| CPC B60C 11/0306 (2013.01) [B60C 2011/0346 (2013.01); B60C 2011/0353 (2013.01); B60C 2011/0365 (2013.01); B60C 2011/0372 (2013.01); B60C 2200/14 (2013.01)] | 23 Claims |
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1. A tire, comprising:
four main grooves extending in a tire circumferential direction;
a plurality of land portions defined by the four main grooves; and
the four main grooves comprising two center main grooves and two shoulder main grooves, the two center main grooves being disposed on both sides of a tire equatorial plane, the two shoulder main grooves being disposed on outer sides in a tire width direction of the two respective center main grooves,
each of the four main grooves being formed in a step shape having circumferential extending portions extending in the tire circumferential direction at positions differing in the tire width direction,
a second lug groove being disposed between one center main groove of the two center main grooves and one shoulder main groove of the two shoulder main grooves which is adjacent to the one center main groove, the second lug groove extending in the tire width direction and having both ends opening to the one center main groove and the one shoulder main groove,
a shoulder lug groove being disposed on the outer side in the tire width direction of the one shoulder main groove, the shoulder lug groove extending in the tire width direction across a ground contact edge and having one end opening to the one shoulder main groove,
inclination directions of the second lug groove and the shoulder lug groove in the tire circumferential direction with respect to the tire width direction being mutually opposite directions,
in a plurality of the second lug grooves disposed side by side in the tire circumferential direction, two types of the second lug grooves having different inclination angles with respect to the tire width direction being alternately disposed;
the second lug groove opening to the one center main groove and the one shoulder main groove opening to the circumferential extending portions located close to the second lug groove among the circumferential extending portions comprised in respective of the one center main groove and the one shoulder main groove formed in the step shapes,
the shoulder lug groove opening to the one shoulder main groove opening to the circumferential extending portion located close to the shoulder lug groove among the circumferential extending portions comprised in the one shoulder main groove formed in the step shape,
the step shape having two types of the circumferential extending portions having mutually different positions in the tire width direction and a connection portion connecting the two types of the circumferential extending portions adjacent in the tire circumferential direction,
a center line of the step shape forming a rectangular wave or a trapezoidal wave to oscillate,
the connection portion of the shoulder main groove connecting the second lug groove and the shoulder lug groove,
the second lug groove comprising a first second lug groove and a second second lug groove having mutually different inclination angles with respect to the tire width direction and disposed alternately in the tire circumferential direction, and
a relationship between a wavelength λ of the step shape of the main grooves and a pitch length P of the second lug groove being within a range 0.4≤(λ/P)≤0.6, the pitch length P of the second lug groove being a distance in the tire circumferential direction between the first second lug grooves adjacent in the tire circumferential direction.
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