Why is it unsafe to operate with a large diameter difference between dual tires?

• A. It can improve stability
• B. It can cause uneven wear and risk of tire failure
• C. It has no impact
• D. It reduces fuel efficiency only

Answer: (B)

When dual tires are used, both tires should rotate at the same speed and carry the load evenly. A large diameter difference means the two tires don’t roll together, so they scrub against the road at different rates. This creates uneven wear and uneven load sharing, which stresses the belts and sidewalls and raises the risk of tire failure, especially under heavy load or high heat. The mismatch can also make handling feel unpredictable, with vibrations and steering instability during braking or cornering. Keeping dual tires matched in diameter helps ensure even wear, reliable load distribution, and stable, predictable handling.