Payload creep: why your van weighs more than the day you bought it

Eighteen months after I sold the house and hitched up, I put the van over a public weighbridge out the back of a truck stop on the Newell and nearly didn't believe the ticket. Loaded, I was 340 kg over my Aggregate Trailer Mass. Not because I'd bought anything enormous. Because of eighteen months of small, sensible-seeming additions that nobody adds up until the day the ticket comes out heavier than the van.

That's payload creep, and it gets almost every full-timer eventually. The van you bought with a genuine payload of maybe 400-450 kg above tare doesn't stay that way. Every accessory fit-out, every "just in case" item, every second folding chair chips away at a number that was never that generous to begin with.

How the payload actually gets eaten

Start with the number on your compliance plate. Tare weight is the van as it left the factory — empty water tanks, no gas bottles, no battery in some cases, no annexe, nothing. Subtract that from your Aggregate Trailer Mass (ATM) and you get your payload. On a lot of 21-22ft off-road vans that's somewhere between 350 kg and 500 kg. That number has to cover water, gas, food, clothes, tools, spares, batteries if fitted after delivery, awning, chairs, the lot.

Water alone gets you a long way there. Two 95-litre tanks full is 190 kg. Add a 20-litre grey water carry-jerry for dry camps and you're at 210 kg before you've packed a single tin of baked beans. Two 9 kg gas bottles full add another 18 kg-ish including the bottle itself. A second house battery fitted after delivery, if it's a 100Ah lithium, is another 12-14 kg — not much on its own, but it's on top of everything else.

Then it's the stuff that accumulates because you're actually living in the van rather than just holidaying in it. A generator. A second recovery kit because the first one lives in the tow vehicle. An extra 20 litres of diesel in a jerry can for the Tanami or the Gunbarrel Highway where fuel stops are three figures apart. Books. A dog bed. Tools you were sure you'd need once and now can't imagine leaving behind.

Why the compliance plate lies to you (sort of)

I'll be blunt: the tare weight on your plate is close to fictional for how most of us actually use the van after fit-out. Dealers fit solar, extra batteries, annexes and awnings before handover and some of that is included in tare, some isn't — check your specific compliance documentation, because it varies by manufacturer. If you've had any aftermarket work done since — second battery, extra water tank, drawer systems, a bullbar-style stone guard on the front — none of that is reflected in the factory tare figure at all.

This is the bit that catches people. You assume the payload gap is what's printed on the plate. It isn't, not anymore, the moment you've added anything post-delivery. The only way to know your real number is to weigh the van as it sits, loaded the way you actually travel, and compare that reading against the ATM stamped on the compliance plate.

The weighbridge habit that actually works

I get mine done roughly every six months, more often if I've changed something significant — new batteries, a different fridge, an annexe upgrade. Most regional towns have a public weighbridge, often at the produce merchant, saleyards or a transport depot, and the cost is usually somewhere between $40 and $60 for a full set of axle-group readings. Worth every dollar.

What you actually want isn't just a total. You want individual axle group weights for the van and the tow vehicle, plus tow-ball weight if the operator can give it to you separately. A total ATM reading that's under limit can still hide an axle group that's over, particularly on tandem-axle vans where load isn't evenly split front to back. I've written before about the difference in tare and loaded towing behaviour — see loaded weight versus tare — and axle distribution is half of why that difference shows up so clearly on a wet road at 100 km/h.

If you don't have a proper weighbridge nearby, get the van onto bathroom-scale style setups only as a rough sanity check, not as gospel. For tow-ball weight specifically, a proper tow-ball scale or a set of platform scales under the jockey wheel gives you real numbers — bathroom scales genuinely aren't built for it and I've watched people get readings 20-30% out using them.

What actually comes out when you're over

When I found I was 340 kg over, the audit was uncomfortable because nothing I removed felt optional at the time. Here's roughly what left the van, and why.

The second recovery kit went — I kept one comprehensive kit in the tow vehicle rather than duplicating gear across both, which is covered properly in the recovery kit I actually pack. The extra 20 litres of diesel got reduced to 10, because I mapped my actual fuel range against known servo locations rather than carrying for a worst case that rarely happens. Books went to a Kindle. Two folding chairs became one plus a swag-style camp stool. None of it was dramatic. All of it added up.

What I didn't touch was water capacity, because on tracks like the Oodnadatta or heading toward Wilpena Pound in shoulder season, water margin is safety margin, not comfort. If you're going to cut payload, cut consumables you can restock easily, not the ones that get you through country where the next tap might be 200 km away.

Tow-ball weight moves with payload creep too

Here's the part most people miss: as total payload creeps up, tow-ball weight usually creeps up faster if you're loading the front boot or front locker, which is where most of us stash batteries, gas bottles and tools because it's the easiest place to reach. Aim for tow-ball weight somewhere around 8-10% of your actual loaded ATM, not tare. If your van's loaded weight sits at 3200 kg, you want roughly 260-320 kg on the ball, and it needs to be checked with the van loaded as you actually travel, not as it left the showroom.

Too little tow-ball weight and you're in classic sway territory the moment a truck overtakes — I've covered the physics of that properly in understanding caravan sway. Too much and you're loading the tow vehicle's rear axle and steering feel disappears on the front end, particularly noticeable on anything towing near its GVM already.

A number worth checking before you check anything else

If you do nothing else this year, do this: find your nearest public weighbridge, load the van the way you'd actually take it away for a fortnight, and get a full set of readings. Compare that ticket against the compliance plate ATM and GVM for the tow vehicle too — plenty of people are legal on the van and illegal on the tug because the tow vehicle payload gets forgotten in all this.

The National Transport Commission publishes the current heavy vehicle and towing mass rules if you want the source document rather than forum opinion, and it's worth an actual read rather than a skim, because the definitions of ATM, GTM and GCM trip up even experienced tourers.

I check mine every six months now, same as I check tyre pressures before anything remote. Neither habit is exciting. Both have kept me out of trouble on tracks like the Birdsville where the last thing you want is a suspension component giving up 60 km from the nearest town because the van's been carrying 300 kg it was never built to carry.

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