What issue may arise from incorrect rear wheel camber and toe settings?

The issue that arises from incorrect rear wheel camber and toe settings relates primarily to bump steer. Bump steer occurs when the suspension geometry causes a change in the toe angle of the wheel as the suspension moves up or down. This can lead to unexpected steering responses, making the vehicle difficult to control, especially when driving over bumps or uneven surfaces.

When the rear wheels have incorrect camber—a measure of the tilt of the wheel relative to the vertical axis—and toe settings—which refer to the angle of the wheels relative to the centerline of the vehicle—this can cause misalignment that alters how the vehicle handles. As the suspension travels, the altered angles can induce changes in steering that are not proportional to the driver's input, creating a situation where the vehicle may steer in an unintended direction.

While issues like increased tire wear, reduced fuel efficiency, and loss of traction can stem from improper alignment as well, the specific concern with bump steer directly relates to the dynamics of steering and handling caused by suspension design and orientation. Thus, focusing on bump steer highlights a critical performance and safety issue that can arise in vehicles with incorrect rear wheel alignment settings, particularly when assessing the handling characteristics during dynamic driving conditions.