What is the term for the part of the tire that contacts the wheel?

The part of the tire that contacts the wheel is referred to as the bead. The bead is crucial because it ensures a secure fit between the tire and the wheel rim, allowing the tire to hold air properly and function effectively. It is designed to maintain the integrity of the tire's structure, especially under pressure from inflation and the stresses of driving.

The lip refers to the outer edge of the wheel that may serve as a decorative or protective feature but does not specifically refer to any functional part of the tire’s connection to the wheel. The shoulder is a portion of the tire that connects the tread to the sidewall and aids in handling and stability but is not involved in the attachment to the wheel. The tread is the outer part of the tire designed for traction upon various surfaces but does not play a role in the contact point with the wheel itself. Therefore, the correct terminology for the part of the tire that secures it to the wheel is the bead.