SOS Mechanic Certification Practice Exam

The excessive wear on a tire's outer edge is commonly associated with an excessive camber angle. Camber refers to the tilt of the wheel from vertical when viewed from the front of the vehicle. When a tire has a significant negative camber, the top of the tire tilts inward towards the vehicle and the bottom of the tire tilts outward. This causes the outer edge of the tire to make more contact with the road, resulting in uneven wear. In contrast, other factors like under-inflation can lead to more wear on the edges of the tire as well, but it tends to wear more evenly across the tread, making outer edge wear less pronounced. Over-allignment terminology can be misleading in this context; proper alignment (which includes camber, toe, and caster adjustments) should not cause excessive wear if performed correctly. Lastly, using an improper tire size can lead to a range of performance issues but does not specifically cause outer edge wear directly in the context of tire alignment angles.