When a tire is under inflated, which part grips the road best?

When a tire is under-inflated, the outside edges of the tire tread tend to grip the road better. This occurs because an under-inflated tire will have more surface area in contact with the road at its outer edges, leading to a larger contact patch. As the tire rolls, the outer edges, which are more flexible due to lower air pressure, can adapt to the road's surface contours better than the center of the tread, which may be lifted off the road or have reduced contact.

In contrast, the center of the tire tread typically experiences more wear and reduced grip when a tire is under-inflated, as it does not maintain the appropriate contact with the road. The inside edges of the tread often remain less engaged as well during under-inflation. The sidewall of the tire does not directly provide grip on the road but rather supports the tire structure. By understanding these dynamics, it's clear how under-inflation affects tire performance, particularly emphasizing the enhanced grip at the outside edges of the tread.