What is the effect of excessive positive camber on tire tread wear?

Excessive positive camber primarily affects tire tread wear by causing cupping or scalloping across the tire tread. When the camber angle is too positive, the tire's contact patch with the road becomes imbalanced. The outer edge of the tire makes more contact with the road than the inner edge, leading to uneven distribution of forces. As a result, the outer edges will wear more quickly and unevenly, creating a pattern of dips or high and low spots, which is known as cupping.

This type of tread wear can also lead to noise and vibration while driving, indicating a problem with the suspension setup. However, it is the specific wear pattern known as cupping that is directly related to excessive positive camber, making it the correct choice in this scenario.