Tow ball weight. It’s one of those things that gets thrown around a lot in the caravan world, but not always with the right understanding. And here’s the kicker — getting it wrong can seriously affect how your van tows, how your vehicle handles, and whether you’re even legal on the road.
At CHECK WEIGHT, we recently put weighbridges and tow ball scales to the test — and the results were, frankly, shocking. If you rely solely on weighbridge numbers or a cheap tow ball weigher from your local retailer, you could set yourself up for a world of trouble.
Why Tow Ball Weight Matters More Than You Think
Tow ball weight (TBW) is the downward force the front of your caravan puts on the back of your vehicle. Think of it as the anchor that keeps everything stable. Get it wrong, and you’re either too light (hello sway!) or too heavy (goodbye steering and braking performance).
Our general rule of thumb at CHECK WEIGHT is that your tow ball weight should be a minimum of 10–11% of your caravan’s GTM (Gross Trailer Mass) – up to 10% of your caravan’s actual ATM. So, if your van tips the scales at 3000 kg, you want your TBW sitting somewhere around 270–320 kg. That keeps things balanced and safe — especially as your weight shifts with travel. Water tanks fill and empty, food comes and goes, and seasonal packing can sneak extra kilos in without you noticing.
The Dangers of Being Too Light… or Too Heavy
Let’s break it down.
A light tow ball increases the risk of sway. You might feel it kick in at 80–90km/h — your van starts dancing around, and suddenly your steering wheel’s feeling a bit too active. Keep pushing it, and you could be looking at a full-blown sway situation that’s hard to recover from. Worst-case scenario? A jackknife.
A heavy tow ball, on the other hand, can overload your vehicle’s rear axle. That puts extra strain on your suspension, hitch, and tow vehicle. Here’s where it gets sneaky — the added weight on the rear axle also lifts weight off your front axle. Picture a seesaw: add 300kg to the tow ball, and you could be seeing 450 kg extra on the rear axle and losing 150 kg from the front. That’s a serious shift in balance. Add too much weight in the back of your ute and you have a problem.
The result? Sluggish steering reduced braking effectiveness, and poor traction. Ever locked up your front brakes in the wet while towing? This imbalance could be the reason why.
Why Weighbridges Can Get It Wrong
Most people assume a weighbridge is the be-all and end-all. It’s not.
We had a client recently who’d taken his van to a weighbridge. His TBW read 320 kg, putting him over his legal limit of 300 kg. Naturally, he was concerned. But when we measured it using our calibrated TB scale at the correct hitch height — the same height the van is towed at — it came in at 250 kg.
That’s a 70 kg difference, purely based on where and how it was measured. The weighbridge reading had been taken at the jockey wheel at a raised height while unhitched. Not even close to how the van is towed.
Height matters — a lot. We’ve seen 5 kg differences per 25mm of tow ball height, especially on dual axle caravans. Measure too high or too low, and your numbers are off before you’ve even started.
Tow Ball Placement: Hitch vs Jockey Wheel
The location of the measurement also plays a big role. In another test, we measured TBW at the hitch height and again at the jockey wheel, which sat roughly 450mm behind the hitch. The difference in readings? 60 kg.
So, if you’re measuring at the jockey wheel — and especially at an incorrect height — you’re not getting the true picture. That might mean you’re towing either dangerously light or illegally heavy without even realising.
The Problem with Cheap Tow Ball Scales
Now, let’s talk about those cheap tow-ball weighers.
We often let customers compare their gear with our calibrated equipment. One recent session saw three readings taken at the same time, same height, same brand of scale. Ours read 197 kg, the owner’s read 190 kg, and the neighbour’s read 170 kg.
That’s a 30 kg swing, and that kind of inaccuracy can be the difference between legal and illegal, or safe and unsafe. Cheap tools may save you a few bucks upfront, but they could cost you far more in the long run.
The CHECK WEIGHT Difference
At CHECK WEIGHT, we use annually calibrated, NATA-certified equipment that reads to the kilogram. We weigh TBW at the actual tow height, not wherever the jockey wheel happens to be sitting.
We’re not guessing. We’re not rounding. We’re giving you accurate, reliable numbers you can trust — so you can tow safely, legally, and confidently.
Bottom Line? Don’t Leave It to Guesswork
Tow ball weight isn’t something to eyeball. It’s not something to rely on dodgy scales or vague weighbridge numbers for. It’s one of the most important figures in your towing setup — and getting it right could mean the difference between a smooth trip and a nightmare on the highway.
Book a mobile weigh-in with CHECK WEIGHT today. We’ll come to you, measure every angle properly, and make sure you understand exactly where your weights are at — no fluff, just facts.
Jeff Death
CHECK WEIGHT – Mobile Caravan Weighing Australia
Check out our other Blog article on Tow Ball Weight
