Tire wear results in shallower tread grooves, loss of elasticity, rubber hardening, and reduced movement of tread blocks. This can impact worn tire performance in some situations. And it accomplishes this without adversely affecting tread life. Bonding among the rubber polymer molecules and carbon black is an important factor in rubber elasticity. Tire manufacturers promote bonding in the vulcanization process by adding sulfur and applying heat to the rubber.
Sulfur bridges strengthen the tire by linking the rubber polymer molecules.
A higher grip rubber is employed for the base layer under the cap. So, as the tread wears down, the higher-grip rubber underneath becomes exposed. This minimizes the effect of wear on worn tire performance and helps maintain more consistent handling. It also helps to prevent the increase in noise that tends to occur as the tread wears away. The company also produces Firestone air springs, roofing materials, synthetic rubber, and industrial fibers and textiles.