How much will my car tow?
The Law: To make a legal match of your towing vehicle and caravan,you have to know the total permissible braked trailer weight of your tow vehicle. This is the maximum weight your vehicle can tow, set by the manufacturer. It can sometimes be a surprising figure.
Cars which look big and heavy may have a low tow limit. Some people carriers in particular have low limits. If your vehicle has a maximum braked trailer weight of 1500 kgs, the Maximum Technically Permissible Laden Mass (MTPLM) of your caravan must not exceed this figure.
It is irrelevant that the caravan may not be loaded to its maximum, this is figure that is legally permissible. If it is exceeded by 1Kg the outfit will be illegal and insurance will be invalid.
Eighty-Five Percent
This is best practice, if you are inexperienced at towing a caravan. The MTPLM of you caravan should be 85% of the Cars kerbweight (the car, 90% full of fuel, all the fluids needed to run the car, 68Kg for the driver and 7kg of luggage).
If you have a caravan, divide the MTPLM by 85 then multiply by 100 - this will give you the minimum kerb weight of the vehicle.
If you have a car, divide the kerb weight by 100 then multiply by 85, this will give you the caravan's maximum MTPLM to achieve the 85% figure. This figure could be over the manufactures stated total permissible braked trailer weight, this must not be exceeded, even if the 85% rule is applied.
The 85% rule is ideal if it can be achieved.However, it does limit the choice available to you when looking for a caravan, unless you have anything less than a large 4x4.
A caravan with MTPLM of 1300 kgs would need a vehicle with an ex-works weight of 1530 kgs This is a large vehicle with a relatively small caravan.
A more experienced caravanner may go to 100%, providing that the figure does not exceed the total permissible braked trailer weight of the vehicle.
It is not recommended to exceed this figure as an outfit may become unstable.
In Reality...
It won't be very often when the caravan is being towed fully laden with the vehicle in kerbweight state. However it can occur. It is best to load the vehicle and not the caravan as much as possible, in real terms this will get you closer to the 85% figure.
It is also important to load the caravan correctly. Put all the heavy items over the axle, achieve the correct nose weight when possible. Ensure the caravan is level when attached to the vehicle