What Is Trailer Sway and How Do You Prevent It?

What Is Trailer Sway and How Do You Prevent It?

Even the most experienced drivers have been through it — that terrifying moment when the trailer that you are towing starts to sway dangerously, causing a fishtailing effect that is not only frightening for you but also presents a real and present danger to other road users.

However, there are some simple steps that you can take, both in terms of how you load your trailer and how you drive, that can minimise trailer sway and give you a safer towing experience.

What causes a trailer to sway?

A swaying trailer can be extremely dangerous. Not only does it make your vehicle very difficult to control, but in the worst case scenario it can lead to the trailer tipping over completely, with potentially calamitous results.

Strong gusts of wind, when driving over a bridge or being overtaken by a truck or other large vehicle, for instance, can cause sudden, unexpected sway in your trailer and vehicle. You are also likely to experience heavy gusts of wind when driving in hilly or mountainous regions.

Rough, unsurfaced or uneven roads can also cause trailers to sway, while long downhill descents where speeds can pick up suddenly can also be challenging.

Excess speed is a (very preventable) cause of trailer sway, as is sudden and unexpected braking. Staying within speed limits (please note that some Australian states have lower limits when you are towing) will ensure that the risk of swaying is reduced, and will also make it easier to brake gradually when approaching traffic lights or other stopping points.

Having sufficient brake power in your vehicle for your trailer load and size will also ensure more stable towing, as will avoiding (whenever possible) sudden changes of direction or sharp turns.

Overloaded or poorly loaded trailers are a frequent cause of trailer fishtailing, as are towing vehicles that are not capable of pulling the weight, so ensuring that you load your trailer properly and within the appropriate limits will make your towing experience a safer one (regardless of whether you’re towing a flat top trailer, box trailer or tipper trailer).

How do you minimise trailer swaying?

Make sure your trailer is loaded correctly

Ensuring that you have loaded your trailer properly will go a long way to preventing it from swaying when you are on the road.

Make sure, for instance, that you know your trailer’s ATM (Aggregate Trailer Mass) as well as the towing mass of your vehicle (the maximum weight it is capable of towing), plus the rated capacity (maximum weight capability) of your tow bar.

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