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Tuesday, 2 October 2023

Vehicle weights explained

As well as your age, the different vehicle categories on your driving licence tell you what type of vehicles you are able to drive. These categories are also set by the weight of the vehicle.

Unladen weight

The unladen weight of any vehicle is the vehicles own weight when not carrying any goods or burden. This is:

  • inclusive of the body and all parts which are necessary to or ordinarily used with the vehicle or trailer when working on a road
  • exclusive of fuel and, in the case of an electrically powered vehicle, the batteries

Maximum authorised mass

The term maximum authorised mass (MAM), used in the context of driving licences, is the maximum weight of a vehicle or trailer including the maximum load that can be carried safely while used on the road. This is also known as gross vehicle weight (GVW) or permissible maximum weight. It will be listed in the owner’s manual and is normally shown on a plate or sticker fitted to the vehicle. The plate or sticker may also show a gross train weight (GTW).


If a vehicle is unlikely to be used at its potential maximum weight, it may be down-plated, so that a lower weight is specified on the plate. In the case of a heavy goods vehicle, the Vehicle and Operator Services Agency (VOSA) should be consulted because VOSA issue the ministry plate that must be carried on the vehicle. For other vehicles, the manufacturer should be contacted.

Maximum Weights

The maximum weights at which vehicles, trailers and articulated combinations can be used are marked on the vehicle’s plate or ministry plating certificate, and can be found in the owners manual. On some vehicles the maximum weights may also be listed on the vehicle registration certificate (V5C). If in any doubt, the vehicle or trailer manufacturer should be contacted.

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