Pneumatic tire with tread having subgrooves and sipes.
U.S. patent: 8,763,659
Issued: July 1,2014
Inventors: Kazuya Ishiguro and Yoshifumi Koishikawa
Assigned: Yokohama Rubber
Key statement: Five land portions on tread surface are demarcated by four main grooves that extend in a tire circumferential direction TC. The five land portions include a center land portion between the first main grooves, two middle land portions between the first main grooves and the second main grooves, and two shoulder land portions located toward the outside of the second main grooves in the tire width direction, and subgrooves and sipes are formed on the land portions. The total groove surface area ratios of the sub-grooves and the sipes in the land portions are different in the center land portion and the shoulder land portion as compared to the middle land portion, with the total groove surface area ratio being lower in the center land portion and the shoulder land portion and being higher in the middle land portion.