Vehicle categories on driving licences can depend on the weight of the vehicle – the different terms you might see are explained below.

Unladen weight

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

It includes the body and all parts normally used with the vehicle or trailer when it’s used on a road.

It doesn’t include the weight of:

  • fuel
  • batteries
  • 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.

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), also sometimes called gross combination weight (GCW). This is the total weight of the tractor unit plus trailer plus load.


If a vehicle is unlikely to be used at its potential maximum weight, it may be ‘down-plated’. This means that a lower weight is shown on the plate or sticker attached to the vehicle.