All vehicles over with a maximum authorised mass over 7.5 tonnes must have markings on the rear of the vehicle. These markings are rectangular and are coloured red and yellow.


Vehicle categories on driving licences can depend on the vehicle’s weight – the different terms you may see are explained below.

Unladen weight

The unladen weight of any vehicle is the vehicle’s weight when it’s not carrying any passengers, goods or other items.

It includes the body and all parts usually used with the vehicle or trailer when used on the road. It doesn’t include the weight of the fuel or if it’s an electric vehicle, the batteries.

Kerbside weight is similar but includes a tank of fuel.

Maximum Authorised Mass

Maximum authorised mass (MAM) means the weight of a vehicle or trailer including the maximum load that can be carried safely when it’s being used on the road.

This is also known as gross vehicle weight (GVW) or permissible maximum weight.

Plating Certificate

The vehicle weight and axle limits will be listed in the owner’s manual and normally shown on a plate or sticker fitted to the vehicle.

This may also show a gross train weight (GTW), also sometimes called gross combination weight (GCW). Which is the total weight of the tractor unit plus trailer and load.


The total weight transmitted to the road by all the wheels on one axle.

The weight of a vehicle and its load.

The weight of a vehicle, a trailer and its load.

Either the design weight limit given on a manufacturer’s plate or the legal weight limit given on the department’s plate.

A trailer pulled by a rigid vehicle.


Vehicles are limited to a maximum of 6 axles, and limited to an overall maximum weight of 44 tonnes


An ‘abnormal load’ is a vehicle that has any of the following:

Projection Markers

A load that projects more than 2 metres to the front or rear of the vehicle must be fitted with an end marker.

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Back Title

Side markers must be displayed if your load is over 2.9 metres (9 feet 5 inches) wide or if the front or rear projection exceeds 3 metres.

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Side Marker


If you’re responsible for transporting an abnormal load, you need to follow regulations for notifying the authorities.

Depending on the load you’re moving and your route, you may need to give advance warning to the police,  highway authorities and bridge and structure owners such as Network Rail

 Vehicles carrying loads between 4.3 metres (14 feet 1 inch) and 5 metres (16 feet 6 inches) wide are subject to lower speed limits. The limit depends on the type of road.


Special Types General Orders or STGOs are a set of regulations that allow unusual vehicles to be driven on UK highways. An STGO will indicate which category a vehicle is licenced to operate within

Examples of vehicles likely to be used under an STGO are:

There are three weight categories of STGOs:

Category 1 – max gross vehicle weight N/A and max category gross weight 50,000kg

Category 2 – D x 7,500kg and max category gross weight 80,000kg

Category 3 – D x 12,500kg and max category gross weight 150,000kg

(where D = the distance in metres between the foremost and rearmost axles of the vehicle carrying the load; or, in the case of articulated vehicles the kingpin and the rearmost axle on the semi-trailer; or, in the case of any other description of combination, the foremost axle and the rearmost axle of the group comprising of all the vehicles in the combination that are carrying a load).

In order for a vehicle to be classed as STGO Cat 1 it must not exceed 46,000kg with a minimum of 5 axles, and 50,000kg with a minimum of 6 axles. In this category the AW regulations minimum weights apply to axle and the vehicle gross weights. All STGO Cat 1 vehicles must display a “STGO Cat 1” plate to the front of the towing vehicle.

Before an STGO Cat 1 vehicle is to be used on the highways a minimum 2 days’ notice must be issued to highways and bridge authorities about the weight. The police may need to be informed of the vehicles’ dimensions.

The speed restrictions enforced for STGO Cat 1 vehicles are maximum 60mph on motorway, maximum 50mph on dual carriageways and a maximum of 40mph on all other roads.

An STGO Category 2 vehicle must not exceed 80,000kg. There are a number of other conditions that apply to the category. Category 2 vehicles must have a minimum of 6 axles, with the combined axle weight not exceeding 12,500kg.

In addition, a vehicle in this category must display the “STGO Cat 2” plate to the front of the towing vehicle. Where an STGO Cat 2 vehicle is to be used, there must be 2 working days’ notice to all relevant highway and bridge authorities. It may also be necessary to inform the police of the dimensions of the vehicle/s.

STGO Cat 2 vehicles are subject to specific speed restrictions. The speed limit on a motorway is 40mph, on a dual carriageway it is 35mph and just 30mph on other roads.

The STGO Cat 2 plate displayed on the vehicle must show the maximum weight recommended by the vehicle manufacturer when travelling at certain speeds. This plate must be marked “Special Types Use” and should show the weights for gross, train and axle weights.

STGO Category 3 vehicles can not exceed 150,000kg. They must have a minimum of 6 axles and have a maximum axle weight of 16,500kg.

It is essential that these vehicles display an STGO Cat 3 plate at the front of the drawing vehicle.

Due to the exceptional size and weight of these Cat 3 vehicles, operators must give at least 5 working days’ notice to highways and bridge authorities and as with Cat 1 and Cat 2 vehicles the dimensions may need to be given to the police.

As you would expect, the speed limits imposed on Cat 3 vehicles are even more restrictive. Motorway speed is limited to 40mph, dual carriageway speed is limited to 35mph and a maximum speed limit of 30mph is enforceable on other roads.

STGO Category 2 and STGO Category 3 vehicles must also be fitted with a plate that shows the maximum weight recommended by the vehicle manufacturer when travelling at certain maximum speeds. This plate must be marked “Special Types Use” and should show the weights for gross and train.

Telephone lines

You should tell telephone companies about your intended route when planning the movement of loads over 5.25 metres (17 feet 6 inches) high.

You should notify them in plenty of time before making the journey.

Electrical cables

Electrical cables spanning public roads should be no less than 5 metres (16 feet 6 inches) unless signage says otherwise


The headroom under bridges in the UK is at least 5 metres (16 feet 6 inches) unless marked otherwise. However, this might refer only to the highest point of an arch.

Bridges less than this will display a sign indicating the height of the bridge. 

If your vehicle hits a bridge, you must report the incident to the police. If a railway bridge is involved, you must also report it to the railway authority quoting the bridge identification number which will be displayed on a sign under or near the bridge


If your vehicle is too long to fit into a passing place, you may need to wait opposite one.

This will allow a following or approaching driver to pass. When you use this type of road, you need to plan and look well ahead to avoid meeting another road user at an inappropriate place.

If your lorry is over 17 metres (55 feet) long and you wish to cross a level crossing, you must stop before the crossing and telephone the signal operator.

Diminishing loads

Drivers should be wary about axle overloads when removing large portions of the load from either the front or the vehicle's rear. The remaining load may need re-distribution to avoid the axles becoming overloaded.