Understand your vehicles’ data plates

Understand your vehicles’ data plates

Commercial vehicle operators and drivers need to understand the information displayed on the data plate affixed to their vehicles. Without this information, it’s impossible to establish the maximum imposed load.

It is a mandatory requirement for all buses, minibuses, goods vehicles, truck tractors and trailers to display certain prescribed information, which must be clearly imprinted or stamped on a metal plate affixed in an accessible position. (Regulation 245 of the Road Traffic Act.)

The purpose of the data plate on a commercial vehicle is to indicate the various permissible and manufacturer’s maximum-load capacities of the vehicle. Failure to adhere to the maximum manufacturer’s specifications could result in the vehicle warranty being rejected and expensive repair costs.      

Failure to adhere to the legal limits could have very serious, costly and dangerous consequences, as well. Remember, ignorance of the law is no excuse.

The metal or aluminium plate must be affixed by the manufacturer of the vehicle; usually on the cab door or under the bonnet. On trailers it can normally be found in a visible position on the kerb side of the trailer.      

To understand these data plates it is necessary to understand the letter symbols shown on the plate. The information is divided into two sections. Normally the first section denotes the manufacturer’s specifications. The second section indicates the maximum permissible loadings, in other words the maximum legal mass of the loads.

The meanings of the symbols illustrated in the first section of a data plate are described below. These are the maximum design limits as set by the vehicle manufacturer.                            

GVM – Gross vehicle mass is the maximum total allowable mass that can be imposed on a vehicle, according to the manufacturers rating. This includes the mass of the chassis cab and the body.                                            

It also includes the payload and any add-on equipment that may be fitted to the vehicle. The GVM rating is set by the manufacturer and may not be exceeded.

GCM – Gross combination mass is the maximum total allowable mass that can be imposed on a vehicle when the vehicle is pulling a trailer.

Again, this includes the total mass of the truck, trailer(s), payload and any add-on equipment.

GA – Gross axle mass is the maximum load that the axle is designed to carry.

GAU – Gross axle unit mass is the maximum load that a tandem or tridem axle is designed to carry.

KW – the power rating of the vehicle in kilowatts.

T – Tare mass is the mass of the empty vehicle ready to travel on the road. This includes the body mass plus any add-on equipment, but excludes fuel and payload.

The meaning of the symbols illustrated in the second section of a data plate is described below. These are maximum legal limits set by the Department of Transport, taking into account the restrictions imposed by the Road Traffic Act. These limits must not be exceeded.

V – The maximum permissible (legal) mass, when fully loaded. This mass must not be exceeded when the vehicle is operating on a public road.

DT – Drawing vehicle’s maximum permissible mass.

A – Permissible axle mass load.

AU – Permissible axle unit mass load.

The information described on the plate allows the owner and driver of the vehicle to establish the exact payload that can be transported legally.

It is important to note that it is illegal for any of the information displayed on the plate to be altered in any way, without the consent and approval of the original manufacturer.


One of this country’s most respected commercial vehicle industry authorities, VIC OLIVER has been in this industry for over 50 years. Before joining the FOCUS team, he spent 15 years with Nissan Diesel (now UD Trucks), 11 years with Busaf and seven years with International.

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Focus on Transport

FOCUS on Transport and Logistics is the oldest and most respected transport and logistics publication in southern Africa.
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