What is the most common cause of trailer sway?

The most common cause of trailer sway is imbalance in load distribution. When the load in a trailer is not evenly distributed, it can create a situation where one side of the trailer is heavier than the other. This imbalance leads to instability, making the trailer more susceptible to swaying, especially at higher speeds or during sudden steering maneuvers. Properly loading the trailer by balancing the weight and ensuring that it is secured can significantly reduce the risk of sway.

While factors such as incorrect speed limits, using the wrong type of trailer, and driving on rough terrain can influence stability, they are not as directly related to the fundamental issue of how the load is distributed within the trailer. The emphasis on load distribution highlights the importance of proper loading techniques in enhancing trailer stability and safety on the road.