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Ten causes of trailer sway

Pulling trailer has its own set of challenges to be considered, and keeping it stable is one of the most demanding. One of the most common problems encountered is trailer sway, and below are the 10 major causes.

Poor weight distribution

Be conscious of the trailer’s weight and adjust it if necessary. The weight over the hitch ball should be anywhere from 9 to 15 percent of the total weight of a fully loaded trailer. Anything less than that would require adding weight for ballast or positioning some existing weight at the front of the trailer.

Bad hitch adjustments

The best way to solve a problem is to prevent it from happening in the first place, and adjusting the hitch to suit the circumstance is a must. There are several hitch adjustments that work collectively to spread the tongue weight of the trailer, which are as follows:

  • Hitch ball height to keep the trailer level
  • Weight distributing bars to keep the tow vehicle level
  • Hitch head angle to keep the bars level

Tires lacking sufficient air

Be careful about driving with underinflated tires and keep to a schedule of routine tire maintenance that includes checking the pressure. Usually, the amount of air pressure needed can be found on the inside of the driver’s door. While you are at it, take a moment to check the tire tread and be prepared to have to change them out if they are too worn.

Wind coming from passing trucks/RVs

When something large like a truck passes you, the air pressure can push and pull against the trailer. Be prepared by observing the road ahead and checking your mirrors regularly, and gently steer in the direction of the sway to compensate.

Driving downhill

Take it slowly and gently apply the brakes if a sway develops (heavy breaking may cause the trailer to jack-knife). Use trailer brakes if you have them and if you feel the sway getting away from you accelerate if there’s room to do so safely.

Incorrect hitch ball spacing

Adjust the space between the tow vehicle rear axle and the hitch ball. The shorter the distance between the two, the safer the ride is going to be.

Excessive wind sheer

Strong winds can be very dangerous when trailers are being towed. Lateral gusts are particularly treacherous and can knock against the side of the vehicle with extreme force. If you can, avoid driving on a windy day (more than 20-25 mph.). If a strong wind develops while you’re driving, slow down and, if necessary, stop the vehicle completely and park by the side of the road until it subsides.

Unsuitable towing vehicle

It is unsafe for a small light vehicle to pull a large heavy trailer so make sure the vehicle you are using is appropriate for the job at hand. It should be able to pull the gross vehicle weight rating (GVWR) of the trailer without extraordinary difficulty.

No sway control system

Having a sway control kit installed can help stop sway from even starting. They typically rely on frictional forces to keep your trailer from shifting, and can prevent sway from increasing should it start. There are two types of friction sway control systems — independent and dependent.

Overloading your trailer

Carrying too much weight can cause the trailer to behave unpredictably. Keep it within the gross vehicle weight rating (GVWR) and gross combined weight rating (GCWR) and be sure to secure all cargo and distribute all the weight correctly.

For more information on towing safety, visit

About Jon Mills

Jon Mills is an avid RV enthusiast, and the creator of the "Route-1" low clearance avoidance system, the largest low clearance database ever devised for the USA and Canada. Available at He is also the producer of the popular "RV Pro Safety Guide," providing professional safety expertise for RV drivers. Currently available FREE for a limited time at So get your copy now.

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