Why caravan Tare weight is important

If you're confused about what caravan Tare mass means, you're not alone!

It’s the most misunderstood weight when it comes to trying to keep your van from being overweight, illegal and dangerous to tow... mainly because it has no direct bearing on any of these things.

Tare basics

Tare basically means how much your van weighs with nothing in it. But how 'empty' does the van have to be, and what is ‘nothing’?

Let’s go to the source of everything to do with trailer standards and requirements in Australia: Vehicle Standards Bulletin 1 (VSB1).

All new trailers (including caravans) either built in or imported into Australia (including used imported trailers) must adhere to the standards outlined in VSB1. If there's a definition of Tare worth knowing, it’ll be here.

But reading the rules, you soon discover that Tare is not one of these critical ‘standards’ that will cause trouble if not complied with, in the way Aggregate Trailer Mass (ATM) and Gross Trailer Mass (GTM) do, for example.

Tare does get a definition in VSB1 though. It’s under section 12.7, where it says: ”Tare is the total mass of the trailer when not carrying any load, but when ready for service, unoccupied (if relevant) and with all fluid reservoirs (if fitted) filled to nominal capacity except for fuel, which shall be 10 litres only, and with all standard equipment and any options fitted. This includes any mass imposed onto the drawing vehicle when the combination vehicle is resting on a horizontal supporting plane. (Fluid reservoirs do not include water tanks and waste water tanks fitted to caravans).”

Because there are a few areas above ripe for mis-interpretation, I asked the media section of the Department of Infrastructure -Regional Development and Cities to seek a clarification of what this all means.

For starters, they confirmed what fluids were, and were not, included in Tare: “For a caravan, this would mean the mass of fresh, grey and black water tanks would not be included in Tare mass, nor the mass of gas in gas cylinders; however if the vehicle had a hydraulic brake system, the mass of the hydraulic fluid would be taken into consideration.”

So whatever you put in gas bottles or water tanks is payload, pure and simple. That can end up being a lot of weight. For example, if you have a large caravan with two fresh water tanks and one grey tank, each containing 95 litres, you have 285kg of payload right there (assuming you’ve forgotten to dump from the grey water tank and it’s brimming full).

What is 'ready for service'?

The part of the Tare definition that really seems to trip everyone up is, “…when ready for service”. What does that mean?

According to the DIRDC, and I quote: “‘Ready for service’ means the trailer is complete to a sufficient extent to perform its intended function.  For a caravan, this means a person would be able to tow the trailer and use it as a caravan with the necessary cooking facilities and accommodation.”

But it's still not 100 per cent clear, because at what point is a caravan ready to a “sufficient extent”?

The Feds went on to clarify: “Standard equipment will include, for example, a spare tyre or gas cylinders.  Options would be dependent on what things are fitted by the manufacturer and what are fitted by a dealer.  If the options are included by the manufacturer, they would be included in the manufacturer’s Tare mass.”

So Tare, according to the body that decides vehicle technical requirements in Australia, is the caravan and options as fitted by the manufacturer.

It's logical that the manufacturer is responsible for the Tare mass figure, not the dealer, as the manufacturer is responsible for the rest of the information on the Trailer Plate.

It gets awfully messy having the detailer out in the dealer’s wash bay inscribing the final Tare mass on the Trailer Plate in a shaky hand after a customer’s five-jerry holder has been weighed and fitted to the back of their new van...

Related:
Overweight caravan epidemic spreads
The truth about overweight caravans
Overweight utes threaten road safety

Big brands weigh at factory

Most major caravan manufacturers see Tare as measured at the factory too. When we asked Jayco, Concept/Newlands/Franklin and New Age, they all responded that all their caravans are weighed at the factory after completion on a certified weight scale, and that this mass is inscribed on the trailer plate before the caravan leaves the factory.

But if you read that Tare is the mass of the new van with every option fitted and as handed over to the owner, that’s okay too. That’s because Tare has no legal ramifications; it can be anything you say it is.

You can’t be fined for a caravan that is under or over Tare (unless it bumps over ATM). You’ll never be pulled over and have a police officer demand you dump everything out of your van to see if you’ve got a legal Tare.

