Power, fuel economy, payload and towing capacity are the Holy Grail of light truck marketing. However, the value of tow ratings is almost irrelevant in the real world. Let us have a look why.

Three conflicting tow ratings:

From the outset, there are three entirely different tow ratings which you must take into account, as your legal towing limit is the lowest of these three:

• Your vehicle’s towing capacity.
• Your tow bar’s towing capacity.
• Legal limits of your towing capacity based on your driver’s license, towing and towed vehicle type.

 1. Vehicle Towing Capacity

The simple place to find your vehicle’s towing capacity is in your owner’s manual. However, as will be explained below, the stated maximum capacity often differs from what you can actually tow in reality. Before we look at the numbers, there are a few important definitions we must understand.

Tare weight is how much the vehicle weighs, “stock standard”. There is some ambiguity as to the exact definition of ‘stock’, as sometimes (certain manufacturers) it means full of fuel, sometimes partially full, sometimes there’s an allowance for the driver, but it’s basically empty although ready to drive. 

GVM is the maximum the vehicle can legally weigh. This is on the vehicle’s placard and is a definite figure that is readily available for all vehicles. It is often the same for all types of a given model but might vary a bit with trim level, engine or body style. 

Payload is the difference between the GVM and tare weight. For example, if the GVM of a certain bakkie is 3000Kg, and the tare of the bakkie is 2000kg, the payload is (3000-2000=) 1000kg.

However, Payload is everything that is put on the bakkie or that it has to carry. That includes bull bars, roof racks, tow bars, winches, canopies, storage systems, camping gear, recovery gear, occupants and the family Boerbul.

Kitting up your Bakkie may have its advantages but bear in mind the steel replacement bumpers and winches can easily add 200kg onto the vehicle. Then add the canopy and the rooftop tent and pretty soon the vehicle is almost at its GVM. 

This is how much weight can be placed on either axle. Typically, the sum of the two axles is more than the GVM. If we look at the Ford Ranger, the front and rear axles are rated at 1480kg and 1850kg respectively, totaling 3330kg. This is a 130kg more than the 3200kg GVM. This means there’s a bit of flexibility in exactly where the load is positioned over the axles (as some Boerbuls may prefer sitting in the front passenger seat and others in the loadbin).

Braked tow rating is how heavy a trailer the vehicle can tow, provided it has trailer brakes as opposed to no brakes in which case it relies only on the tow car to stop the combination. South African law stipulates that all caravans and trailers with a GVM above 750 kg must be braked.

The braked tow rating is the trailer’s ATM, or Aggregate Trailer Mass. That’s how much the trailer weighs. The Gross Trailer Mass (GTM) is the ATM with the tow ball mass (downforce) subtracted. 

For example, a caravan that weighs 2000kg has a 2000kg ATM, and if there’s 100kg on the tow ball the ATM is 1900kg. The ATM is the trailer equivalent of the GVM. Like vehicles, trailers also have an unladen weight, the kerb weight.

GCM is how heavy the combination of the vehicle and trailer can be. This should be, but isn’t always, the sum of the GVM and braked tow rating (maximum ATM of the trailer).

Now that’s out the way let’s look at some numbers, all in kilograms: 

However, those figures are all in isolation. In real life let’s look how much you can actually tow when going on holiday with a family and the loadbin full. We will start with the GCM of 6000kg and subtract the additional weights.

What comes out is the following:

1) If you want to tow 3500kg, the maximum payload of your vehicle is 6000(GCM)-3500(ATM)-2200(Tare)= 300Kg.  That means you have 300Kg above the stock standard vehicle weight for luggage and occupants and vehicle accessories. I hate to say it, but it seems like you going to have to decide whether its going to be the wife or the Boerbul coming with you on holiday.

2) If you want everyone to come, and you use your 1000kg payload, then the maximum you can tow is 2800kg (as calculated in the table above). This means you’ve lost 700kg or 20% of the advertised maximum towing capacity.

Up until now, the article has been an entirely theoretical exercise focusing on how much you can tow so as not to damage your vehicle. The manufacturer looks at several aspects when calculating the tow rating of their vehicles. These include the strength of the engine, the strength of the transmission, the strength of the axles, the strength of the chassis, the strength of the suspension and the braking power of the vehicle. It goes without saying, and it is something I saw during my time in the tow bar industry, that exceeding the towing limits will damage your vehicle in any or multiple of the areas described above.

Additionally, your safety is important. A recent survey showed that two thirds of accidents involving a towed vehicle resulted from overloading and incorrect loading.

Lastly, there are legal implications to consider if a person has exceeded their allowable towing capacity and causes an accident.

2.     Towbar Towing Capacity

 While O.E tow bars are generally built to match the towing capacity of the host vehicle, this is not always the case. Many aftermarket tow bars save money by building tow bars to a lower spec. For example, while your Ford Ranger can tow 3500Kg, you may find the tow bar itself is only rated to pull 1800kg.

3Always check your tow bar’s rating which will be displayed on the tow bar itself or on the door of your vehicle.

3.    Legal Towing Limits

There are several laws governing what you may and may not tow. Below are a few examples

Ignoring the tow vehicle's mass for the moment, the following maximum trailer mass (GVM) may be towed:
Code B: 750 kg | 750 kg
Code EB: 750 kg | 3 500 kg
Max. unbraked trailer mass (GVM) Max. braked trailer mass (GVM)

The National Traffic Act governs the trailer's maximum allowed GVM as a function of the tow vehicle's tare mass. An unbraked trailer's maximum GVM may not exceed half the tow vehicle's tare mass up to a maximum of 750 kg. Confused? Have a look here:
• 1 000 kg | 500 kg
• 1 500 kg | 750 kg
• 2 000 kg | 750 kg
Tow vehicle's tare mass Max. unbraked trailer mass (GVM)

The maximum GVM of a braked trailer may not exceed the tow vehicle's tare mass up to a maximum of 3 500 kg, as follows:
• 750 kg | 750 kg
• 1 500 kg | 1 500 kg
• 3 500 kg* | 3 500 kg
Tow vehicle's tare mass Max. unbraked trailer mass (GVM)
*B (or EB) licences do not allow driving of a vehicle heavier than 3 500 kg.

In Conclusion

Your safety is of the utmost importance to us. Before going on that well-deserved camping trip, always ensure that both your towing and towed vehicle are fully road worthy, and that you have not exceeded your towing capacity. Remember to always take the lowest capacity of the vehicle rating, the towbar rating and the various gazetted laws.

Here are a few final pointers before you hit the long road:

Insurance claims resulting from accidents while towing may face serious challenges if any of the following apply:

• The tow bar or drop-plate fitted to your tow car by an aftermarket accessory supplier is not SABS-approved.
• You use an approved drop-plate and approved tow bar from an aftermarket accessory supplier, but they have not been approved together as a unit.
• You exceed the maximum drawing capacity of the tow bar.
• You exceed the maximum towing capacity of the tow bar as advertised by the manufacturer.
• The GVM of your overrun-braked caravan or trailer is more than the tare of your tow car.
• The GVM of your unbraked caravan or trailer is more than half the tare of your tow car.

Keep well and drive safe!