What is a key indicator of tire security that must be present during inspection?

The presence of no distortion of bolt holes during the inspection is a key indicator of tire security because it directly relates to how securely the tire is mounted to the wheel. Correctly installed tires should have bolt holes that maintain their shape and integrity. Distortion of these bolt holes can indicate that the wheel is experiencing undue stress or that there may be issues such as improper installation, damage, or wear which could lead to the tire not being securely fastened. A secure tire is crucial for safe vehicle operation, as it minimizes the risk of tire blowouts or detachment while driving, both of which can lead to dangerous situations on the road.

While other options may describe potential issues related to tire or wheel safety, they do not specifically indicate the firmness of the tire's attachment to the vehicle. For instance, a loose fit on the rim poses a clear safety risk, as does the presence of bent or damaged structures. Excessive grease accumulation can also impair performance, but none of these factors focus on the critical element of how well the tire is secured to the rim, which is best assessed by examining the condition of the bolt holes. Thus, ensuring there is no distortion present is essential for confirming that the tire is secure.