VAN RULES, OK?
For a week away or the big lap, your towing capacity is as critical as your budget
The holiday hordes are back at work, so if you’re one of the lucky people not joining them, now is an ideal time to hit the road — for a cruise along the coast or something more ambitious such as a lap of the wide brown land. All you have to do is hitch up the caravan and take off, right?
Not quite. Some things in life on face value should be pretty straightforward — delve deeper and they’re anything but. Welcome to the dark and mysterious world of towing.
How difficult can it be? How many rules can you have for the simple act of dragging a trailer around? Surely you just buy a trailer or caravan that’s within your vehicle’s towing capacity?
The answers, in order, are: it’s more difficult than you think; lots; and no.
Mistakes can be painful, expensive and illegal. Here’s what you need to know.
IT’S ALL ABOUT THE MATHS
Your most important tool when deciding what tow vehicle, van or trailer to buy is a calculator, and your most important references are manufacturers’ specifications.
You need to do the numbers to make sure you comply with all weight limits, because if you have a crash and need to make an insurance claim, the first thing the insurance company will do is check. If you’re overweight, you’re illegal, so your claim can be rejected.
You can also be charged with a range of serious traffic offences, depending on which state you’re in.
Towing is governed by a complex web of maximum weight limits, primarily gross vehicle mass (GVM), gross trailer mass (GTM) and gross combined mass (GCM). See Towing Decoded box.
DON’T TAKE A MAKER’S CLAIM AS GOSPEL
Manufacturers’ maximum towing weight claims are usually meaningless and you believe them at your peril. It’s ridiculous that makers can claim figures far in excess of the legal maximum that their fully laden vehicles can actually tow — but it’s common practice.
The legal maximum weight for your vehicle and trailer, hitched together, must be less than the combined, individual legal maximum weights for the vehicle and trailer.
Technically speaking then, gross combined mass must be less than the sum of gross vehicle mass and gross trailer mass.
Surely it’s a case of one plus one equals two?
Not on Planet Towing, it’s not.
We’ll do a calculation using the top-selling Toyota HiLux SR5 automatic to illustrate the intricacies. For the figures on other popular utes and SUVs, see the How Much Can They Really Tow? box.
The HiLux’s legal maximum gross combination mass is 5650kg. Its gross vehicle mass of 3000kg, plus its maximum claimed towing capacity of 3200kg, equals 6200kg — which is 550kg more than its legal maximum gross combined mass.
We’re assuming here (and in the other vehicles listed) that the HiLux is fully loaded to its GVM, which includes 955kg of payload.
If you’re buying a tow vehicle, look at its maximum gross combination mass. Deduct its gross vehicle mass. If you want to play it safe with a reasonable buffer for payloads, treat this weight as what you can safely and legally tow.
It will almost always be less than the manufacturer claims.
In the HiLux’s case, you subtract its 3000kg GVM from its 5650kg GCM, which leaves you with 2650kg to tow.
If you’re buying a trailer, deduct its aggregate trailer mass (ATM) from your tow vehicle’s gross combined mass.
If the result is significantly less than your gross vehicle mass, you need to choose a lighter trailer, or a new tow vehicle.
Again using HiLux, if you’re looking at a trailer with an ATM of 3200kg, subtract that
from the GCM (5650kg) and you’re left with 2450kg — or 550kg less than HiLux’s actual GVM. You can check your weights at a public weighbridge.
THEN THERE’S TOWBALL DOWNLOAD
Is 10 per cent towball download the legal maximum? No. Up to 15 per cent is acceptable.
In NSW, Roads and Maritime advises a download of 5-10 per cent. In Europe, the legal maximum is a mere 75kg, no matter what the weight of the trailer.
If you exceed 10 per cent, you might need a weight distribution hitch to keep the outfit level — but then you get into the thorny issue of warranty coverage.
Most vehicle manufacturers quote a maximum permissible towball download in their specifications. In many cases it’s a lot less than 10 per cent of their claimed maximum towing weight, so check.
If you exceed the manufacturer’s stated maximum towball download, with or without a weight distribution hitch, you’re giving them grounds to reject any warranty claim.
You can also alter the towball download by changing the payload distribution in your trailer or van but this needs to be done with care.
Moving payload to the rear to lessen towball download can cause the trailer to become unstable and create traction issues on your tow vehicle. Trailer payload should be carried as low as possible, and centred over the axle(s).