Towing Tips Part 1
Understand the terms
Towing is a national pastime in Australia and plumbers are no exception when it comes to hitching up the work trailer, caravan, camper or boat.
Master Plumbers CEO Peter Daly explains the ins and outs of towing in a two-part series, starting with some helpful definitions.
Modern utes and full-size 4WDs have the power and torque to pull the heaviest loads comfortably compared with their earlier brethren, but this comparative ease of towing can hide some dangerous and costly traps.
This edition of Australian Plumbing magazine defines the terms. Think of this as a go-to list if you have any concerns about the weight you are about to tow or if you are in the market for a new workhorse.
Definitions
GVM – Gross Vehicle Mass is the total permissible weight of the vehicle fully loaded, including any weight on the tow ball.
GCM – Gross Combination Mass is the total permissible combined weight of the vehicle and what it’s towing, both fully loaded.
ATM – Aggregate Trailer Mass is the weight of the fully loaded trailer/ caravan and everything in it or on it, measured when uncoupled from the tow vehicle.
GTM – Gross Trailer Mass is the weight of the fully loaded trailer/caravan when connected to the tow vehicle.
Tow Ball Mass (load) – The vertical weight exerted on the vehicle’s tow ball by the fully loaded trailer/caravan.
When connected, this weight counts towards your vehicle’s GVM.
Tare Mass – For the towing vehicle is the weight of the empty vehicle with all its fluids (oils, coolant, etc.) plus a nominal amount of fuel (often 10 litres). For the trailer or caravan is the mass as specified by the manufacturer with no payload.
Payload – Any mass you add to the vehicle or trailer/caravan’s Tare Mass, including all passengers, luggage, accessories or additional gear (e.g. bull bar, drawers, toolboxes, gas bottles, etc.)
Towing capacity – The maximum allowable weight you can tow with your vehicle. This is 750kg for an unbraked trailer (i.e. one which relies on the brakes of the towing vehicle like a 6b4 trailer) and for trailers/caravans with their own brakes is set by the vehicle manufacturer (often in the range of 2000-3500kg but can be as high as 4500kg for very large utes).
Kerb weight – The weight of the fully-fueled vehicle, without accessories, passengers or luggage.
In part two of our towing series, Peter goes into detail about how weight is measured, providing helpful examples to ensure you are not creating a danger for yourselves or others. Keep this page handy as it will act as a quick, general reminder of what to look out for.
