Securing loads on cars, caravans, and trailers

By: Brendan Batty

On longer getaways, the amount of gear and supplies needed to make your trip even more comfortable and enjoyable can really add up. Getting those essential (and non-essential) items correctly loaded is an important part of having a safe and happy trip.

Before you go, you’ll need to consider the impact of adding weight, bulk and even odd-shaped attachments to your vehicle.

Whether you’re loading a couple of bags and surfboards for a week in Esperance or a four-wheel drive, trailer and roof racks for a long road trip up north, you’ll need to make sure everything is packed safely, efficiently and legally.

There are pages and pages of recommendations, rules and guidelines about loading things into or onto a vehicle, but before you go, ask yourself these simple questions: Could it cause a crash? Will it move, come loose, or potentially cause an injury? Will it make the drive less comfortable? You should be able to answer ‘no’ to each one.

Don’t exceed your car’s load limit

Every light vehicle must abide by certain limits when it comes to loads. Light vehicles (be that a car, four-wheel drive, caravan or trailer) and their load cannot exceed the weight limits set out by the manufacturer or relevant authority (see our Loads Glossary below).

Vehicles loaded up for the holidays can easily overstep one or more of these limits.

With a box-trailer loaded up with camping gear, it doesn’t take much for it to weigh more than 750kg – the upper limit of a trailer not fitted with brakes. Regardless, the loaded mass must not exceed the towing capacity of any part in vehicle/trailer combination, and this includes the towbar and towball.

Equally, with a large caravan hitched up and a load of gear in the back of a four-wheel drive, it’s not hard to overload the rear axle or exceed the Gross Combination Mass (GCM), even if neither car nor caravan is individually overloaded.

In one Victorian police blitz focused on vehicles towing caravans, nearly 60 per cent were found to be overweight in some manner.

If you suspect your vehicle is on the heavy side, consider getting it weighed. There are public weighbridges all over the state or you can buy personal vehicle scales for a few hundred dollars. They’re reasonably accurate, so they’ll give you a ball-park indication.

It's against the law to drive a vehicle carrying a load that makes it unsafe or unstable.

Don’t load heavy objects high in your car

It’s important to carry your heaviest items low in the vehicle and, where possible, between the axles in a vehicle, or directly above the axles in a trailer. Don’t carry very heavy items on the roof or high up.

If you’re towing a caravan or long trailer, avoid placing heavy loads at the very rear, even if it helps balance the load, as this will cause trailer sway and instability.

Those towing a heavy trailer or caravan should consider using a weight-distribution hitch to improve braking and steering performance.

Always use correctly rated restraints for roof racks

You can’t drive a vehicle that’s carrying a load unless the load is restrained on the vehicle by an appropriate system.

If you’re securing things to roof racks, in a trailer, in your tinny or on the outside of a caravan, it must be securely attached by a device rated for the load.

For instance, a ratchet strap with a suitable load rating is acceptable. That old rope from Grandpa’s trailer, an occy strap or your boat’s canvas cover is not.

Even if you’re confident everything in your roof racks is well fastened, for peace of mind, it’s best to safely pull over at some point into your journey and check that nothing has become loose after being exposed to headwinds and bumps as you travel.

Specifically referring to boats, Main Roads WA told us, “If you carry items in a boat, make sure they are secured. Just because the item is in the boat doesn’t necessarily mean it is secured. There are many cases when items have been blown out of a boat by wind pressure and hit cars travelling behind or in the opposite direction.”

Ensure items protruding from your car are within legal limits

It’s illegal to drive a vehicle carrying a load that extends from it that could injure a person, obstruct the path of other road users, damage property or could fall from the vehicle or just become dislodged and create a dangerous hazard for other road users.

In Perth alone, Main Roads responds to approximately 50 callouts a week to remove things from the road that have fallen from vehicles, so it’s quite common.

