What impact does an under-inflated tire have on a dry runway?

An under-inflated tire on a dry runway primarily increases wear on the tire's shoulder. When a tire is not inflated to the proper pressure, it causes more of the shoulder area to come into contact with the runway surface. This results in uneven wear patterns, as the tire will flex more than normal during operations. The excessive deflection means that the tire’s shoulder is subjected to more stress and heat, leading to accelerated wear.

In addition to the wear issues, an under-inflated tire may negatively impact the handling and control of the aircraft, although this question focuses specifically on tire wear. The fact that the tire is under-inflated can also lead to increased rolling resistance, which could indirectly affect performance during takeoff and landing phases, but the primary impact pertains to wear patterns.

The other options fail to accurately reflect the consequences of having an under-inflated tire. For instance, the suggestion that it increases friction and improves grip is misleading, as the loss of structural integrity and reduced contact patch can actually decrease grip. The idea that it offers better fuel efficiency is also incorrect, as under-inflation typically increases resistance and can lead to higher fuel consumption. Lastly, the notion that it does not affect performance overlooks the vital mechanical implications