Trying to learn the ins and outs of towing weights? It’s time to strap in for a crash course!

COMPILED BY MICHAEL BORG

Let’s face it, we all love to bring the whole kit-and-kaboodle along on our adventures. It’s how we ensure we’re comfortable out in the bush and have plenty of things to keep us entertained and thoroughly enjoying ourselves. The big question is, have you ever spared a thought for the effects of that extra weight? Heck, is your camper capable of carrying the kid’s bikes, the boat and fishing gear, and half the contents of your home? Well, before you start loading up all of your adventure gear, there is more to consider than meets the eye.     

UNDERSTANDING THE LINGO

First things first, we must understand your camper trailers specifications relating to weight. However, it can be a little tricky to get your head around. So, lets dive straight in the deep end, shall we?

TARE MASS (TRAILER)

This is the mass of your trailer as specified by the manufacturer, with no payload.

ATM (AGGREGATE TRAILER MASS)

This is the tare mass of your camper, plus its maximum payload. Put simply, it’s the maximum your camper trailer is allowed to weigh in total.

GVM (GROSS VEHICLE MASS)

The maximum weight that your vehicle can weigh in total. This includes the actual weight of your car, passengers and luggage and even tow ball weight when hitched to a trailer. Put simply, the GVM is your vehicles Tare Mass plus its Maximum Payload. 

PAYLOAD

Payload is any mass you add to the vehicle or trailers tare mass. This includes, but is not limited to luggage, aftermarket accessories and even passengers. 

MAXIMUM PAYLOAD 

The maximum weight that can be loaded into the trailer for towing. This includes things like water, gas and any accessories added.

TBM (TOW BALL MASS)

This is the mass exerted on the tow ball by your fully packed caravan. When your caravan is hitched, this mass is included in your tow vehicle’s payload.

GTM (GROSS TRAILER MASS)

This is the maximum weight of the loaded caravan that can be supported by its wheels, not counting the portion supported by the car when hitched – or jockey wheel when parked. 

GCM (GROSS COMBINED MASS)

The gross combined mass is a combination of the maximum allowed mass of the trailer and the maximum allowed mass of the vehicle. 

TOW BAR AND COUPLING SPECIFICATIONS

Once you are satisfied your vehicle can safely and legally tow your camper trailer and any gear you throw on top, you’ll need to check a few other bits and bobs that are often forgotten about, too. Yep, you guessed it, the load limits of your towing apparatus should be verified as well. This includes your vehicles tow bar and the trailers coupling. If any of these components are rated too low, an upgrade will be required.  

What catches most of us out is the maximum allowable tow ball weight, which can largely vary depending on the tow bar fitted to your vehicle.

LOAD POSITIONING

As every camper trailer design differs, so too does the way it reacts to extra weight being placed at different locations around its structure. Ultimately, to ensure towing stability the deciding factor is balance. Think of your trailer like a seesaw, with the axle and wheels being the centre pivot point. Adding too much weight to the rear of your camper is basically leveraged to reduce the weight on the tow ball.  This can result in the trailer becoming unstable, especially at higher speeds. Excessive weight at the front places added weight to your vehicles tow ball, which can result in decreased braking capability, reduced steering quality, and poor overall stability. In most cases, it’s best to position any extra weight directly over the axles of your trailer, which is where the weight receives the least amount of leverage and is at its most centred.    

CENTRE OF GRAVITY

The centre of gravity is equally as important as the positioning of the weight. In general, the higher the centre of gravity, the less stability is achieved. This is true for both on and off-road situations. For example, loading all of heavier items such as the tent poles, gas bottles and the tinnie up on top will increase the centre of gravity, so the negative side effects should be considered.  

LOADING TIPS

1. Place bulkier items either directly over the axle or in front of it. Your trailer is much more likely tio track straighter and maintain its stability.

 2. As the front of your trailer is anchored to your tow ball, the rear of your camper is subjected to harsher movements, especially on rough terrain. So, if you’ve got fragile items on board, they’re safer up the front!

3. Rear mounting points on trailers are often not designed for supporting heavy loads or for recovery use. Ensure you research their weight limits before relying on them.