What is a primary reason that braking forces may not be evenly distributed in a tractor/trailer combination?

Improper brake adjustments are a primary reason that braking forces may not be evenly distributed in a tractor/trailer combination. When the brakes on the trailer are not correctly adjusted, it can lead to differential braking between the tractor and trailer. If the brakes on one axle are either too tight or too loose, it will affect how much braking force is applied, causing the vehicle to pull to one side or lead to additional wear on certain tires. This can result in unstable handling, particularly during emergency stops or when descending steep grades, where precise braking balance is essential for safety.

While factors like varying tire pressure, driving on different road surfaces, and changes in weather conditions can also affect overall vehicle handling and braking performance, they do not directly relate to the mechanisms of brake adjustment itself. Hence, improper brake adjustments specifically target the brake system's functionality and its direct impact on braking force distribution.