If no brakes are fitted to a trailer; then 750kgs is the maximum permissible towing capacity.
With regards to tow vehicles, the towbar fitted must not exceed the capacity approved by the vehicle manufacturer. In some cases some additional (strengthening) materials are supplied with the certified towbar as part of the fitting kit.
Remember that towing a trailer or caravan will decrease your vehicle’s acceleration and braking performance. It will also reduce vehicle control and manoeuvrability, while increasing fuel consumption.
Your vehicle’s towing capacity is a factor of its engine size, brakes, weight, transmission, tyres, bearings, chassis, suspension etc.
After taking these variables into account, the vehicle’s manufacturer establishes a recommended towing capacity, which is the legal maximum and must not be exceeded.