The truth about 3500kg towing ratings: Comment

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

When the new

Toyota HiLux arrives here in October,
there will be no fewer than six one tonne utes capable of towing up to
3500kg, including Holden Colorado, Isuzu D-MAX, Nissan Navara, Mazda
BT-50, Ford Ranger, and the

ageless Toyota 79 series.

While not far behind are Mitsubishi Triton (3100kg) and Volkswagen Amarok (3000kg).

That’s in stark contrast to three years ago, when only three dual-cab utes offered the maximum 3500kg braked towing capacity.

But
does that mean you should rush out to buy the latest Ranger or D-MAX to
tow that maxi trailerboat to Bermi?

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…

REAL WORLD ADVICE
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 most
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 1921kg, GVM of 2910kg and GCM of 5910kg,
towing all of 3500kg leaves just 489kg for occupants, luggage and any
optional or after-market accessories fitted like a bulbar or canopy.

It’s
a similar story with the other dual-cab utes, most of which have
remarkably similar ‘specs’ – 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.

AXLE LOAD RATINGS
And don’t
forget the axle load rating, and the weight on the tow ball which can
affect GVM. 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.

TALKING TORQUE
Then there’s engine output;
another important factor in real world towing. Put 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 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 many experts recommend towing no greater than 85 per
cent of the maximum, or no more than three tonnes in the case of a
3500kg rated ute. And often that’s still pushing it.

TOWING ECONOMY
Putting less
strain on the engine also delivers significant fuel economy benefits,
with both the Navara and Triton tow tugs regularly nudging 20L/100km or
more 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
than big van behind, with 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 dual cab utes is
the distance between the rear axle and towball. Most utes have more than
one metre of rear overhang which is not ideal.

LIGHT TUGS HAVE SWAY
Throw in the
average two tonne kerb weight – or just 60 per cent of a 3500kg trailer –
and there’s a strong 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.

SPREAD THE WEIGHT
Our sister site http://www.caravancampingsales.com.au knows one importer of super-sized American caravans
that often uses Japanese utes as tow vehicles, 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 heavy-weight lugger is
the Dodge Ram, after trying many different models over the years. As
well as the obvious advantages (3000kg-plus kerb weight, 4500kg-plus
towing and 1100Nm-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 Australia with 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.

We 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 the 'golden' rule for heavyweight towing should
be that the price of the trailerboat should never exceed that of the tow vehicle.

With
the increasing number of big trailerboats and caravans on
the road today, that could immediately rule out many ‘borderline’ tow
vehicle options and make it easier for buyers to navigate the ‘numbers
game’ minefield outlined above!