What is the towing capacity
Towing capacity is a measure describing the upper limit to the weight of a trailer a vehicle can tow. In the United States, towing capacity is expressed in pounds, while other countries express the limit in kilograms. Some countries demand that trucks and buses have the maximum trailer weight and eventually maximum trailer length signed close to the coupling device, while this is rare with smaller cars or pickup trucks.
In most european countries new vehicles have it printed on a plate on the vehicles towbar in Kg. If an older vehicle is fitted with a towbar the manufacturer of the towbar is required to calculate the towing capacity of the vehicle and put a plate on it. The calculation for towing capacity can not be covered in this forum as it is a long complex calculation with over 15 different parameters. Refer to an expert - Don' know don't tow.