| 摘要 |
An object of the present invention is to adequately control relationship between a cross sectional width SW and an outer diameter OD of a pneumatic radial tire for a passenger vehicle. Specifically, a ground contact surface 1 of the tread of the pneumatic radial tire for a passenger car of the present invention is provided with either, as a groove, only at least one main groove 2a extending in the tread circumferential direction or, as grooves, only the main groove 2a and at least one auxiliary groove 2b other than the main groove, wherein the auxiliary groove has a groove width≦2 mm in a tread widthwise region and a negative ratio of the main groove 2a is in the range of 12% to 20% (inclusive of 12% and 20%). |
| 主权项 |
1. A pneumatic radial tire for a passenger vehicle, having a carcass constituted of plies as radially-disposed cords and provided in a toroidal shape across a pair of bead portions, and a tread, characterized in that:
a ground contact surface of the tread of the tire is provided with either, as a groove, only at least one main groove extending in the tread circumferential direction or, as grooves, only the at least one main groove and at least one auxiliary groove other than the main groove, the auxiliary groove having a groove width 2 mm in a tread widthwise region having the center aligned with the tire equatorial plane and a width corresponding to 80% of the tread width of the ground contact surface; a negative ratio of the main groove is in the range of 12% to 20% (inclusive of 12% and 20%); a groove width of the main groove is in the range of 6 mm to 30 mm; provided that SW and OD represent cross sectional width and outer diameter of the tire, respectively, SW/OD≦0.26 when SW<165 (mm); and SW and OD satisfy a formula shown below when SW≧165 (mm):
OD≧2.135×SW+282.3, wherein provided that a land portion Z is demarcated by the main groove closest to each tread end and the borderline between the main groove and the tread end, of the tread widthwise region having the center aligned with the tire equatorial plane and a width corresponding to 80% of the tread width of the ground contact surface, following relationship formulae are satisfied in at least one of the tread-width-direction inner land portion and the land portion Z:
¼≦W1/W2≦¾; andΣW1≧W2, and wherein: W1 (mm) represents a projected length in the tread width direction of each auxiliary groove; W2 (mm) represents a width in the tread width direction of the land portion having said auxiliary groove, of at least one of said land portions; and ΣW1 represents the sum of projected lengths in the tread width direction of all auxiliary grooves disposed within one pitch in the tread circumferential direction of the auxiliary grooves. |
