Which of the following is the most likely cause of tires which are worn in the center of the tread?

Worn tires in the center of the tread are primarily indicative of overinflation. When a tire is overinflated, the increased air pressure pushes the center of the tread outward, causing it to make more contact with the road surface than the edges. This uneven distribution of contact leads to faster wear in the center compared to the outer edges. Consequently, this wear pattern is clearly visible and is a crucial diagnostic sign for technicians assessing tire health.

In contrast, underinflation usually results in the edges of the tires wearing more than the center, as the tire bulges outward and reduces contact area in the center. Positive caster and positive camber angles can affect tire wear as well, but they are less directly related to a center tread wear pattern compared to issues with tire pressure.