Towing capacity: the four limits, and a calculator that checks them

The four limits

1. Braked towing capacity. The most the trailer may weigh, fully loaded (its ATM), if it has brakes. Unbraked trailers have a much lower limit, often 750 kg.
2. Tow ball download. The most weight the trailer may put on the tow ball. Many utes are rated at 350 kg, some less; the towbar has its own rating too, and the lower one applies.
3. GVM (gross vehicle mass). The most the vehicle may weigh, loaded: kerb weight plus people, gear, accessories, fuel and the tow ball weight.
4. GCM (gross combination mass). The most the vehicle and trailer may weigh together.

How to calculate it yourself

• Vehicle weight = kerb weight + people + gear + accessories (towbar, canopy, bar work) + tow ball weight. Must be under GVM.
• Combined weight = kerb weight + people + gear + accessories + the trailer's loaded weight. Must be under GCM.
• Trailer loaded weight must be under the braked towing capacity, and the ball weight under the ball rating.

Best of all, weigh the loaded rig on a public weighbridge, vehicle and trailer separately and together.

Popular tow vehicles at a glance

The last column is the one most people miss: how much the vehicle can carry while towing its full rated trailer. It is often a few hundred kilos, before you add a canopy, bar work or a second battery.

Vans

Our vehicle list covers utes and 4WDs, the most common tow vehicles for caravans. For vans such as the HiAce and Transit, use the same four checks with the figures from your compliance plate and handbook.

Unbraked trailers

A trailer without its own brakes can only weigh a small amount when loaded. Under the national rules, an unbraked trailer may weigh no more than 750 kg loaded, and some vehicles have a lower unbraked limit set by the maker; check your handbook. Most box trailers are unbraked; caravans and boat trailers over 750 kg must have brakes.

Braked trailers and the brake rules

Trailers over 750 kg need brakes. Above 2,000 kg the brakes must work on all wheels, be operable from the driver's seat, and the trailer needs a breakaway system. That means electric or electric-over-hydraulic brakes and a brake controller in the tow vehicle for most caravans. See electric brake controllers.

Why the badge figure is not the whole story

Car makers advertise the braked towing capacity, often 3,500 kg for dual-cab utes. But that figure assumes the vehicle is otherwise lightly loaded. Once you add people, a canopy, a bull bar, a fridge and the tow ball weight, the GVM and GCM limits often stop you towing the full 3,500 kg legally. Plan your trailer around the payload you need, not the brochure number.

Weighing your rig

1. Load the vehicle and trailer as you will travel, with full water and fuel.
2. At a public weighbridge, weigh the vehicle alone with the trailer still attached but only the vehicle on the plate.
3. Weigh the whole combination.
4. Weigh the trailer alone, uncoupled, on its jockey wheel and axles.
5. Measure tow ball weight with a tow ball scale.

Compare each figure with the limits on your compliance plates. Many weighbridges give a ticket for a small fee.

Licences

A standard car licence lets you drive a vehicle with a GVM up to 4,500 kg and tow a trailer. Heavier vehicles need a higher licence class. Some states have restrictions for learner and provisional drivers towing, so check the rules where you live.

Speed, distance and safety

Towing changes how a vehicle behaves. Stopping distances are longer, overtaking takes far longer, and crosswinds and passing trucks can push a caravan. Leave a bigger gap, brake earlier, keep left on highways, and take breaks. In many states, the speed limit for towing is the posted limit, but some vehicles and trailers have lower maker limits.

Towing capacity for vans

Vans such as the Toyota HiAce, Ford Transit and Renault Trafic are popular for work and conversions, and many can tow a trailer. Their towing capacity, GVM and GCM vary by model and body length, and a fully fitted-out van or camper conversion may already be near its GVM before it tows anything. Weigh the van with its fit-out before choosing a trailer, and check the four limits with the figures on its compliance plate and in its handbook.

Before you buy a trailer or caravan

Check your vehicle's four limits first, then look at the trailer's ATM, not just its tare. Ask the seller for the tow ball weight when loaded, and leave a margin for water, gear and future accessories.

The calculator on this page

Enter your vehicle and your trailer's loaded weight, ball weight and the weight of people and gear in the vehicle. The calculator checks each of the four limits and shows which, if any, you exceed and by how much. It is a planning tool: always confirm with your own compliance plates and a weighbridge.

Towing capacity and the tow vehicle's weight

A useful guide many experienced caravanners follow is to keep the loaded trailer lighter than the loaded tow vehicle where possible. A trailer much heavier than the vehicle pulling it has more ability to push the vehicle around in emergency braking or in a crosswind. This is guidance, not a legal limit: the legal limits are the four on this page. But it is a sensible way to choose between two vans, or to decide whether a vehicle is a good match for a heavy trailer even if the numbers say it is allowed.

Electric vehicles and towing

Some electric utes and SUVs now have towing ratings similar to diesel utes. The same four limits apply. Towing a heavy trailer cuts an electric vehicle's range dramatically, so plan charging stops carefully and check that chargers can be reached with a trailer attached, because many charging bays are not designed for vehicles with trailers.

Trailer tyres and towing

Trailer and caravan tyres need the right load rating and pressure for the trailer's ATM. Under-inflated trailer tyres overheat and fail, especially on long, hot highway runs. Check pressures cold before each trip, carry a spare that fits, and replace trailer tyres by age as well as tread, because trailers that sit for months can have old tyres with plenty of tread left.

Common questions