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Tow More - up to 4500Kg with GCM Increase

Is your rig over loaded? The Truth about GVM’s and GCM’s and Six Wheelers.


Modern utes and four wheel drives boast some impressive figures from their respective manufacturers about their towing and load carrying capabilities, with many stating 1 tonne payloads and 3½ tonne towing. What they don't tell you is that you can have one or the other, but not both. So if you are towing a 3,500Kg trailer, and have a fully loaded tow vehicle fitted with bull bar, side steps, canopy, tools etc, then there is a good chance that you are exceeding the legal capacities of the vehicle. This not only reduces the safety of the whole rig, but can potentially void insurance cover if the worst was to happen.


So with those figures in mind, there has to be a compromise on either the weight of the trailer, or the load the vehicle can legally carry. And that is where our Six Wheeler's come into their own.


GVM  Let us explain the terminology - Gross Vehicle Mass is the maximum total weight of vehicle and load, including all people and accessories in the vehicle, including fuel. 

GCM Gross Combination Mass is the sum of the GVM and the weight of the maximum loaded trailer.

For the bulk of our completed Six Wheeler conversions, we are able to achieve a GVM increase up to 4,495Kg, and a towing capacity increase to 4,500Kg giving a theoretical GCM of 8,995Kg.

In the case of utility vehicles, both these OEM figures are set by the vehicle manufacturer and have more to do with the warranty than the law of the land.  The Federal law in Australia clearly states that, in the absence of a manufacturer’s recommendation, the vehicle is allowed to tow 1.5 times its tare (empty) weight.

The important thing to consider with a vehicle converted to become a Six Wheeler is that along with that conversion is a new Compliance Plate.  Six Wheeler Conversions Pty Ltd (SWC) is a registered 2nd Manufacturer.  So the first manufacturers recommended GCM goes out the window for brand new vehicles we convert. For previously registered vehicles the stated GCM's can vary depending on the individual states policies.

With the conversion completed, the vehicle now tares a fair bit heavier as well.  As a rough rule of thumb, the Six Wheeler normally tares between 2.6 and 3 tonne.  This allows a trailer weight of between 3,900Kg and 4,500kg.  As long as it is braked properly.

Add to this the new GVM that SWC puts on the new compliance plate, the GCM is usually between 8 and 9 tonne.  This is all a fair bit safer than the combination would have been with the vehicle on only 4 wheels and within the original GCM.  The new combination has an extra axle giving better weight distribution, and better road grip,  and far better braking ability.  So overall a far better, and safer combination.

Then it gets even better if the trailer is a gooseneck type.  Once the trailer hitch is forward of the rear axle, then the ball weight becomes part of the load.  And it stops being a dead weight at the end of a towbar.  So the steering and load distribution on the vehicle becomes far better.  Gone are the tendencies of the trailer to sway and overtake control of the towing vehicle.   And the extra brakes help too.

But legally it helps as well.  Because a tonne or so can be on the vehicle as load,( and the trailer is then considered to be 3.5 tonne), then the lighter Six Wheeler can still legally tow a 4.5 tonne gooseneck.  This is the biggest trailer allowed with electric brakes.  Above 4,500Kg trailer weight and you have to have a truck in order to get legal brakes.

And so, from a legal aspect, a Six Wheeler is the only sensible way to tow a gooseneck trailer.  And it is also the only safe way to control these trailers with heavy loads. Because of the way we build our new Dingo EYE- -TIE tray bodies, and the way we mount them to the chassis,  a gooseneck or 5th wheeler hitch can easily be added into the new tray as we build it for maximum strength and durability.