Here's how to boost your towing capacity to 4500kg

Boaters who discover their rigs are overweight or above the industry-standard 3500kg aggregate trailer mass (ATM) can now opt for a six-wheel conversion of their dual-cab ute to increase its towing capacity up to 4500kg.

The ATM is the combined weight of the trailer, boat and its full load when it is not coupled to a tow vehicle. More and more maxi trailerable rigs, be they boats or vans, are tipping over the edge these days.

But RV Specialists from Cardiff, NSW, appears to have a solution that's gaining traction. The company has been offering six-wheel conversions of dual-cab utes for buyers of their large, Australian-built fifth-wheel caravans. Now they are getting orders from owners of other kinds of heavyweight rigs who require a more capable tow vehicle.

"We’ve had a lot of interest (in the six-wheel conversion) from caravanners, as all the manufacturers are pushing the weight limit, the off-road guys in particular," RV Specialists' boss Jim Kaufmann told our sister site caravancampingsales.com.au.

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.

MAZDA BT-50 CONVERSION
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 in Toowoomba, Queensland, which fits a unique 60:40 load share suspension where 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, you are also said to gain improved stability and handling and extra braking capacity from the braked rear axle in these six-wheel conversions for towing.

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

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

HOW MUCH DOES THIS COST?
Depending on type of tray and other accessories fitted, pricing for a six-wheel Mazda BT-50 is around $90,000 drive-away, which Kaufmann says is still good value compared to alternatives such as a four-tonne towing upgrade for the 200 Series LandCruiser, or more expensive American pick-up.

Kerb weight of the six-wheel Mazda 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.

The gross combination mass (GCM) is boosted to 8000kg, doubling payload to around 2000kg in the process.

Kaufmann says the 3.2-litre, five-cylinder engine in the Mazda 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.

Here's how the six-wheeler system works...

More at Six Wheeler Conversions, see www.sixwheeler.com.au.