Your vehicle has a ‘Trailer Towing Capacity’ (Kgs) and you will be able to find it either on the vehicle plate (may be located inside one of the doors) on in the owner’s manual. The towing capacity (in kgs) is the maximum loaded mass of the caravan or trailer you can legally tow.
In addition your vehicle’s towbar will also have a weight rating (in kgs)- this is normally (but not always) the same as your vehicle’s towing capacity.
Small trailers have a weight rating called the Aggregate Trailer Mass (or ATM) and this is the maximum the trailer or caravan is allowed to weigh – including the mass transferred to the tow vehicle.
So to answer the question – the ATM of the caravan or trailers must not exceed EITHER the Trailer Towing Capacity OR the Towbar Capacity of the tow vehicle.
For a thorough guide on towing please Click here to view the on-line the Towing Guide