How do I work out the maximum towing weight?
The maximum towing weight is a specific weight per vehicle, and is usually stamped on the Vehicle Identification Number Plate (VIN Plate). These are usually an alloy plate, although some are stickers, and a commonly located on the door pillars, or under the bonnet. The details are also available in the vehicle handbook.
Once located, the VIN usually shows 3 or 4 weights that you can use to calculate your maximum towing weight. The first is usually the Maximum Allowable Mass (MAM) which is the gross vehicle weight when full of occupants, fuel and payload. The following number will be the gross train weight, which is the combined (MAM) of the vehicle and a trailer. The next number is the maximum axle load for the front and the final number is the maximum axle load for the rear.
To calculate your maximum towing weight, you’ll need to subtract the gross vehicle weight from the gross train weight.
It is important to remember, not all vehicles are permitted by the manufacturers to have a tow bar fitted, for the purposes of towing. Some (EVs and hybrids) only permit the fitment of a tow bar for cycle rack purposes only. As the onboard electronics and systems are not set up for towing trailers. It is vital to remember this when purchasing a second hand vehicle with a tow bar already fitted, as you will not know if this has been fitted just for a cycle rack, and could cause considerable damage to your vehicle if used for towing.
Although there is a maximum weight, this does not account for height and when you add the height of a caravan the maximum weight will be lower. As a general rule of thumb, the 85% rule should apply. There are some good websites for working this out, including The Caravan and Motorhome Club.