Which towing weights must stay within the limit?

GOV.UK's towing weight page, checked in 2026, says most cars have a maximum they can tow, listed in the handbook or specification, and that the gross train weight may be listed on the VIN plate, normally under the bonnet or inside the driver's door. DVSA's safety guidance shows the plate in order: maximum weight of the car on its own, maximum of the car and trailer combined, then the front axle and the rear axle. The combined figure is the train weight. The maximum weight includes passengers, other loads and fuel.

If the VIN plate does not list a train weight, GOV.UK says you should not use the vehicle for towing. Do not invent a train weight from the car MAM plus 3,500 kg. Category BE is a licence cap on the trailer, not a substitute plate. Highway Code rule 98 says you should not tow a weight greater than the manufacturer recommends, and you must not overload the vehicle or trailer.

MAM is maximum authorised mass: the most that vehicle or trailer may weigh when loaded. Towing capacity is the manufacturer's limit for what the car may pull, often a braked figure and a lower unbraked figure in the handbook. Gross train weight is the most the fully loaded car plus fully loaded trailer may weigh together. A legal tow has to sit inside all three, plus the licence.

People add the car MAM to the trailer MAM and compare that with the train weight. That is the right comparison for a fully loaded combination. If you travel with a light car and a heavy caravan, the actual weights can still exceed the train weight even when each MAM looks comfortable on its own. Weigh the combination if you are close. Guessing from the brochure is how a 50 kg overage happens.

The maximum trailer width for any towing vehicle is 2.55 metres. If the towing vehicle's MAM is 3,500 kg or less, you cannot tow a trailer longer than 7 metres. Those lengths do not include the A-frame, the frame that connects the car to the trailer. If the vehicle MAM is more than 3,500 kg, GOV.UK publishes 12 metres for the trailer, 18 metres for the vehicle and trailer combined, and 3.05 metres for how far the load can overhang the back of the trailer.

A caravan that is wider than the car also triggers the towing mirror rule. Width is not only a plate figure. It is a view of the road behind you. Rule 98 says if the vehicle is narrower than the trailer or load, or the trailer obstructs the rearward view, towing mirrors must be used.

Find the car VIN plate, the trailer or caravan plate, and the handbook towing limit. Write down four numbers: car MAM, train weight, trailer MAM, handbook towing limit. Then estimate the actual load: people, fuel, water, gas, kit. Actual loaded car plus actual loaded trailer must stay inside the train weight. Actual loaded trailer must stay inside trailer MAM, and if there are no brakes it must stay at or under 750 kg.

Axle weights on the VIN plate still apply. A rear axle can be over even when the train weight looks fine, if the nose weight is too high or the boot is packed over the hitch. Rule 98 says to distribute weight evenly with heavy items over the axle and a downward load on the tow ball, without exceeding the manufacturer's tow ball load.

Rule 98 says you must not overload. Construction and Use regulation 100 is the Highway Code's cited law for a vehicle in a dangerous condition, and GOV.UK's equipment page publishes a fine of up to £2,500, a ban and 3 points for that. A prohibition can stop the combination until weight comes off. Weighbridges exist for a reason. Arguing that the caravan MAM fitted the licence does not help if the train weight is the figure you passed.

Insurance can treat an overloaded combination as a breach. The MOT on the car does not weigh the caravan. The caravan may have its own periodic inspection depending on use. None of that is a substitute for the plate on the day you hitch.

The VIN plate and the GOV.UK width and length figures are GB towing-with-a-car rules. They apply on GB roads. Northern Ireland has its own construction and use rules. A GB car towed combination in NI still has a VIN plate. Use nidirect for NI-specific trailer construction questions.

A foreign car used in Great Britain still has a manufacturer's plate. If that plate has no train weight in a form you can read, GOV.UK's instruction is not to tow. Do not guess a European plate code into a UK train weight.

That 85 per cent of the car's kerbweight is the law. It is a Club and manufacturer comfort figure, not a GOV.UK legal limit. The legal limits are MAM, train weight, towing capacity and the licence. That the nose weight is optional. Rule 98 requires a downward load on the tow ball within the manufacturer's limit. That water and gas do not count. They count. They are load.

That a braked 1,500 kg caravan is always fine behind a small crossover because BE says 3,500 kg. The crossover's train weight may be 2,800 kg. That is the end of the discussion. Weigh, or load well under, or hire a car that is plated for the van.