3.5 tonne rule

The rule to adhere to for most drivers is the 3.5 tonne rule. This outlines the weight ratio limits of towing trailers and caravans.

Category B vehicles are those with a MAM of up to 3.5 tonnes, carrying up to eight passengers. These are allowed to tow a trailer over 750kg as long as the MAM of the trailer does not exceed the unladen weight of the vehicle and the combination does not exceed 3.5 tonnes.

The weight of the trailer cannot exceed the unladen weight of the vehicle towing it.

Otherwise they can tow a trailer weighing less than 750kg, allowing for a combined weight of up to 4.25 tonnes.

Car manufacturers will often specify a maximum weight of trailer suitable for the vehicle.

So for example, a vehicle weighing 1.5 tonnes but with a MAM of 2.25 tonnes can tow a trailer with a MAM of 1.25 tonnes because this combination does not exceed 3.5 tonnes and the weight of the trailer is not greater than the unladen weight of the vehicle. A Saab 9-3 sportwagon towing a Bailey Orion 430-4 would come in at around these weights making it a perfectly legal combination.

An example of a combination that would not be allowed is; a car weighing 2 tonnes with a MAM of 2.75 tonnes towing a caravan with a MAM of 1.75 tonnes. Here the combination exceeds 3.5 tonnes. An outfit combining a Range Rover and a Bailey Unicorn Barcelona would be one example of this.

Likewise, a car with an unladen weight of 1.5 tonnes could not tow a caravan weighing 1.75 tonnes because the weight of the trailer cannot exceed that of the vehicle towing it. For illustrative purposes, an average Ford Mondeo would weigh about 1.5 tonnes and a Swift Challenger 620 comes in with a MAM of just over 1.75 tonnes, meaning this combination would not be legal.

It is important to find out the weight of both your car and caravan to ensure you are road legal.

Remember, it is the MAM of the caravan that matters not its unladen weight.

Applying for the B+E licence

If you passed your test after 1st January 1997 and you believe your current outfit is not road legal you are required to take an additional driving test to gain extensions to your licence.

You will need to apply for a B+E licence, which allows you to tow a trailer weighing over 750kg with a vehicle up to 3.5 tonnes. There is no further theory test but you are required to take a practical test.

With this license there are no limits on the weight ratio of your vehicle and trailer combination, however you cannot tow something which exceeds the weight limits of your towing vehicle.

You should always ensure you’re within the legal weight limits when towing a caravan and that you have the correct towing licence.