<span class="highlight">Caravan</span> weights

ATM is Tare plus Payload only!

Hi,
ATM: ATM refers to the weight of a Caravan with its full load when not connected to a tow vehicle = Aggregate Total Mass.
GTM: GTM is also the total weight of the Caravan with its full load, but this measurement refers to the weight of the Caravan when it is attached to the tow vehicle, and will be lower because the tow vehicle absorbs some of the weight (ie the ball load) = Gross total Mass
Ball Load: This is the weight that the Caravan places on the vehicles tow ball.
Now that you have all the weights right for the van are you still within your Tow Vehicle specifications? Your GTM of the Tow Vehicle reduces as you transfer weight from Van onto tow ball, so if your ball weight is 220kg that has to be deducted from the ATM of the tow vehicle.
To get the ATM of van it needs to be disconnected from tow vehicle at the weighbridge.
To get the GTM leave van attached to tow vehicle at the weighbridge, but tow vehicle must be off the weighbridge and van on the weighbridge.
Hope this helps.

When referring to vehicle weights we have to be mindful of actual weights and weight limits. ATM and GTM are limits, you can't actually measure them just as you can't go out and measure a speed limit. They are declared weights limits that the vehicle manufacturer declares and records on the compliance plate. The following are copy and pasted from "Vehicle Standard (Australian Design Rule – Definitions and Vehicle Categories) 2005."

"AGGREGATE TRAILER MASS (ATM) - the total mass of the laden trailer when
carrying the maximum load recommended by the ‘Manufacturer’. This will
include any mass imposed onto the drawing vehicle when the ‘Combination
Vehicle’ is resting on a horizontal supporting plane."

Or simply the ATM is the maximum weight your can be when travelling.

"GROSS TRAILER MASS (GTM) - the mass transmitted to the ground by the 'Axle‘ or
'Axles‘ of the trailer when coupled to a drawing vehicle and carrying its maximum
load approximately uniformly distributed over the load bearing area, and at which
compliance with the appropriate Australian Design Rules has been or can be
established."

Or simply the maximum weight your wheels can impose on the road when the van is coupled.

The tare weight is something that is weighed, hopefully as the trailer is delivered from the factory. (often only the first one of a particular model is weighed and assumed to be the tare for future models even though extras are added to the van.)

"TARE MASS - mass of a vehicle other than a L-group vehicle ready for service,
unoccupied and unladen, with all fluid reservoirs filled to nominal capacity except
for fuel, which shall be 10 litres only, and with all standard equipment and any
options fitted."

Note, if you order accessories and the agent fits them then they are probably not included in the tare weight.

What generally happens is that the manufacturer weighs the van, both total weight and the weight on the axles. He then declares the ATM to be the total (tare) weight plus 400 kg (or 300 for single axles.) He also declares the GTM to be the weight on the wheels plus 400 (or 300.)

At that time the ball weight will be ATM - GTM. This is the only time that that relationship will be true. Any loading you put on or in the van will effect the ball weight, the effect will depend on where you place the load.

Switched on manufacturers will allow you ask for heavier loadings at the time of ordering and declare ATM and GTM figures to allow you to carry more than what some claim to be the standard load allowance for caravans. Also I stated above the unladen weight of your model of van will have grown since the first one is weighed. If the manufacturer has applied the original tare weight for the model to your unit then the load allowance will be less than you reckon on.

Quote " With the van fully loaded (water/gas) etc. the weight is 2540kgs which is ok with GTM but is 95kgs over ATM because ATM is Tare+payload+ball weight."

I don't get your figuring. The ATM is the figure you see on your compliance plate which you said is ATM is 2665 kgs. The 2540 figure, is that the total loaded weight or the group axle weight (weight on the main wheels?) If it is the total weight then you are 125 kg under the limit.

The figures you get on a weighbridge are "Actual loaded weights" and should not exceed The ATM and GTM that is on the compliance plate.

Ball weight is governed by the tug manufacturer or the limits of the towbar.
Whichever is the lesser.

EG Old ser 80 Cruisers had a 3500/350kg vehicle limit but before 1995 approx only had 2500kg towbars.

That then was all they could tow, so check your towbar stats as well.

Your figures in the OP dont add up and the actual ball weight may well be far different from what you have posted. It will also be an empty weight probably.

Normally it is ATM minus GTM gives you supposed ball weight which in your case should be 127kg.

My Coromal loaded was 2865 with a 300kg actual measured ball weight.

Load rig up as if you are going away Everything in it, food, clothes,tools genny, everything No good having half a load.
Take it to a scale Pull it on with tug off Get figures Gross weight Unhook with jockey wheel on scale get figures Actual loaded weight. Back it up so only jockey wheel on scale get figure. Ballweight

All done unless you also want combined weight then put whole rig on scale with you mum kids everything in both vehicles, full fuel tanks the whole nine yards.

Only way to know true weights. Then go home and chuck out what you dont need to get down to legal weights. Dont laugh we had to LOL

Bard & Jen,

I agree the quickest way is to just drive over the bridge so your vehicle is just off it and your van is on it. Just jack off the ball with the jockey wheel and when you get off the bridge yourself ask the operator for a weight, then just drop the van back on the ball.

Give the bridge operators a ring and ask if they have a quiet time to give yourself a little leeway.

I am a touch over my ATM so I had the ATM lifted by a licensed certifier. I just gave him the chassis max weight, axle group max weight and tyre max weights. He came to our house, checked the max weights, took a few photos for the audit inspectors and engraved a mod plate. Total cost $200 and from the time I first phoned it was 2 hours to all finished.

I only wanted 50kg extra but he said lets take it up to the chassis max weight which was up another 150kg.