The greatest heat will be generated in a tire that is operated ________.

• A. Over-inflated
• B. Under-inflated
• C. Properly inflated
• D. Flat

Answer: (B)

Heat in a tire mainly comes from energy lost as the tire deforms while it rolls. When a tire is under-inflated, the load spreads over a larger contact patch and the tread and sidewalls flex more to keep the tire in contact with the road. This extra deformation and rubbing convert more of the motion energy into heat, so the tire heats up faster than it would at proper inflation. Proper inflation minimizes unnecessary bending and keeps rolling resistance lower, while over-inflation reduces the contact patch and the associated flexing, though it brings other problems. A flat tire involves extreme irregular contact and localized heating, but it’s not normal operation. So the greatest heat comes from operating with the tire under-inflated.