Tire
A tire includes circumferential main grooves, lug grooves, and land portions defined by the circumferential main grooves and the lug grooves. The circumferential main grooves extend in a circumferential direction. The lug grooves extend in a width direction, include shoulder and center lug grooves, and have an end opening to a circumferential main groove. Narrow shallow grooves in center and shoulder land portions have an end opening to a circumferential main groove and have a groove depth of 10-40% of a circumferential main groove depth. The shoulder lug grooves are on an outer side of a shoulder main groove in the width direction and have an end opening to the shoulder main groove. The center lug grooves are between the center and shoulder main grooves, have both ends opening to circumferential main grooves, and have a minimum width wider than a minimum width of the shoulder lug groove.
1. A tire, comprising:
three circumferential main grooves disposed side by side in a tire width direction and extending in a tire circumferential direction;
lug grooves extending in the tire width direction, each of the lug grooves having at least one end opening to one of the circumferential main grooves;
land portions defined by the circumferential main grooves and the lug grooves,
among the three circumferential main grooves, the circumferential main groove disposed at a center in the tire width direction is defined as a center main groove and the circumferential main grooves disposed on both sides of the center main groove in the tire width direction are defined as shoulder main grooves, and among the land portions, the land portions disposed on an inner side of the shoulder main grooves in the tire width direction are defined as center land portions and the land portions disposed on an outer side of the shoulder main grooves in the tire width direction are defined as shoulder land portions, narrow shallow grooves being formed in the center land portions and the shoulder land portions, each of the narrow shallow grooves having at least one end opening to the circumferential main groove, each of the narrow shallow grooves having a groove depth Dn within a range 0.1≤(Dn/Dm)≤0.4 to a groove depth Dm of the circumferential main grooves, and
the lug grooves comprising shoulder lug grooves and center lug grooves, the shoulder lug grooves being disposed on an outer side of the shoulder main grooves in the tire width direction, each of the shoulder lug grooves having one end opening to the shoulder main grooves, the center lug grooves being disposed between the center main groove and the shoulder main grooves, each of the center lug grooves having both ends opening to the circumferential main grooves, the center lug grooves having a minimum groove width wider than a minimum groove width of the shoulder lug grooves; wherein
the center lug grooves include center lug grooves on both sides of a tire equator, the center lug grooves on both sides of the tire equator having a same direction of inclination with respect to the tire circumferential direction,
the narrow shallow grooves formed in the center land portions have both ends opening to the circumferential main grooves,
the narrow shallow grooves formed in the shoulder land portions have one end opening to one of the circumferential main grooves and another end terminating within the shoulder land portions,
an inclination direction of the narrow shallow grooves in the tire circumferential direction with respect to the tire width direction is a direction identical to an inclination direction of the lug grooves in the tire circumferential direction with respect to the tire width direction, and
the lug grooves define the land portions in which the narrow shallow grooves are formed.
2. The tire according to claim 1 , wherein the narrow shallow grooves are formed in a zigzag shape in which the narrow shallow grooves bend at three or more locations while extending in the tire width direction.
3. The tire according to claim 1 , wherein the narrow shallow grooves formed in the center land portions and the shoulder land portions adjacent to one another via the shoulder main grooves are disposed to be displaced in the tire circumferential direction without having portions where positions in the tire circumferential direction become identical positions.
4. The tire according to claim 1 , wherein the narrow shallow grooves formed in the shoulder land portions have a length in the tire width direction within a range of from not less than 40% to not greater than 70% of a width of the shoulder land portions in the tire width direction.
5. The tire according to claim 1 , wherein the center lug grooves have a groove depth Dc within a range 0.50≤(Dc/Dm)≤0.90 to the groove depth Dm of the circumferential main grooves, and the shoulder lug grooves have a groove depth Ds within a range 0.05≤(Ds/Dm)≤0.15 to the groove depth Dm of the circumferential main grooves.
