How to tow 4500kg with your dual-cab ute

Caravanners who discover their rigs are overweight or above the industry-standard 3500kg ATM are increasingly opting for six-wheel conversions of popular dual-cab utes that can increase towing capacity up to 4500kg.

Cardiff, NSW-based RV Specialists has been offering six-wheel conversions of dual-cab utes for buyers of their large, Australian-built fifth-wheel caravans, but are now getting orders from owners of heavyweight caravans who require a more capable tow vehicle.

“We’ve had a lot of interest (in the six-wheel conversion) from caravanners, as all the (caravan) manufacturers are pushing the weight limit, the off-road guys in particular,” RV Specialists’ boss Jim Kaufmann said.

He said one caravanner recently ordered a six-wheel conversion after discovering his rig weighed 6400kg fully loaded, or above the gross combination mass (GCM) of his Isuzu D-MAX tow vehicle.

>> Related reading: The truth about 3500kg towing

RV Specialists has so far concentrated on six-wheel conversions of the Mazda BT-50, including basic tradie aluminium tray as well as custom fibreglass tub versions. They come with either a fifth-wheel hitch or tow bar, both rated to 4500kg (fifth-wheel can be increased to 5500kg).

The 6x4 fit-outs are done by Six Wheeler Conversions, which fit a unique 60:40 load share suspension in which around 60 per cent of the load remains on the load axle in most situations, and 40 per cent on the ‘lazy’ third axle (see video below for a full explanation of how it works).

Apart from the one-tonne towing increase, the Toowoomba, Queensland-based business cites a number of benefits of the six-wheel conversion for towing, including improved stability and handling and extra braking capacity from the braked rear axle.

It also claims the factory ute’s 4WD ability is retained or even improved, thanks to up to 300mm of articulation between the rear axles.

With the rear tray extended by only 200mm, Kaufmann said the six-wheel BT-50 is still compact enough to make it more appealing than a larger light commercial truck.

Depending on the type of tray and other accessories fitted, pricing is around $90,000 drive-away, which he said is still good value compared to alternatives such as a four-tonne towing upgrade for the 200 Series LandCruiser, or the more expensive locally-converted US pick-ups.

Kerb weight of the six-wheel BT-50 is around 2600kg, with both fuel tanks full including an extra 140-litre tank fitted. The gross vehicle mass (GVM) is pegged at 4495kg to avoid the requirement of a light rigid truck driver's licence, while the GCM is boosted to 8000kg, doubling payload to around 2000kg in the process.

Kaufmann says the 3.2-litre five-cylinder engine in the 4WD BT-50 “has no dramas” coping with the extra weight, and the six-wheelers are stamped with a new ‘second stage manufacturer’ compliance plate.