| 摘要 |
A pneumatic tire for passenger cars, formed on its tread surface with at least one main groove extending in the circumferential direction of the tire, a number of sub-grooves extending in the widthwise direction of the tire, and a plurality of sub-main grooves extending at an angle of inclination within a range of 3 DEG to 30 DEG to the circumferential direction of the tire and to a length greater than a defined contact length of the tire, the or each main groove having a groove depth of 65% or more of the thickness of a tread rubber and a groove width which is greater than its groove depth and is within a range of 6 to 9% of a tread expansion width, each sub-main groove including such a wider or broader portion which has a groove depth of 65% or more of the thickness of the tread rubber and a groove width which is greater than its groove depth and is within a range of 3.5 to 6% of the tread expansion width, at least one protuberance being provided on each of the bottom of the main groove and the bottom of the wider or broader portion of the sub-main groove, extending along the main groove and the sub-main grooves.
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