Michelin Pilot Sport "Rib" Max Performance tires have been developed for original equipment use on late model Porsche cars. They are a straight rib tread design derivative of Michelin's Pilot Sport tire line. As Porsche original equipment tires, designated "N-1" (18-inch sizes) and "N-2" (17-inch sizes), Pilot Sport "Rib" tires are designed to offer enhanced acoustic comfort and refined road manners while providing the driver with exceptional feedback and progressive handling. On the outside, the Michelin Pilot Sport "Rib" tires combine some of the construction technologies of the standard Pilot Sport with the straight rib type tread design of Michelin's Pilot SX MXX3 tire line. The uninterrupted center ribs reduce tire noise on dry roads while they sharpen steering response and provide communicative road feel. On the inside, the tread design is supported by two belts made of high-tensile, lightweight steel cords which are further reinforced by size-optimized, spirally wrapped nylon cord utilizing Michelin's BAZ (Banded At Zero) Technology to improve steering response and resist distortion while they enhance ride quality and high speed durability.Ultra-reinforced sidewalls promote fast steering response and powerful cornering, while Michelin's cable beads help maintain the shape of a running tire for better tire/wheel uniformity.