Check out the towing weight tables we provide per model or your vehicle's handbook for maximum braked and unbraked towing weights. Use these as a guideline. With a fully loaded trailer, braked or unbraked, you must be able to stop from 30km/h on a dry road within seven metres.
Trailer brakes are not required unless total weight exceeds 2000kg. As another guide, don't tow an unbraked trailer which, when fully laden, weighs more than three-quarters of the weight of the tow vehicle.