the centre of load.
• Loads extending more than 200 mm beyond the side of the body of the vehicle must have one red lamp (facing toward the rear) on each side of the load at the rear and one white or amber lamp (facing toward the front) on each side of the load at the front.

These lights need to be clearly visible in clear weather at a distance of at least 200 metres during the hours of darkness.

Displaying these lights at night is an operating requirement that applies to all vehicles, no matter when they were first registered.  

In the diagram above, the boat is the load on the trailer. It has a raised outboard motor that projects more than one metre behind the rear of the trailer.

If the distance from the rear of the trailer to the most rearward point of the load is more than one metre (and the projecting part is less than one metre wide), one warning device must be attached to the centre of the projecting part of the load:

• In daylight, this may be a flag or hazard panel (facing backwards).
• During the legal hours of darkness, this may be a red light visible from at least 200 metres away.

Where you can find out more

See the Land Transport New Zealand publications Towing and loading safely and Glovebox guide to safe towing and loading.

Contact Land Transport New Zealand:

• Email us: info@nzta.govt.nz.
• Phone our Helpdesk: (freephone) 0800 699 000.
• Write to us: Land Transport New Zealand, PO Box 2840, Wellington.