Trailer & Towing FAQs

Every vehicle manufacturer has to give a maximum towing limit. This can be found in the vehicle handbook and also on the chassis plate, usually found under the bonnet.

The information can be presented in a variety of ways. The clearest is when the plate gives the towing limits for both braked and unbraked trailers.

Sometimes the car’s Gross Train Weight (GTW) is given. This is the combination of the car’s Maximum Permitted weight (MPW) sometimes called Gross Vehicle Weight (GVW) and the trailers Gross Trailer Weight. To get the towing limit simply deduct the MPW from the GTW. It is an offence to exceed the car’s towing limit.

The VIN plate will display either 3 or 4 sets of weights, it is these weights that VOSA or the other vehicle authorities use to determine whether your vehicle is towing or being driven within the law.

  • The top figure ‘A’ is the gross vehicle weight, the Maximum Allowable Mass (MAM) of the vehicle including occupants, fuel and payload.
  • The second figure ‘B’ is the gross train weight, this is the combined maximum allowable mass of the vehicle and trailer.
  • The third and fourth figures ‘C’ and ‘D’ are maximum axle loads front and rear respectively.

The manufacturer’s recommended maximum towing capacity for your vehicle is the gross vehicle weight subtracted from gross train weight. (4200kg – 2505kg = 1695Kg)

This calculation is based on a fully laden vehicle.


Certain performance, hybrid and city-car models or similar variants of standard models are not homologated to tow, this means that the vehicle manufacturer has deemed that the model is unsuitable for use as a tow vehicle. With this type of vehicle, the towing capacity will equate to zero or a gross train weight will not be displayed.

What will change later in 2021

If you passed your car driving test from 1 January 1997, you’ll be allowed to tow trailers up to 3,500kg MAM when the law changes.

DVLA will update your driving licence record to show that you’re allowed to tow trailers. You’ll get category BE added to your driving licence when you get a new photocard driving licence.

You do not need to contact DVLA for this to happen. It will be done automatically.

Keep up to date with all the changes HERE

The usual definition of kerb weight is a vehicle in its ready to use condition with all tools, spare wheel etc. and a full tank of fuel. Many vehicle manufacturers are, however, now following European Directive 95/48/EC which specifies the kerb weight as a car in ready to drive condition with the fuel tank 90% full, a driver on board weighing 68 kg and luggage of 7 kg.

Any extras or accessories fitted after purchase will increase the weight and reduce both payload capacity and hence the towing limit. When looking at a car’s specification in a brochure please check the method of determining the kerb weight.

If it is to the EC Directive you must allow for the weight of any other passengers and luggage and deduct that weight from the towing limit accordingly. This could easily reduce the towing limit by 250-300 kg.

If in doubt please check with the car makers technical department directly. Do not rely on a car dealer’s salesman, as they are often uncertain on towing information.

It has certainly been a problem getting insurance for trailers. The NTTA now have a trailer insurance policy to rectify this situation.

The cost of the annual premium is one of the most completive on the market with the minimum annual premium being only £89.00 including Insurance Premium Tax at 5%.

This is for a comprehensive policy with "new for old" for the first three years for new trailers, European use cover for 30 days and replacement hire.

Furthermore, the annual premium is discounted by 20% if the trailer is protected by a Datatag anti-theft device.

To get cover please visit our Trailer Insurance page. The NTTA website allows you to obtain an instant quotation and arrange immediate cover or if you wish ring on 0845 094 8255 to speak to one of our advisers.

You can tow a maximum of 750 Kg with an unbraked trailer but you cannot exceed half the kerb weight of the towing vehicle.

You can tow a trailer with a Gross Weight higher than your car’s towing limit as long as you only load it up to that limit.

It is illegal to exceed the car’s towing limit.

For 1999 model year caravans there was a change in the wiring and pin 7 on the 12S socket is now an earth return for pin 6 - the power supply for the fridge. Your car wiring will not have pin 7 connected.

You will simply require an earth connected to pin 7. Connect this earth to a separate point on the car from that used for pin 3.

Under no circumstance connect the earth on pin 7 with the earth on pin 3 as you can cause a pin to burn out.

The 85% figure is a recommendation, not a legal limit, given by all caravan clubs to give good power to weight ratio for successful towing.

You can legally tow up to the car manufacturer’s towing limit. This may be in excess of 100%.

All cars sold here from the 1st August 1998 must be European Whole Vehicle Type Approved. The vehicle maker decides when he applies for approval if the car will be allowed to tow and the car has towbar mounting points built in to the chassis.

The Ka does not have towbar mounting points so a towbar cannot be fitted. It would be illegal to fit one.

There are a number of other cars that cannot have towbars fitted so if you intend to tow with a small car ask before buying.