The truth about 3 500kg towing

One of the big selling points of the latest crop of family-friendly, dual-cab utes is their impressive three-tonne-plus towing capabilities.

By Chris Fincham

Three-tonne-plus towing truck
Three-tonne-plus towing truck

When the new Toyota HiLux arrives (in Australia) next month, there will be no fewer than six one-tonne utes capable of towing up to 3 500kg, including the Holden Colorado, Isuzu D-MAX, Nissan Navara, Mazda BT-50, Ford Ranger and the ageless Toyota 79-series.

Not far behind are Mitsubishi Triton (3 100kg) and Volkswagen Amarok (3 000kg).

That’s in stark contrast to three years ago, when only three dual-cab utes offered a maximum 3 500kg braked towing capacity.

But does that mean you should rush out to buy the latest Ranger or D-MAX to tow the family’s 23ft caravan on a “Big Lap” of Australia?

Maybe, but only after giving serious thought to another set of “numbers” just as important as the ‘official’ tow rating advertised by the ute manufacturer…

We can offer this advice from real-world experiences of towing three-tonne caravans with three different dual-cab utes — the D-MAX and the latest top-spec Triton and Navara — in recent months, with less than sterling results.

What they don’t mention in the TV ads is the vehicle’s GCM (Gross Combination Mass) and GVM (Gross Vehicle Mass), which are all-important. GCM is the maximum weight of the tow vehicle and trailer combined while GVM is the maximum weight of the fully-loaded tow vehicle.

In the case of the top-spec Navara ST-X, for example, which has a kerb weight of 1 921kg, GVM of 2 910kg and GCM of 5910kg, towing all of 3 500kg leaves just 489kg for occupants, luggage and any optional or after-market accessories fitted like a bullbar or canopy.

It’s a similar story with the other dual-cab utes, most of which have remarkably similar specs — a GCM around six tonnes, GVM around three tonnes and kerb weight around two tonnes, give or take 100kg or so.

So unless you’re prepared to go on holidays with just the dog and some fishing gear, it’s quite easy to eclipse the GCM, putting your safety not to mention your insurance coverage and criminal record at risk in the event of an accident or roadside police check.

And don’t forget the axle load rating, and the weight on the tow ball which can cut intoGVM. For example, a typical 300-350kg ball weight of a 3500kg caravan effectively reduces the Navara’s payload by almost half (410kg).

Whether it’s for marketing reasons or otherwise, Mitsubishi’s and Volkswagen’s more conservative tow ratings at least allow for a more realistic 600kg or so payload when towing at the max.

But all this doesn’t alter the fact there’s still six tonnes to play with, regardless of ute and however you decide to slice the pie.

Then there’s engine output; another important factor in real-world towing. Simply, you want as much torque as realistically possible, delivered from as low down in the rev range as possible. While most dual-cab utes now offer a healthy 400-500Nm from (in most cases) relatively small four-cylinder turbo-diesel engines, most have to work pretty hard to motivate a five-tonne-plus rig over hill and dale.

It’s all fine cruising along on the freeway, but try and overtake safely or accelerate up a hill — as you might need to in an emergency — and there’s often little in reserve.

It’s for this reason experts recommend towing no greater than 85%, or no more than three tonnes for a 3 500kg rated ute. And often that’s still pushing it.

Putting less strain on the engine also delivers significant fuel economy benefits, with both the Navara and Triton tow tugs regularly topping 20L/100km when tackling terrain more challenging than flat highway.
By comparison, the 183kW/600Nm, 2500kg Land Rover Discovery 4 we drove recently surged effortlessly up hills like there was a tiny box trailer attached, rather than a big van behind — and for a more wallet-friendly 16,5L/100km to boot.
While there are a host of factors that influence towing stability, including speed, cross winds, road surface, tyre pressures and tow vehicle and trailer centre of gravity, one especially relevant to one-tonne utes is the distance between the rear axle and towball. Most utes have more than one metre of rear overhang, which is not ideal.
Throw in the average two-tonne kerb weight — or just 60% of a 3 500kg trailer —– and there’s an argument they’re also too light to provide a stable platform when towing.
This can contribute to the unsettling “tail wagging the dog” effect, where even minor trailer sway can upset the front-end balance of the ute and adversely influence steering.
Of course, some of these issues can be addressed with after-market modifications such as weight distribution hitches and sway controllers, by reducing speed and loading the vehicle and trailer correctly.

We know one importer of super-sized American caravans that often uses Japanese utes for towing, but only after they’ve had expensive suspension upgrades to ‘stiffen’ the rear-end and help settle the ride.

There’s also the outspoken owner of a well-known Queensland off-road caravan manufacturer who has firm views on the subject: a Toyota 200 Series LandCruiser is his pick for heavyweight tow jobs, with a converted American pick-up like the Ford F-Series the best all-round option (if comfort and passenger carrying ability remain important).

His favourite is the Dodge RAM, after trying many different models over the years. As well as the obvious advantages (3000kg-plus kerb weight, 4 500kg-plus towing and 11 00Nm-plus torque from the Cummins engine), he argues the Ram’s extended platform provides more control in an emergency swerving situation that might put a smaller, less stable ute on its roof.

The good news is that the Ram will soon be available in Australiawith a factory-backed warranty through Fiat Chrysler Australia. Though pricing is likely to be prohibitive, in my book the peace of mind from using a tow vehicle ‘over-engineered’ for the job is money well spent in the long run.

I look forward to tow testing one of the big American trucks later this year to see if that’s true…
With this in mind, perhaps another “golden” rule for heavyweight towing should be that the price of the trailer should never exceed the tow vehicle.

With the increasing number of big, expensive caravans and trailer boats on the road today, that could immediately rule out many ‘borderline’ tow tugs and make it easier for buyers to navigate the “numbers game” minefield outlined above. — motoring.