Why are towing weights so perplexing?

There is still confusion and disagreement among even experienced caravanners, dealers and professional industry bodies over what constitutes safe and responsible loading of tow cars and caravans for those about to embark on a big road trip.

Victorian caravancampingsales reader Mark Coombes recently took the time to analyse his own caravan loading and towing habits for the rig, that he and his wife use for regular interstate trips: a 2017 Toyota Landcruiser 200 Series VX diesel towing a 15ft Legend Trackline off-grid caravan.

As Mark found out when compiling his spreadsheet, which he sent to us as only a guide, many factors affect a caravan’s towing stability. These include adjusting tyre pressures to the road surface and achieving the recommended ball loading, and adjusting the load distribution inside and underneath the caravan to ensure this, whether or not a weight distribution hitch is fitted.

Other factors include travelling speed and, of course making adjustments to reflect the surface you're driving on, be it sealed or unsealed.

Of course, you can engage a mobile weighing service to check out your caravan rig for the correct and legal loading before you leave, but Mark hopes to by-pass this by getting travellers to follow some basic guidelines and use common sense.

A starting point is to appreciate the relevance of weights, which means understanding acronyms or terms like Tare, ATM, GVM, Tow Ball Mass and payload.

While you can become fanatical about the correct distribution of weight, common sense and a basic understanding of what imbalance does to your rig’s braking or swaying, is more important.

Mark, like many of us, shakes his head in disbelief when he sees the things that many people mount on the rear bumper of their caravan, such as outboard motors, a nest of family bicycles, heavy tool boxes and the like.

While Colin Young, of the Caravan Council of Australia, agrees with much of Mark’s work, he laments the general lack of reliable information given to the towing public.

"The ignorance at a number of levels in the industry is incredible,” he said.

“This is matched only by the lack of ethics and the incompetence regarding full compliance with both VSB1 (Vehicle Standards Bulletin - Road Vehicles Standards Act) and the provisions of the ACL (Australian Consumer Law).”

Young says there is still significant misunderstandings of the important technical terms relating to caravans, especially when these terms form the basis of the majority of complaints - and subsequent litigation - that is badly hurting the caravan industry. 

One example, he says, is that many people continue to use the incorrect equation "that a GTM (Gross Trailer Mass) rating is actually the ATM (Aggregate Trailer Mass) or empty ball-loading rating".

“This is completely wrong, as there is no logical relationship involved," he said.

"The ATM and GTM are fixed ratings allocated by the manufacturer, in relation to the maximum-permissible ‘all-up’ and ‘axle(s)’ limits. The empty ball-loading is an actual mass that must be measured, and is obviously applicable only to the empty (Tare mass) condition.”

Young says education of drivers towing caravans is urgently needed. 

“Even though it is denied by many in the caravan industry, there are far too many accidents involving caravans on our roads," he said.

“For every serious roll-over accident that makes the evening TV news, there are many times that number of frightening incidents of caravans swaying badly and jack-knifing.  

“These issues are greatly exacerbated when the tow vehicle is not suitable for the particular caravan, especially when the various ratings of the tow vehicle are not high enough to safely and legally tow the caravan."

 “In many cases, while the GVM (Gross Vehicle Mass) rating and the tow rating may not be exceeded, the over-riding GCM (Gross Combination Mass) rating is illegally exceeded."  

To help ease the confusion, Young has posted a number of technical articles on the Caravan Council of Australia website that explain many of these terms in great detail, as well as other excellent advice on how to set up your tow car and caravan, or camper trailer, for a safe holiday.

Young said he is also working on a 'towing guide' spreadsheet which he hopes to make available soon.