Towing capacity of a light motor vehicle
The towing capacity of light motor vehicles is restricted by the tare of the towing vehicle when such a trailer is equipped with no brakes or with an inertia/overrun brake system.
However, most, if not all manufacturers of LDV's state GCM and towing capacities way in excess of these limits. Only the fitment of alternative service brake systems will allow the market to utilise the potential full trailer towing.
The legal requirements are as follows:
National Road Traffic Regulations, 2000
151. Brakes on trailers
(1) Subject to the provisions of subregulation (4) no person shall operate on a public road a trailer, if—
(a) the gross vehicle mass of such trailer does not exceed 750 kilograms and the gross vehicle mass—
(i) does not exceed half the tare of the drawing vehicle, unless such trailer is equipped with a parking brake or other device to keep such trailer stationary;
(ii) exceeds half the tare of the drawing vehicle but does not ex-ceed such tare, unless such trailer is equipped with a parking brake and either a service brake or an overrun brake; or
(iii) exceeds the tare of the drawing vehicle, unless such trailer is equipped with a parking brake and a service brake;
(b) the gross vehicle mass of such trailer exceeds 750 kilograms but does not exceed 3 500 kilograms and the gross vehicle mass—
(i) does not exceed the tare of the drawing vehicle, unless such trailer is equipped with a parking brake and either an overrun brake or a service brake; or
(ii) exceeds the tare of the drawing vehicle, unless the trailer is equipped with a parking brake and a service brake;
(c) the gross vehicle mass of the trailer exceeds 3 500 kilograms, unless such trailer is equipped with a parking brake and a service brake, and where more than one trailer is drawn by a drawing vehicle, the foregoing requirements shall apply in respect of each such trailer, and in such event the gross vehicle mass shall be construed as the total of the gross vehicle mass of all trailers so drawn.
[Sub-reg. (1) substituted by r. 42, GNR.1341 w.e.f. 25 September 2003.]
(2) The service brake of a trailer shall be capable of being operated by the driver of the drawing vehicle while such trailer and drawing vehicle are in motion.
(3) If the service or overrun brake of a trailer is capable of being used as a parking brake, a separate parking brake need not be fitted to such trailer.
(4) Notwithstanding subregulation (1) (c), if a trailer referred to in that subregulation is drawn by a tractor and such tractor is not designed for or capable of operation at a speed exceeding 40 kilometres per hour on a reasonably level road, such trailer may be equipped with an overrun brake in lieu of a service brake.
The weight limits for a combination with a drawing vehicle and a category O2 trailers are:
The GVM of such trailer may not exceed the Tare of the drawing vehicle if the trailer is fitted with overrun/inertia brakes
The trailer may not exceed the maximum towing capacity stated by the manufacturer.
The towing vehicle and trailer coupled together may not exceed the GCM stated by the manufacturer. Both vehicles can be in different states of load, i.e. laden towing vehicle and unladen trailer, unladen towing vehicle and laden trailer or any load condition in between.
An assessment of most of the currently marketed LDV's has indicated that in nearly all cases the towing capacity for a braked trailer is considerably higher than the tare of the vehicle, which would then require a service brake system instead of an overrun/inertia brake systems on the trailer.
There is also evidence that trailers with alternative service brake systems are currently being brought into the market and registered.
It would be of great advantage for the industry and the market, if adequate solutions could be discussed to find ways to legalise such brake system installations.
Download towing capacities of LDV's here (pdf)