Every single vehicle in Australia comes with a number of limitations, that are expressed in the vehicles owners manual. Things like towing capacity, gross vehicle mass, fuel capacity and so forth are common, and so is your tow ball weight capacity.
What is tow ball weight capacity?
Put simply, this is the amount of weight that your tow ball can receive, as specified by the manufacturer of the vehicle, or the tow bar and hitch manufacturer, or an external engineer that overrides the original figures.
The tow ball weight capacity of your vehicle will be determined by the lowest value applied. For example, if you have a vehicle rated to 350kg tow ball weight but the tow bar, or tow tongue is only rated to 100kg then that is the limitation.
If you want to know more, we have a comprehensive post on tow ball weight that you can read.
It’s also important to think about how the tow hitch matches the tow bar. For example, running a tow bar extension would likely reduce the tow bars load rating.
What’s the normal tow ball weight capacity?
Most 4WD’s today are rated to take 350kg on the tow ball. That means you are legally allowed to apply up to 350kg on the tow ball.
However, you may or may not be able to get to that as your tow ball weight comes out of your payload (or off your GVM), and with leverage applies around 500kg to the rear axle weight.
However, some 4WD’s are limited to 300kg, and then there are plenty of different anomolies around the place. The earlier Mitsubishi Pajero’s are capped at 180kg if you are towing over 2500kg, and 250kg if you are towing under 2500kg.
Some Nissan Patrols have a penalty rating that is added when you are towing with a heavy tow ball weight, and it all comes down to the engineers wanting the vehicle to be safe, and capable of doing what ever they rate it to.
Ultimately, you’ll find the tow ball weight rating in your owners manual, and sometimes on the hitch (although this needs to match your vehicle, or its the lower of the ratings).
How to increase tow ball weight capacity
There are actually a few ways to increase your tow ball weight capacity.
The first thing you need to check is whether the tow ball weight capacity is equal all the way through. Your tow tongue and tow bar will have a rating, and this should be the same as the vehicle rating.
Sometimes lesser rated tow bars or tongues are fitted, and to increase the tow ball weight capacity all you have to do is fit a different tow bar and tongue.
From there, a couple of specific options exist for increasing the factory tow ball weight capacity. There are kits for the Mitsubishi Pajero to remove the 180kg limitation, just by replacing springs and fitting new rear springs, shock absorbers and air bags, and getting it certified.
You should know that this is rare though, and depending on what state you are in you may find it isn’t possible.
Before you proceed with a tow ball weight capacity increase, look very carefully at your other weights as well, because its incredibly easy to go over one or more of them!
So, if you are looking to increase your tow ball capacity its really a model specific thing. My advice is to consult the tow bar and tongue first, then your owners manual, and then GVM and GCM upgrade businesses to see what they offer.
You might get lucky and be able to tweak it a little, or more than likely you won’t be able to do anything. If that is the case, you either need to loose some tow ball weight, or look for a different tow vehicle.