Re: tow bar horse box
No unbraked trailer is allowed to have a plated gross vehicle weight* of more than 750 kg. No unbraked trailer is allowed to have a plated gross vehicle weight that is more than half the kerb weight of the vehicle that is towing it.
*The combined weight of the trailer and the maximum amount of cargo it is designed to carry.
Although trailers with overrun brakes can weigh up to 3500kg gross, actual maximum weights are set by the specifications of the vehicle that is doing the towing. The law says you must not exceed the Gross Train Weight that the manufacturer has set for the towing vehicle. Look in the vehilce handbook or on a plate riveted to the vehicle to find this figure. You then have to subtract the weight of the towing vehicle (including fuel, driver, passengers, luggage or cargo) from the Gross Train Weight. The amount you are left with is the maximum theoretically-possible weight of trailer that can be towed legally. REMEMBER, the law does not care whether the trailer is empty or packed to the roof with bricks, what counts is the plated gross vehicle weight of the trailer."