Bridgestone/firestone, Inc.

Michael J Ferraco

Bill J Wallet

David M Reep

Shawn L Copeland

Yukio Yamakawa

Yaso Himuro

A tire tread has a total of four circumferential ribs and three circumferential grooves. The four ribs include two intermediate ribs and two outer ribs, and the three grooves include a center groove and two outer grooves. The two intermediate ribs are between the center groove and the two outer grooves, and the outer ribs are on the opposite sides of the outer grooves from the intermediate ribs. Rib cross slots and cross sipes extend outwardly from the outer grooves into the intermediate and outer ribs in herringbone patterns. The cross slots and cross sipes extend less than the full width of the ribs to provide the intermediate ribs with circumferential inner portions adjacent the center groove that are devoid of cross slots. These circumferential inner portions of the intermediate ribs have a plurality of circumferentially-spaced cross sipes that do not intersect the center groove. The rib cross slots are circumferentially-spaced a plurality of different distances to define a plurality of rib blocks having different lengths. Shorter rib blocks have a single cross sipe and longer rib blocks have double cross sipes. Shoulder cross slots intermediate the cross slots in the outer ribs overlap the outer rib cross slots by 25-35% of the outer rib cross slot length. The rib and shoulder cross slots have sloping closed end surfaces that intersect the outer surface of the tread at an angle of 35-42.degree.. Shoulder and outer rib cross sipes that are positioned opposite from the rib and shoulder cross slots do not intersect or overlap the rib or shoulder cross slots.

Growing community of inventors

Akron, OH, United States of America

Michael J Ferraco