Tire Anatomy 101
Tires are composed of many different elements, which we will discuss here. For further breakdown of these definitions, view our Tire Glossary.
The Bead: A loop of high-strength steel cable coated in rubber that allows for the tire to remain “seated” on the rim.
The Sidewall: You guessed it! This is the side wall of the tire. You will typically find manufacturer markings on the sidewall, such as tire size, type, and air pressure specifications. They also serve to protect cord plies.
The Tread: Like the treads on the soles of your sneakers, this is the ridged rubber surface where the tire touches the road. It provides traction, stability, and strength to your tire, and its level of wear is an indicator of whether it’s time to replace the tire or not.
The Belts: Between the tread and the plies lie the belts, which are layers of steel, rayon, and fiberglass, all coated in rubber that criss-cross to hold the plies in place. Belts serve the crucial functions of providing resistance against punctures and helping the treads remain flat, keeping maximum contact and traction with the pavement.
The Body: This is a term for the tire, itself, which is composed of many intertwined layers of plies. Plies are coated in rubber and run perpendicular to the tire’s tread. By bonding together with plenty of other plies and belts, they help to seal air within the tire and provide strength and resilience in the face of road damage.
The Inner Liner: Air, when left to its own devices, would seek to escape the tire. The inner liner is the innermost layer within a tubeless tire that helps keep the air in place and the tire pressure constant.
The Sipes: Look closer. Within the tire treads are secondary, smaller treads whose role is to improve traction over a variety of challenging road conditions, including sand, dirty, wet pavement, snow, and ice. These special treads are the sipes.