Caravan sway is one of the most unsettling moments you can experience on the road. It often feels sudden, unpredictable, and out of nowhere — but in reality, sway almost always begins long before the caravan ever moves sideways.

Wind, passing trucks, road dips, and downhill sections often get the blame, but they’re usually just the trigger. The real cause of sway comes from deeper issues in how the caravan is loaded, set up and managed. Below we break down the major stability factors that matter most, then cover the secondary causes that can provoke sway when your rig is already close to the edge.

The Major Causes of Caravan Sway

These are the internal setup factors that determine how stable — or unstable — your caravan will be. If any of these are out of balance, the caravan becomes sensitive, and once sensitivity increases, it doesn’t take much for sway to start.

1. Speed — The Most Powerful Factor

Speed alone can take a stable setup and push it into instability. As your speed increases:

• the damping ratio drops
• the caravan becomes more responsive to side forces
• every setup has a critical speed where it stops self-correcting sway

This is why a rig that feels calm at 90 km/h may become nervous at 105 km/h. You haven’t changed anything about the load — you’ve simply crossed closer to the zero damping speed, where sway is no longer automatically controlled by the physics of the system.

2. Towball Weight Percentage & Load Placement

If speed is the "how fast," towball weight is the "how stable." Towball weight percentage is one of the strongest predictors of sway resistance.

When TBW is too light:

• the centre of mass shifts rearward
• stability drops sharply
• the zero-damping speed drops
• sway can be initiated by minor disturbances

When TBW is too heavy:

• the tow vehicle’s rear axle is overloaded
• steering becomes light
• the rig can feel vague or unpredictable

Correct load placement is also essential. Heavy items placed behind the axle group — even a single 20–30 kg item — can drastically reduce TBW and increase sway sensitivity.

3. The Caravan Being Level (Front-to-Rear Attitude)

This is one of the most misunderstood elements of caravan stability, especially because the effect changes depending on the suspension design.

Single Axle & Load-Sharing Dual Axles

These setups behave similarly because the load is naturally shared or pivoted around a single effective point:

• Nose-down increases towball weight
• Nose-up decreases towball weight

A level caravan transmits braking forces more horizontally and cleanly through the chassis of both vehicles. When the caravan is nose-up or nose-down, some of that force is wasted pitching the combination instead of helping it remain stable under braking.

Dual-Axle Independent Suspension

This category behaves very differently — and is far more sensitive. Because each axle acts independently, the caravan does not self-level. Nose-down tends to:

• heavily load the front axle
• unload the rear axle
• reduce effective towball weight
• shift the pivot point forward
• shorten the effective wheelbase

Nose-up can:

• load the rear axle
• raise the centre of mass
• change braking behaviour

Dual-independent-suspension caravans should always be towed level. Even small changes in attitude can have a significant impact on stability.

Even axle loading:

A level caravan shares weight evenly across both axles, giving all tyres maximum contact and grip to resist sideways twist. An unlevel van unloads one axle dramatically—often the first to slide and start sway.

4. Tyre Pressures & Tyre Behaviour

Tyres determine how well the caravan maintains lateral grip.

Underinflated tyres:

• flex more
• respond slower
• increase sway sensitivity

Overinflated tyres:

• reduce contact patch
• feel twitchy

Side-to-side pressure mismatches can create a constant yaw bias. Correct tyre pressures — for both the caravan and the tow vehicle — are simple yet powerful stability improvements.

5. Wheel Alignment & Axle Geometry

A caravan with poor alignment will not track straight, even with perfect towball weight. Alignment issues include:

• toe-out
• uneven toe between axles
• bent stubs
• uneven camber
• tyre scrub that indicates constant lateral force

If the caravan constantly “wants” to go a certain direction, the tow vehicle must constantly correct it — reducing sway resistance.

Adjustable Hitches and How They Affect Stability

While adjustable hitches are convenient for setting the correct towing height, they can also reduce stability in ways many people don’t realise. Most adjustable hitches position the towball further behind the vehicle’s rear axle compared to a one-piece hitch tongue. Even a modest increase in rear overhang gives the caravan a longer lever arm to act on the vehicle, meaning any small yaw movement at the caravan produces a larger steering influence at the towball.

This matters because the towball isn’t just a connection point—it effectively becomes a steering link between the caravan and the tow vehicle. By extending it further rearward, the caravan gains more ability to “steer” the car from behind, making the whole combination more sensitive to wind, passing trucks, or sudden road inputs.

A longer hitch position also changes weight transfer. Although the towball weight in kilograms stays the same, its effect increases, placing more load on the rear axle and reducing load on the front wheels. When the front axle becomes lighter, steering authority decreases and the rig becomes less stable at highway speeds. Adjustable hitches also introduce small amounts of flex through their multi-piece construction, which further reduces the natural damping of the setup.

For these reasons, adjustable hitches are a contributing factor to sway. They don’t cause sway on their own, but they reduce the vehicle’s margin for error and make the combination more reactive to disturbances.

6. Driver Input

Caravans respond to the driver as much as they respond to the road. Actions that amplify sway include:

• sudden steering
• overcorrection
• lifting off the throttle quickly
• braking mid-oscillation
• steering downhill where TBW is reduced

Smooth driving preserves stability and helps the rig absorb external forces without oscillating.

Secondary Causes of Caravan Sway

These factors rarely create sway on their own — but they easily trigger sway when the main stability factors are already marginal.

Environmental Triggers

• Crosswinds
• Passing trucks and low-pressure bow waves
• Oncoming heavy vehicles
• Downhill braking (reduces TBW)
• Road dips that momentarily unload an axle
• Off-camber road sections

Mechanical or Setup Contributors

• Uneven tyre wear
• Worn shocks (car or caravan)
• Soft tow-vehicle rear suspension
• Incorrect WDH setup
• Play or wear in the coupling
• Uneven electric brake performance
• Towbar flex
• High centre of gravity caravans
• Internal loads shifting during travel
• Caravan significantly heavier than the tow vehicle

Final Thoughts

Most caravan sway events begin long before the caravan visibly moves sideways. Stability is built — or lost — through the major factors: speed, towball weight, load placement, the caravan being level, tyre pressure, alignment, and driver behaviour.

If even one of these factors is marginal, the caravan becomes sensitive. When several are marginal, all it takes is a gust of wind or the bow wave from a truck to expose the weakness.

To understand how these factors combine at speed — and why caravans stop self-correcting sway — read our full article on Zero Damping:

Read: Zero Damping — What It Is & Why You Should Care