Vehicle weights explained
As well as your age, the different vehicle categories on your driving licence tell you what type of vehicle you are able to drive. These categories are also determined 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 water, fuel or accumulators used for the purpose of the supply of power for the propulsion of the vehicle
Maximum Authorised Mass
The term Maximum Authorised Mass (MAM), which is also known as gross weight and permissible maximum weight, is the maximum weight of the vehicle that may be used on the road including the maximum load the vehicle may safely carry. This is normally shown on a plate fitted to the vehicle.
If a vehicle is unlikely to be used at its potential maximum weight most vehicles may be downplated, i.e. the vehicles springs or other components can be changed, so that only a lighter load can be carried. The maximum authorised mass or gross weight is a factor in determining what driving entitlement is required.
Plated weight
The maximum authorised mass should be shown on the departments manufacturing plate fitted to the vehicle. This means the marking on a goods vehicle, by means of a ministry plate, showing the maximum weights for that particular vehicle eg maximum authorised mass, and in certain cases, train weight.
Train weight
Train weight is the combined MAM of the vehicle and the trailer it is pulling.
Further information
All enquiries concerning maximum weights of rigid vehicles, trailers and articulated combinations (but not driving licence categories) should be referred to:
Helpful contacts
Transport, Technology and Standards Department for Transport Zone 2/01 Great Minster House 76 Marsham Street London SW1P 4DR |
Page last updated: 12/04/2007