Pneumatic tire with tread having groove area ratio

摘要

A pneumatic tire for improving steering stability performance on dry and wet road surfaces. The tire tread pattern has circumferential center main grooves, outside and inside main grooves, land sections demarcated by the main grooves, ground contact borders on both sides of the tire, and closed shoulder lug grooves. A ratio Wmax/Wout of a maximum main groove width Wmax and an outside main groove width Wout is at between 1.5 and 2.5 inclusive. A ratio Sin/Sout of a groove area ratio Sin of a region on a tire-widthwise second side of a tire centerline and a groove area ratio Sout of a region on a first side of the tire centerline is at least 1.10 and smaller than 1.25. A groove area ratio of a region on the second side of a tire-widthwise centerline of the intermediate land sections exceeds that of a region on the first side.

主权项

1. A pneumatic tire comprising:
a first side side-section arranged on an outward side when the tire is mounted to a vehicle, a second side side-section arranged on an inward side when the tire is mounted to a vehicle, and a tread section, the tread section comprising:
a plurality of circumferential main grooves extending along a circumferential direction of the tire, the plurality of circumferential main grooves including the following four main grooves:
two center main grooves provided on opposite sides of a tire centerline and arranged such that a tire-widthwise center of each of the two center main grooves is separated from the tire centerline by a distance equal to at least 8% and not more than 12% of a ground contact width;an inside main groove provided on the second side with respect to the center main grooves and arranged such that a tire-widthwise center of the inside main groove is separated from the tire centerline by a distance equal to at least 26% and not more than 32% of the ground contact width; andan outside main groove provided on the first side with respect to the center main grooves and arranged such that a tire-widthwise center of the outside main groove is separated from the tire centerline by a distance equal to at least 26% and not more than 32% of the ground contact width;a plurality of land sections that are demarcated by the circumferential main grooves and ground contact borders on both sides of the tread section and extending continuously in the circumferential direction of the tire, such that an inside land section of the land sections that is positioned on the second side with respect to the inside main groove defines an inside shoulder lug groove that extends in a widthwise direction of the tire and an outside land section of the land sections that is positioned on the first side with respect to the outside main groove defines an outside shoulder lug groove that extends in the widthwise direction of the tire; Wmax is a maximum groove width among the center main grooves and the inside main groove and Wout is a groove width of the outside main groove, such that a ratio Wmax/Wout is at least 1.5 and not larger than 2.5; a groove area ratio Sin of a region of a ground contact surface located on the second side of the tire centerline and a groove area ratio Sout of a region of the ground contact surface located on the first side of the tire centerline are set such that a ratio Sin/Sout is at least 1.10 and smaller than 1.25, and a groove area ratio of the entire ground contact surface is at least 23% and not larger than 33%; the land sections include an inside intermediate land section demarcated by the inside main groove and the center main groove positioned on the second side of the tire centerline and an outside intermediate land section demarcated by the outside main groove and the center main groove positioned on the first side of the tire centerline, each of the inside and outside intermediate land sections being provided with a plurality of slanted grooves or sipes, such that a groove area ratio of a region on the second side of a first centerline dividing the inside intermediate land section in the widthwise direction of the tire is higher than a groove area ratio of a region on the first side of the first centerline, and a groove area ratio of a region on the second side of a second centerline dividing the outside intermediate land section in the widthwise direction of the tire is higher than a groove area ratio of a region on the first side of the second centerline; and the inside shoulder lug groove has a terminal end that is closed such that the inside shoulder lug groove does not communicate with the inside main groove, and the outside shoulder lug groove has a terminal end that is closed such that the outside shoulder lug groove does not communicate with the outside main groove and wherein sipes are provided on a first side edge of the inside intermediate land section facing toward the first side and sipes are not provided on a second side edge of the inside intermediate land section facing toward the second side.