The right rear tire has a diagonal swipe wear pattern. What is this most likely caused by?

A diagonal swipe wear pattern on a tire is primarily indicative of an issue related to toe alignment. When the toe setting is not within the manufacturer's specifications, it causes the tire to either point inward (toe-in) or outward (toe-out) relative to the vehicle's centerline. This misalignment leads to irregular tire wear, such as the diagonal swipe pattern seen on the tire.

In this situation, the tire's surface experiences uneven contact with the road, as only a portion of the tread is making proper contact at any given time. When the toe is out of adjustment, the resultant sliding action against the road surface leads to wear not just that is uneven but also specifically in a diagonal manner across the tread.

Understanding how camber (both positive and negative) affects tire wear is important, but these typically create different wear patterns. Positive camber tends to wear the outer edge while negative camber wears the inner edge, not producing the diagonal swipe seen in this scenario. Caster primarily influences the steering characteristics and stability of the vehicle but does not directly affect tire wear patterns in the way improper toe does. Hence, it is clear that the diagonal wear pattern is most closely linked to an improper toe setting.