A vehicle and its load can’t measure more than 2.5m wide, 4.3m high, and in WA, can’t have a load that extends more than 1.2m in front or 1.2m to the rear of the vehicle, or 150mm beyond the extreme outer portion on either side (like a roof-rack mounted awning or the longboard you’ve got hanging out the corner of your ute’s tray).

Overstep these, and your vehicle is exceeding the maximum legal dimensions and projections allowable on WA roads.

Again, for boats, Main Roads says, “If your boat is wider than 2.5m, then you also require a Main Roads Permit to move the boat on a public road.” And if your load obstructs a rear number plate, organise an auxiliary number plate through the Department of Transport.

Items inside your car must also be correctly placed

It’s not just people and pets we need to secure in a car. The Road Traffic (Vehicle) Regulations 2014 says, “A load on a vehicle must not be placed in a way that makes the vehicle unstable or unsafe.”

Similarly, the National Transport Commission’s Load Restraint Guide says, “You must restrain any load you are carrying on a light vehicle so that [it stays] on the vehicle during normal driving conditions – this includes heavy braking, cornering, acceleration and even minor collisions”.

While both refer to a load ‘on a vehicle’, the Department of Transport confirmed that we need to take the same precautions ‘in’ a vehicle, as items ‘on’ a seat or ‘on’ the floor are still considered on the vehicle.

In a sedan, the problem is solved simply by putting items in the boot. In a ute or van, put them in the tray or cargo area (don’t just rely on the tray or the barrier/window behind the cabin to keep your items from moving around, make sure they are secured). If the back seat’s the only place, put heavy things on the floor, rather than on the seats.

In an SUV or wagon, if possible, get a cargo barrier fitted. Alternatively, use the tie-down points that are an under-used feature of nearly every wagon to secure the load (hot tip – hook the straps to the forward points before loading the car, and dangle them over the back seats, so they don’t get lost as you pack everything in).

Don’t use occy straps - they’re not good enough. Store things low down, against the back seats and below the height of the head restraints, which not only keeps a barrier between you and them but means your vision out of each window isn’t obstructed.

In a motorhome or campervan, pack everything away before driving and check that all cupboards and drawers are closed correctly.

Whatever it is you have loaded onto or into your vehicle and trailer, check on it regularly during the trip, as things will shift, which could cause straps to loosen or make room for things to move.

Unsafe loads impact ride comfort and vehicle handling

Vehicle comfort has been shown to affect driver fatigue, and a poorly loaded vehicle will make things uncomfortable.

A harsh ride because the suspension is overloaded might be the most obvious example but even the constant hum of a loose tarp vibrating in the wind, the repeated complaints of children cramped in the back seats with luggage at their feet, or worry caused by a slightly swaying caravan are very tiring.

Consider packing less, or if that’s not possible, invest in the roof racks, trailer, or even the vehicle you need to safely and responsibly carry everything you need.

After all, you’re meant to be on holidays, relaxing and enjoying yourself.

Loads glossary

GVM - The Gross Vehicle Mass is the most a motor vehicle can weigh, including its load, fuel, accessories and passengers.

ATM - The upper limit of how much a trailer or caravan can weigh while being towed, specified by the manufacturer.

GCM - The Gross Combination Mass is the most a motor vehicle and its trailer can weigh, including its load, accessories and passengers. It may be less than the sum of the GVM and ATM.

Axle loads - The maximum allowable load over a specific axle, as stated by the manufacturer.

Un-braked towing limit - The maximum weight of a trailer that can be towed without auxiliary trailer brakes fitted. It’s never more than 750kg, but often less.

Braked towing limit - The maximum weight of a trailer or caravan a motor vehicle can tow if the trailer and motor vehicle are fitted with an auxiliary trailer brake system. Judged by the physical weight of the trailer, not it’s specified ATM. It’s rarely more than 3500kg, but often less.

Maximum tow ball download or mass - The weight limit which can be carried by the tow bar. It’s rarely more than 350kg, but often much less.

Roof load - The maximum safe weight you can carry on a vehicle’s roof, including the weight of the roof racks.

Last updated: December 2024