Vehicle Weight and Distribution

Weight Glossary

17th December, 2020 by rvSafe Team
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Are you wondering about your vehicle weight and all associated acronyms? Below is a glossary of all the terms to help you familiarise yourself with vehicle weights; however, make sure you check out our other articles to understand how this applies to your RV.


Tare Weight

Tare weight represents the unladen weight of the vehicle including all engine fluids and a 10L fuel reserve. It is important to note that this may not include dealer inclusions or optional fittings at the time of purchase.

Kerb Weight

Kerb weight is similar to tare weight but with a full tank of fuel and without any accessories.

Tare Trailer Mass

Tare trailer mass represents the unladen weight of a trailer. Unlike a vehicle, it does not include any fluids.


Payload refers to the total weight you can add to your vehicle. This includes fresh and wastewater, gas bottles, personal items, clothes, bedding, food etc. It can also include optional extras and aftermarket modifications such as awnings and driving lights. If you are towing, your tow ball weight must be included in your vehicle’s payload.

You can calculate your caravan or camper trailer payload by subtracting the Tare Mass from the Aggregate Trailer Mass (ATM).

Gross Trailer Mass (GTM)

Gross trailer mass is the tare weight on the axle(s) plus the proportion of the payload acting on the axle(s). This is specified by the manufacturer and is the legal total weight that can be supported by the wheels of a trailer.

Aggregate Trailer Mass (ATM)

Aggregate trailer mass is the maximum total weight of the caravan or camper trailer. This is specified by the manufacturer and includes the tow ball weight.

Gross Vehicle Mass (GVM)

Gross vehicle mass is specified by the manufacturer and is the maximum legal loaded mass of the vehicle. It includes the weight of the car, fuel, vehicle payload, all passengers, plus tow ball weight if towing.

Tow Ball Weight

Tow ball weight, also referred to as tow ball mass, is the weight pushing down on the tow ball by the coupling of the RV being towed.

Gross Combination Mass

Gross combination mass is the total permissible weight of the loaded vehicle and caravan together and is specified by the manufacturer.

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