Many caravanners are concerned about safety, and one of the more difficult aspects of vehicle safety for caravanners is staying on top of the specific requirements for ratings and masses. These are really important to get right, so if you’re not well versed in these matters, there’s no time like the present to start building your knowledge.
Be legal and be safe
Ratings and masses exist primarily to keep people safe: you, your passengers and other road users. It’s vitally important that both your caravan and your towing vehicle are legally compliant with Australian Design Rules and Australian Standards.
If you don’t have much experience when it comes to the technical side of things, seek help from a professional. They will be able to make the necessary adjustments and replacements to ensure that your vehicle and caravan are fully compliant.
If you have an older vehicle, keep a close eye on it, and be sure to get it checked regularly. The Motor Vehicle Standards Act came into play in 1989, so if you are rocking a vintage van that was manufactured before this time, be sure to get it checked for roadworthiness.
Manufacturers ratings and masses
Manufacturers ratings are there for a reason, and if you exceed the ratings for the maximum weight of your caravan, you lay yourself open not only to serious accidents on the road, but also to legal prosecutions.
Your caravan’s aggregate trailer mass (ATM) rating and its gross trailer mass (GTM) rating are determined by the manufacturer and cannot be exceeded, while the tare mass refers to the actual measured mass of the vehicle as supplied by the manufacturer.
The ATM rating equals the tare mass of the caravan plus the maximum weight it can carry, as specified by the manufacturer. This is the maximum your van is allowed to weigh on the road; exceeding this limit puts you in danger, legally as well as safety-wise.
When determining the ATM rating, the manufacturer considers issues like the number of people the van is able to sleep and the size of sleeping berths, the capacity of water tanks and gas cylinders, and the type of appliances and accessories. These are basically commercial decisions. In contrast, the GTM rating is based on engineering decisions, and takes into account the distribution of weight across the vehicle via storage compartments like water tanks, gas cylinders and luggage compartments.