What's more, an RV manufacturer can’t be fined for not including Tare on a trailer plate. The only mass the trailer plate must include is Aggregate Trailer Mass (ATM).

When Tare can be a safety issue

So Tare, by itself, is not a safety concern. Although sometimes it feels it isn’t far off being one.

There have been a couple of instances where I have taken a bone-dry caravan (I emptied the tanks) over a public weighbridge to discover they have been a few hundred kilograms over the plated Tare weight.

Sure, I didn’t empty the gas cylinders or hot water service, but that’ll account for around 35kg, not 200kg. So what's happening here?

If it was a wholesale problem (I have heard plenty of such stories) would it lead to the caravan industry’s very own Diesel-gate? Could 2019 be remembered as the year of Tare-gate?

Not a chance. There is no recourse under the Motor Vehicle Standards Act, and no penalty for manufacturers who inscribe or stamp an incorrect Tare on the trailer plate.

As I said; as it isn’t a safety issue those responsible for setting (safety) standards can’t make measured Tare enforceable.

That doesn’t mean that manufacturers should not wake up and get serious about weights. Of course they should.

Different measurement methods

There are rumours that some manufacturers simply weigh one van and apply the same weight to all subsequent vans of the same specification. And there's nothing stopping them from going one step further — not weighing any of their caravans at all, ever.

According to the Department: “If the manufacturer has systems and information to allow them to calculate the Tare mass of the trailer based on the trailer’s design, it would be acceptable for the calculated value to be used”.

There are also other factors, like the industry insiders who’ve told us that there can be as much as 200kg difference in mass between two identical hot-dipped galvanised chassis. The amounts of the gal liquid drained out after the ‘bath’ are not identical. Clearly.

However, the Feds are interested in having another look at Tare. The Department “is currently consulting on matters related to light trailer manufacture, including Tare mass.  The Department hopes to have a draft of a revised Vehicle Standards Bulletin 1 (VSB 1) document out for public comment in the next few months. To date the consultation has raised some concerns with the definition of Tare mass, which the Department will seek to resolve in consultation with industry.”

That’s all good and well, but it's hard to see how revisions to a safety technical bulletin (VSB1) can solve what is effectively a consumer problem.

That’s because the main problem is not really Tare, or its definition. The industry needs another mass that actually means something to a consumer.

Most caravanners want to know what their payload is, or what weight they can throw into the van and stay on the legal side of ATM, pure and simple.

The only way of knowing that is to subtract the (real) weight of the van before you put in any of your own gear from the maximum weight the van is allowed to weigh (ATM).

Are caravan payloads realistic?

The clincher is that the payload has to be a realistic amount.

And that’s perhaps the direction the industry should take — something as simple as ‘starting weight’ should be quoted; the exact, measured and certified weight of a caravan all gassed and watered and ready to be loaded with your food, clothes and incidentals.

The latter? That’s your payload, and your responsibility. The big stuff has already been accounted for. After all, who always tows with empty gas bottles? And who always tows with empty or half-empty water tanks? If you do, well, you're probably in the minority.

Even when ticking the options, the main ones should be weighed and quoted on brochures so you know if you go for the washing machine, you’ll see exactly how much (up to 45-50kg) it will add to your van’s Tare.

Done this way, the old Caravan Industry Association recommendation of 300kg payload for single axles and 400kg for tandems might finally make sense again. Right now, for larger off-road vans with their multiple tanks and large cargo storage areas begging to be used, they are nonsensically low.

Final word on Tare

So if there is nothing in the standards that can enforce Tare, what can you do about it?

If you already own a van, make sure it is not over ATM, when fully loaded. If it is, then you’ll have to go through the painful process of taking out your payload, and seeing what you’re left with and what might need to be permanently jettisoned, in terms of jerry holders, water tanks or washing machines. That's not a position you want to be in.

If you're buying a new van, make it part of the contract that you won’t take possession of the van or pay the balance for it until you have see an official weighbridge certificate to show it is as per the trailer plate.

It might seem extreme, but until consumer standards are respected broadly across the industry, as a new caravan buyer, it’s what you have to do.

This article was first published in March 2019