DfT Requirements for Trailers and Towing

Department for Transport guide to legal requirements for trailers and towing


Requirements regarding trailers used on the road are given in the Road Vehicles (Construction and Use) Regulations 1986, as amended (C&U) and the Road Vehicles Lighting Regulations 1989, as amended (RVLR).   The following is a summary of the main requirements.

1 Weight

In the case of light trailers, that are less than 3500kg in maximum laden weight, there is not any specified relationship in UK law between the weight of the towing vehicle and the weight of the trailer.

For M1 category vehicles (motor vehicles used for the carriage of passengers and comprising not more than eight seats in addition to the driver's seat) the maximum permissible trailer weight is quoted by the vehicle manufacturer.   If this is exceeded it is possible that the Courts or Insurance Companies may take the view that this constitutes a danger.

The maximum laden weight of a trailer, which may be towed by a light goods vehicle depends on both:

Neither the maximum permissible trailer weight nor the maximum gross train weight (the laden weight of the trailer plus the laden weight of the towing vehicle) should be exceeded.  

It is possible that the stated gross train weight is less than the sum of the stated maximum permissible laden weight of the towing vehicle and the stated maximum permissible laden trailer weight.   In this case the towing vehicle and the trailer must be loaded such that each does not exceed its individual maximum limit and the sum of both does not exceed the maximum gross train weight.

It is not a requirement to display a notice of the unladen weight of the trailer or the towing vehicle, unless the towing vehicle is either a motor tractor or a locomotive, as defined in the C&U.

2 Dimensions

If the towing vehicle has a permissible gross weight in excess of 3.5 tonnes the maximum width and length of the trailer are 2.55 metres and 12 metres respectively. If, however, the gross weight of the towing vehicle is 3.5 tonnes or less, then the maximum permissible width and length are 2.55 metres and 7 metres respectively.   In both cases, the overall length of the towing vehicle and trailer must not exceed either 18m or 18.75m depending on the type of towing vehicle.  

The definition in C&U of the overall length of a trailer makes it clear that the coupling device and draw-bar are not included in the length dimension. In the case of a caravan, where a protective box is mounted on to the front, which is supported on the draw-bar for the purpose of storage gas tanks, for example, this box is included in the overall length.

These requirements also apply to visiting vehicles.   Under Regulation 4(4) Item 2 of C&U, we permit a vehicle to be brought into Great Britian by a person resident abroad, provided that the vehicle complies in every respect with the requirements relating to motor vehicles or trailers contained in:

Therefore we provide visiting vehicles an exemption from the construction, equipment and maintenance of vehicle requirements specified in Part II of C&U but not from the requirements for Regulations 7, 8, and 10, which relate to length, width and height respectively.

There is significant harmonisation of regulation within the European Union and freedom of movement across boarders. European Council Directive 96/53/EC, Annex I, states the maximum authorised dimensions for certain road vehicles circulating within the Community. However Annex I relate to large passenger carrying vehicles, large goods vehicles and trailers with a weight of over 3500 kg. There are no specific requirements for light vehicles.

Article 3(2) permits Member States to restrict vehicles, not covered by Annex I, put into circulation in their own territory to be in conformity with their own national requirements.

The UK is permitted to refuse to admit vehicles into the UK if the dimensions exceed limits fixed by the domestic legislation, Annex 1 (1).

3 Brakes

Braking requirements are prescribed in Regulations 15 and 16 of The Road Vehicles (Construction &Use) Regulations 1986 as amended.  

4 Lights

The requirements for trailer lighting can be found in The Road Vehicles Lighting Regulations 1989 as amended (SI No.1796).   A copy can be obtained from The Stationery Office, or see Section 6 below.

5 Coupling devices (Tow Bars)

Any coupling device fitted to a passenger carrying vehicle with up to eight seats plus the driver that:

       a)   has European Whole Vehicle Type Approval (ECWVTA) and

       b)   that the manufacturer has authorised to tow a trailer and

       c)   is first registered on or after 1 August 1998

must be type approved in accordance with EU Directive 94/20/EC.   (Regulation 86B of the Road Vehicles (Construction and Use) Regulations 1986, as amended)

Modification to the coupling in any way, for example, by the addition of other devices that alter the position of the centre of a coupling ball, will render the approval invalid unless the coupling device manufacturer has taken this into account during approval of the device.   You will need to consult the manufacturer for advice.

