Towing rules for agricultural tractors and trailers
What you need to know
This page offers information on the towing and plating rules for agricultural tractors and their trailers.
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Manufacturer's plate
A manufacturers plate is a plate attached to a tractor containing: VIN No., manufacturer’s name, design gross vehicle weight (DGVW), permissible axle loads and towable masses.
Authorisation plate
An authorisation plate is a national weights and dimensions plate on an agricultural trailer containing: Manufacturer’s name, VIN No., maximum design speed, permitted laden weight, maximum drawbar loading, vehicle length and width.
Plating rules
| Year of manufacture | Requirements |
| Manufactured on or after 1 January 2016 | They must be plated. |
| Manufactured before 1 January 2016 | They will only need to be plated if: The agricultural tractor has a maximum design speed of more than 40 km/h or is being used to draw a tandem or tri-axle rigid drawbar trailer with a laden weight over 19 tonnes for tandems and 22.5 tonnes for triaxles. The agricultural trailer is capable by design of being drawn at speeds over 40 km/h or is operating at laden weights exceeding 19 tonnes for tandems and 22.5 tonnes for triaxles. |
For more information Download and read our Revised Standards for Agricultural Vehicles.
How to find out what your vehicle can tow
To find out what your vehicle can tow, you will need to check the manufacturer's plate (see picture below). This is usually located in the cab, under driver’s seat or over the brake pedal, but may vary depending on the manufacturer. If the trailer is fitted with an authorisation plate (pictured on the right above), you must adhere to the lesser of the two weights.
If your tractor does not have a manufacturer's plate fitted, then it is limited to towing a trailer with a DGVW* of not more than three times the tractor’s unladen weight as specified by the manufacturer. Alternatively, you can contact the manufacturer or authorised distributor to have one fitted. You must always adhere to the lower weights declared on the manufacturer’s plate on the tractor or the authorisation plate on trailer.
*The design gross vehicle weight (DGVW) of a vehicle is its gross weight laden with the heaviest load it can carry according to the design specifications.
Frequently asked questions
It is usually located in the cab under driver’s seat or over the brake pedal, but this may vary depending on the manufacturer.
You must adhere to the lesser of the two weights.
To find out the maximum weight your trailer can carry, subtract the trailer’s unladen or empty weight from its maximum permitted weight as shown in the diagram below. However, the maximum weight cannot exceed the weight limits as outlined in S.I. No. 5/2003 - Road Traffic (Construction and Use of Vehicles) Regulations 2003. If you are still unsure, contact the vehicle manufacturer or authorised distributor.
On the side of the drawbar near front of trailer.
Find the unladen weight of your trailer from manufacturer or distributor or have it weighed and its volumetric carrying capacity.
Multiply the volumetric carrying capacity by the density of the crop being carried. Contact your local agricultural adviser who will assist with various crop densities.
Add the figure to the trailer’s unladen weight.
This will give an estimate of laden weight of trailer in kgs.
For example:
A 20ft (6.096 m.) tandem axle grain trailer with a volumetric capacity of 23 cubic metres (m3) and an unladen weight of 5,200 kg would weigh 22,450 kg when level-loaded with wheat:
Unladen weight + (carrying capacity x crop density) = loaded weight.
5 ,200 kg + (23 x 750) = 22,450 kg.
You can contact your local authority to find the nearest weighbridge to you.
This must only be carried out by the original manufacturer or authorised distributor.
This can be carried out by another recognised trailer manufacturer if they are willing to plate it for you.
If the manufacturer is no longer in business and the authorised distributor is unable to determine the age of tractor, you will be limited to towing a trailer whose DGVW* is not more than three times the unloaded weight of the tractor.
*The design gross vehicle weight (DGVW) of a vehicle is its gross weight laden with the heaviest load it can carry according to the design specifications.
Most vintage tractors would not be capable by design of exceeding 40 km/h however, if they can or are being used to draw a tandem or tri-axle rigid drawbar trailer with a laden weight over 19 tonnes for tandems and 22.5 tonnes for triaxles then they would need to be plated.
No. However operators of this type of equipment must adhere to the equipment manufacturer’s specifications provided that the equipment when laden is not heavier than the manufacturer’s rated towing capacity of their tractor.
In this case your tractor or trailer combination is considered to be used in a commercial capacity and therefore all the rules that apply to commercial vehicles will apply here. The trailer must also meet the plating requirements for commercial vehicles as set out in CVRT Manuals. For further information email [email protected].
No. The only time you can use it in public is when you are bringing it to a plating centre and have a new plate fitted. Even then you must not carry a load and you must have an appointment date.
IMPORTANT! This content is for general information only. It does not, and is not intended to, provide legal or technical advice or to represent a legal interpretation of the matters it addresses.