Excessive tire wear on tread shoulders is probably caused by what condition?

• A. Under inflation
• B. Over inflation
• C. Wheel misalignment
• D. Suspension wear

Answer: (A)

Excessive wear on the tread shoulders points to improper inflation. When a tire is underinflated, the contact patch becomes biased toward the edges and the sidewalls flex more, causing the outer edges of the tread to bear more load and heat up. That increased stress wears away the shoulders faster than the center. If the tire were overinflated, the center of the tread would wear more because the contact patch is narrower and bears more load there. Misalignment or suspension wear tends to create wear patterns off to one edge or in cupped irregular shapes rather than uniform shoulder wear. So underinflation best explains shoulder wear.