A vehicle that has ECWVTA will have a Vehicle Identification Number plate (VIN plate) bearing the vehicle manufacturer's name, chassis number and an approval number including the letter "e" in a small rectangle.

If the manufacturer has not authorised the towing of a trailer by declaration during the type approval process, it is not permitted to fit a coupling device or tow a trailer.

6 Legislation

The Regulations referred to above may be obtained through the Stationery Office under the references, SI 1986 No.1078 for the Construction and Use Regulations and SI 1989 No. 1796 for the Lighting Regulations.   However, there have been many amendments to these base Regulations and it is important to obtain all of these in order to have the current situation.   

As an alternative, you may find it easier to visit a good, city based, reference library where there may be a copy of The Encyclopaedia of Road Traffic Law and Practice, published by Sweet and Maxwell.   This publication tracks the amendments to legislation and presents them in an up-dated form.   One of the volumes will contain both the Construction and Use and Lighting Regulations.

The RVLR amendments together with amendments to C&U from 1988 can be found as Statutory Instruments on the following web site:

7 Other considerations

The above information relates to basic construction requirements and some aspects of the use of trailers. In addition it is recommended that you check whether you have the appropriate Driving Licence entitlement and whether the vehicle or combination of vehicles requires a tachograph to record driver's hours. The latter will apply to most vehicles and combinations of vehicles above 3500kg gross weight, where used for commercial purposes.

Vehicle towing Frequently asked Questions (applicable in the UK)


Towing capacity/weight

1. How can I find out the towing capacity of my car?

A car that has EC Whole Vehicle Type Approval (ECWVTA) will have a Vehicle Identification Number plate (VIN plate) bearing the vehicle manufacturer's name, chassis number and an approval number including the letter "e" in a small rectangle. This plate is usually located under the car's bonnet, but it can sometimes be located in other positions, for example near the driver's door.

The plate will look something like this:

VIN No (This is sometimes called the chassis number and it is unique to that specific vehicle)

XXXX KG (The maximum vehicle weight, e.g. the total weight, it does not include any trailer weight)

XXXX KG (The maximum train weight, vehicle plus trailer)

•  XXXX KG (maximum load front axle)

•  XXXX KG (maximum load rear axle)

So if for example you have a car with a maximum weight of 2180 kg and a train weight of 3980 kg the maximum towing capacity will be 3980 kg minus 2180 kg, which gives a towing capacity of 1800kg

This information may also be found in the vehicle handbook, or from a vehicle specification sheet supplied by the manufacturer.

2. I have a type approved car, but no train weight is shown on the VIN plate, may I still tow with it?

If the manufacturer has not authorised the towing of a trailer by declaration during the type approval process, no train weight will be shown and it is not permitted to fit a coupling device or tow a trailer.

For example the Ford KA has no declared train weight, and no mounting points for a tow bar. There are a number of other vehicles, which do not have a declared train weight and are not able to tow a trailer.

Tow bars /couplings

3. What is a type approved tow bar?

A type approved tow bar is a tow bar, which has been approved to Community Directive 94/20EEC.

4. What are the requirements to fit a type approved tow bar?

If you wish to tow anything with a car, which was first used on or after the 1 August 1998 the car must be fitted with a type approved tow bar.

5. My car was first registered on 1 September 1998; do I need a Type approved tow bar?

Yes, all cars first registered on or after 1 August 1998 must be fitted with a type approved tow bar if they are to be used for towing.

6. How can I tell if a tow bar is type approved?

Each type approved tow bar will have a label, plate, or stamping detailing its type approval number for example E11xxxxxxx, and the details of the vehicle for which it is an approved fitment.

7. May I fit a type approved tow bar myself?

Yes, provided you use the car manufacturer's approved mounting points, and follow the tow bar manufacturer's instructions.

Brakes / Weight

8. What is the maximum weight I can tow with an unbraked trailer?

The maximum you may tow with an unbraked trailer is 750 kg. The towing vehicle must have a kerbside weight at least twice the maximum weight of the trailer..