The rear tires have a diagonal wear pattern. Which of the following is the most likely cause?

When rear tires exhibit a diagonal wear pattern, it is typically indicative of an issue related to the alignment of the wheels, particularly the rear toe. Rear toe refers to the angle at which the rear tires are aligned in relation to the centerline of the vehicle. If the rear toe is out of specification—meaning the tires are either too far apart or too close together—the contact patch of the tires with the road surface can be uneven. This misalignment causes the tires to wear in a diagonal fashion rather than evenly across the tread.

While rear camber also affects tire wear, it usually leads to uneven wear on one side of the tire—either the inner or outer edge—rather than a diagonal pattern. Front camber impacts the front tires and does not directly influence rear tire wear patterns. Similarly, front caster is a suspension angle that primarily affects the steering of the front wheels and has little to no effect on rear tire wear.

In summary, the most likely cause of a diagonal wear pattern in the rear tires is an issue with rear toe, as it directly influences how the tires make contact with the road, leading to uneven wear across the tread surface.