You must also ascertain the maximum towball mass of the vehicle ( often referred to as the TBM ). The TBM is also stipulated by the vehicle ’ s manufacturer . If your vehicle ’ s towbar was fitted by the factory or dealer , it will probably contain a placard identifying the maximum weight it can support , as well as the vehicle ’ s overall towing capacity .
The towbars of reputable aftermarket suppliers such as Hayman Reese will likely have a similar placard .
THE CARAVAN
A caravan ’ s compliance plate comes with a couple of weights ( Tare and unladen ball mass ) and some ratings , too ( Aggregate Trailer Mass and Gross Trailer Mass ).
So which of these do you need to understand ? Ideally , all of them . But to get started , it is important to wrap your mind around Aggregate Trailer Mass ( ATM ) and ball weight .
ATM is the total permissible weight of the caravan , unhitched and supported by the jockey wheel . The caravan must never weigh more than this rating – so it ’ s important to pack carefully . Everything you load into the van , including the water in the tanks and gas in the cylinders , is considered ‘ payload ’. Aftermarket accessories are considered payload , too .
The payload capacity – i . e ., the combined weight of everything you pack in or on the van – is calculated as the difference between the ATM rating and the Tare weight .
A typical compliance plate found in the front boot of a caravan .
Ball weight will rise or decrease in direct proportion to the weight of your gear and where you pack it .
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