Glossary of terms used in this guide
Unladen Weight (UW)
The weight of the trailer (or towing vehicle) less removable optional equipment and
load
Gross Weight
The total weight of the trailer (or towing vehicle) and load Gross Vehicle Weight
(GVW) or Gross Weight Mass (GWM) The total weight of the towing vehicle and its
load
Maximum Gross Weight (MGW)
The maximum figure set by the manufacturer for the gross weight. This will normally
be the technically permissible maximum based on the carrying capacity of the tyres,
axles, coupling, suspension and chassis but may have been adjusted downwards for
commercial reasons
Technically Permissible Maximum Weight
The technically permissible maximum based on the capacity of the tyres, axles, coupling,
suspension and chassis
Maximum Authorised Mass (MAM)
As maximum gross weight above. The latest EC term as used in the Driver Licensing
Regulations
Gross Train Weight (GTW )
The maximum allowable combined weight (combined MAM) of the towing vehicle and trailer
as set by the towing vehicle manufacturer
Payload:
The difference between the gross weight of the trailer and its unladen weight, i.e.
The load carrying capacity
Kerb Weight/Kerbside Weight
The weight of the towing vehicle (without payload), including all fluids required
for operation (95/48/EEC: Vehicle, 90% full tank, 68kg driver and 7kg luggage.)
Vertical Static Load/Nose Load
The weight imposed on the towball or eye by the trailer coupling
Over-run Braking System:
A trailer braking system operated by the action of the trailer bearing on the towing
vehicle under deceleration
Power Operated Braking System
A trailer braking system which is operated directly by the Action of the foot brake
on the towing vehicle
Wheel Track
Horizontal distance between the centre lines of the wheels across the width of the
vehicle or trailer
Wheel Base
Horizontal distance between the centre lines of the wheels of multi-axle vehicles
or trailers along the length of the vehicle or trailer