What is the difference between Primacy 4 and Primacy 4St?

[NatalieLynn]

Compared to the Primacy 4, the Michelin Primacy 4St adopts a new tread pattern design and a new rubber compound, improving wet braking performance and rolling resistance for both new and worn tires. Functions of tires: Mainly include dry grip, hydroplaning resistance, providing comfort, reducing driving noise, impact resistance, wet grip, load capacity, handling capability, average wear, and mileage. Cross-sectional structure of tires: Generally can be divided into four parts: tread, shoulder, sidewall, and bead. Each part has its own function. The tread mainly contacts the ground, the shoulder and sidewall provide support, and the bead contacts the wheel rim to provide sealing. Internal composition of tires: The interior of the tire is composed of multiple layers of different materials, including tread pattern, overlay, steel belt layer, stress absorption rubber strip, carcass ply layer, and inner liner.