Tow ball weight is the download your trailer places on your vehicle's tow ball. A reasonable starting estimate is ten percent of the trailer's aggregate mass, so 350kg from a 3,500kg van. It counts against your payload, your rear axle and your GVM.
As a starting point, assume the tow ball weight is about ten percent of the trailer's ATM. It is a rule of thumb rather than a law: the real figure depends on where the load sits relative to the trailer's axles, and it changes every time you repack.
Load a heavy toolbox at the front of a trailer and the download climbs. Shift weight behind the axles and it drops, which sounds helpful until the trailer starts to sway. Too little tow ball weight is a stability problem, not a saving.
So use ten percent to plan, and then measure the real number once, with the trailer packed the way you actually travel.
The weight on the ball is pressing down on your vehicle, so it is part of your vehicle's loaded mass. It counts towards GVM exactly like a passenger or a toolbox, and because it is behind the rear axle it lands hard on that axle in particular.
This is the single most commonly missed number in a payload calculation. A ute with 900kg of payload and a 3,500kg van is starting from 550kg once the ball weight is counted, and that is before the driver's mates, the fridge, the water and the recovery gear.
It also has a lever effect. Weight hung behind the rear axle takes load off the front axle while loading the rear, which is why heavily loaded rigs can feel light in the steering.
Most manufacturers publish a maximum tow ball download, commonly 350kg on a ute rated to tow 3,500kg. Some publish nothing at all, and we leave those blank rather than filling in a plausible number.
Your towbar and your hitch have their own ratings, and the lowest rating in the chain is the one that applies. The towbar's rating is on a plate or label on the bar itself.
Here is what each model we hold spec sheets for actually publishes.
| Model | Tow ball max |
|---|---|
| Mazda BT-50 | 350kg |
| Isuzu D-Max | 350kg |
| Mitsubishi Triton | 350kg |
| Volkswagen Amarok | 350kg |
| Nissan Navara | 350kg |
| GWM Cannon | 320 to 350kg |
| LDV T60 Max | 350kg |
| KGM Musso | 350kg |
| Kia Tasman | 350kg |
| BYD Shark 6 | 250 to 350kg |
Current generation only, from the manufacturers' published spec sheets. Ranges cover every variant of that model. On a wider screen there is also the ten percent rule of thumb applied to each model's maximum braked towing capacity, for comparison against the published limit.
No published tow ball limit: Toyota HiLux, Toyota LandCruiser Prado, Ford Ranger, Toyota LandCruiser 79 Series, Toyota LandCruiser 300. We leave those blank rather than assuming the usual 350kg. Your towbar has its own rating, on a plate on the bar.
The cheapest accurate method is a public weighbridge. Weigh the vehicle and trailer as a combination, then weigh the vehicle alone with the trailer unhitched, and the difference tells you what the trailer was contributing through the ball.
There are also purpose-made tow ball scales, which sit under the coupling and give you a direct reading. They cost less than one overload fine and they let you check after every repack rather than once a year.
The bathroom scales and a length of timber trick works well enough to catch a problem, and not well enough to prove you are legal at the margin. If you are within 50kg of a limit, use a weighbridge.
The calculator on this site has a field for tow ball weight, and it applies it to your payload, your GVM and, where the manufacturer publishes axle ratings, your rear axle. Enter your trailer's ATM and start with ten percent if you have not measured yours.
If your rig is close to a limit, the useful next step is a weighbridge ticket rather than a better estimate.
Start at about ten percent of the trailer's aggregate trailer mass, so roughly 350kg on a 3,500kg van. To get the real figure, weigh the combination and then the vehicle alone at a weighbridge, or use a tow ball scale.
Yes. It presses down on the vehicle, so it counts against your payload and your GVM, and it lands mostly on the rear axle. It is the most commonly forgotten item in a payload calculation.
Commonly 350kg on utes rated to tow 3,500kg, but it is set per vehicle and some manufacturers do not publish it at all. The table on this page lists what each model actually publishes.
Yes. Not enough download makes a trailer prone to sway, which is more dangerous than a slightly heavy ball. Aim for the recommended proportion rather than the lowest number you can achieve.
It does, and so does the hitch and the coupling. The lowest rating in the chain applies, and the towbar's rating is on a plate or label on the bar.
Published figures for your exact variant, plus your bar work, canopy, passengers and trailer. No sign-up.