Pneumatic tire
A pneumatic tire includes at least four circumferential main grooves extending in the tire circumferential direction; and at least five rows of land portions including a center land portion, a pair of second land portions, and a pair of shoulder land portions, which are defined by the circumferential main grooves. Additionally, at least one row of the second land portions is provided with a plurality of lug grooves penetrating through the second land portion in the tire width direction, and a plurality of blocks defined by the plurality of lug grooves. Moreover, the plurality of blocks include one of the circumferential narrow grooves, respectively, which penetrates through the blocks in the tire circumferential direction.
1. A pneumatic tire, comprising:
at least four circumferential main grooves extending in a tire circumferential direction; and
a least five land portions including a center land portion, a pair of second land portions, and a pair of shoulder land portions that are defined by the circumferential main grooves;
at least one second land portion of the pair of second land portions including a plurality of lug grooves penetrating through the at least one second land portion in a tire width direction, and a plurality of blocks defined by the plurality of lug grooves;
the plurality of blocks each including one circumferential narrow groove penetrating through the block in the tire circumferential direction;
the plurality of lug grooves in the at least one second land portion each having an offset shape in which a groove center line on the tire equatorial plane side and a groove center line on the tire ground contact edge side are mutually offset at a crossing position with the circumferential narrow groove; and
offset directions of the offset shapes of a pair of lug grooves of the plurality of lug grooves adjacent to each other in the tire circumferential direction being mutually different.
2. The pneumatic tire according to claim 1 , wherein:
the plurality of lug grooves each have a bent shape.
3. The pneumatic tire according to claim 1 , wherein:
blocks of the plurality of blocks adjacent to each other in the tire circumferential direction have mutually different shapes.
4. The pneumatic tire according to claim 1 , wherein:
the circumferential narrow groove has a bent shape that has an amplitude in the tire width direction.
5. The pneumatic tire according to claim 1 , wherein:
the circumferential narrow groove comprises a first inclined portion inclining at an inclination angle α 1 with respect to the tire circumferential direction, and a second inclined portion inclining at an inclination angle α 2 with respect to the tire circumferential direction, the first inclined portion and the second inclined portion being connected alternately;
the inclination angle α 1 of the first inclined portion is such that 0 degrees≤α 1 ≤15degrees; and
the inclination angle α 2 of the second inclined portion is such that 45 degrees≤α 2 ≤90 degrees.
6. The pneumatic tire according to claim 1 , wherein:
a groove width W 3 of the circumferential narrow groove is such that 1.5 mm≤W 3 ≤6.0 mm.
7. The pneumatic tire according to claim 1 , wherein:
the circumferential narrow grooves adjacent to each other in the tire circumferential direction open at mutually different positions with respect to a common lug groove of the plurality of lug grooves.
8. The pneumatic tire according to claim 1 , wherein:
crossing angles of the plurality of lug grooves in the at least one second land portion with one of the circumferential main grooves on a tire equatorial plane side of the at least one second land portion are in a range of not less than 15 degrees and not greater than 75 degrees.
9. The pneumatic tire according to claim 1 , wherein:
the plurality of lug grooves in the at least one second land portion each have an opening width on the tire equatorial plane side that is narrower than an opening width on a tire ground contact edge side.
10. The pneumatic tire according to claim 1 , wherein:
the plurality of lug grooves each comprise a raised bottom portion in a region from the circumferential narrow groove to the tire equatorial plane side.
11. The pneumatic tire according to claim 1 , wherein:
a pair of lug grooves of the plurality of lug grooves adjacent to each other in the tire circumferential direction have inclination angles inclining in a same direction with respect to the tire circumferential direction and are mutually different; and
extension lines of the groove center lines of the pair of lug grooves cross each other at an edge portion of the center land portion adjacent to the at least one second land portion.
12. The pneumatic tire according to claim 11 , wherein:
the edge portion of the center land portion comprises a notched portion in a region including a crossing point of the extension lines of the groove center lines of the pair of lug grooves.
13. The pneumatic tire according to claim 1 , wherein:
the plurality of blocks of the at least one second land portion each comprise a plurality of sipes; and
a ratio of a disposal density of the plurality of sipes in a first portion to a disposal density of the plurality of sipes in a second portion of each of the plurality of blocks divided by the circumferential narrow groove is in a range of not less than 0.8 and not greater than 1.2.
14. The pneumatic tire according to claim 1 , wherein:
the plurality of blocks of the at least one second land portion each comprise a plurality of sipes; and
a ratio of circumferential lengths of portions of each of the plurality of blocks defined by the plurality of sipes is in a range of not less than 0.8 and not greater than 1.2.
15. The pneumatic tire according to claim 1 , wherein:
the plurality of blocks each comprise a chamfered portion in a corner portion.
16. The pneumatic tire according to claim 15 , wherein:
a ridge line of the chamfered portion inclines with respect to the tire width direction.