What Is Secondary Rubber on Tires? The secondary rubber is located under the primary tread of the tires. In other words, they are the sub-tread located under the tire's tread pattern. Usually, the tire secondary rubber does not offer the same traction as it is used to strengthen the tire and its performance.

Tire beads hold the tire to the rim, or the outer edge of the wheel. They're made of copper, brass, or bronze-plated high tensile steel wires wound into a rubber band.

Tread: Provides traction and turning grip for the tire and is designed to resist wear, abrasion, and heat. Ribs: A pattern of tread features aligned around the circumference of the tire. Usually, there are multiple ribs across the tread area of a tire. Shoulder: The area of the tire where the tread and sidewall meet.

Plies – “E” The last letter in a standard tire size indicates the number of layers used in the construction of the tire. If there is no letter, the tire has the standard 4 plies. A “C” indicates 6 plies, a “D” indicates 8 plies, and an “E” indicates 10 plies.