6. The tire according to claim 1 , wherein the narrow shallow grooves are connected to a narrow shallow groove notch portion to open to the circumferential main grooves via the narrow shallow groove notch portion, the narrow shallow groove notch portion is a notch opening to the circumferential main grooves, and the narrow shallow groove notch portion is formed to have a width that widens from a narrow shallow groove side to a circumferential main groove side.
7. The tire according to claim 1 , wherein a groove area ratio of a range between center lines of the shoulder main grooves on both sides in the tire width direction is two times or more of a groove area ratio on an outer side in the tire width direction of the center lines of the shoulder main grooves.
8. The tire according to claim 1 , wherein the center land portions have a width in the tire width direction within a range of from not less than 15% to not greater than 20% of a development width of a tread portion, and the shoulder land portions have a width in the tire width direction within a range of from not less than 20% to not greater than 25% of the development width.
9. The tire according to claim 1 , wherein in the narrow shallow grooves, long portions and short portions are alternately connected, and bent portions forming connecting portions between the long portions and the short portions are within a range of from not less than 3 locations to not greater than 10 locations.
10. The tire according to claim 1 , wherein a cross-sectional area of the circumferential main grooves in a cross-sectional view viewed in an extension direction of the circumferential main grooves satisfies a relationship (SL/SU)<0.5 between a cross-sectional area SL on a groove bottom side of the circumferential main grooves and a cross-sectional area SU on a tread contact surface side demarcated by a position ½ of a groove depth of the circumferential main grooves.
11. The tire according to claim 2 , wherein the narrow shallow grooves formed in the center land portions and the shoulder land portions adjacent to one another via the shoulder main grooves are disposed to be displaced in the tire circumferential direction without having portions where positions in the tire circumferential direction become identical positions.
12. The tire according to claim 2 , wherein the narrow shallow grooves formed in the shoulder land portions have a length in the tire width direction within a range of from not less than 40% to not greater than 70% of a width of the shoulder land portions in the tire width direction.
13. The tire according to claim 12 , wherein the center lug grooves have a groove depth Dc within a range 0.50≤(Dc/Dm)≤0.90 to the groove depth Dm of the circumferential main grooves, and the shoulder lug grooves have a groove depth Ds within a range 0.05≤(Ds/Dm)≤0.15 to the groove depth Dm of the circumferential main grooves.
14. The tire according to claim 13 , wherein the narrow shallow grooves are connected to a narrow shallow groove notch portion to open to the circumferential main grooves via the narrow shallow groove notch portion, the narrow shallow groove notch portion is a notch opening to the circumferential main grooves, and the narrow shallow groove notch portion is formed to have a width that widens from a narrow shallow groove side to a circumferential main groove side.
15. The tire according to claim 14 , wherein a groove area ratio of a range between center lines of the shoulder main grooves on both sides in the tire width direction is two times or more of a groove area ratio on an outer side in the tire width direction of the center lines of the shoulder main grooves.
16. The tire according to claim 15 , wherein the center land portions have a width in the tire width direction within a range of from not less than 15% to not greater than 20% of a development width of a tread portion, and the shoulder land portions have a width in the tire width direction within a range of from not less than 20% to not greater than 25% of the development width.
17. The tire according to claim 1 , wherein each of the narrow shallow grooves has a width of from 2.0 to 3.0 mm.
18. The tire according to claim 7 , wherein the groove area ratio of the range between center lines of the shoulder main grooves on both sides in the tire width direction is less than three times the groove area ratio on the outer side in the tire width direction of the center lines of the shoulder main grooves.
19. A tire, comprising:
three circumferential main grooves disposed side by side in a tire width direction and extending in a tire circumferential direction;
lug grooves extending in the tire width direction, each of the lug grooves having at least one end opening to one of the circumferential main grooves;
land portions defined by the circumferential main grooves and the lug grooves,
among the three circumferential main grooves, the circumferential main groove disposed at a center in the tire width direction is defined as a center main groove and the circumferential main grooves disposed on both sides of the center main groove in the tire width direction are defined as shoulder main grooves, and among the land portions, the land portions disposed on an inner side of the shoulder main grooves in the tire width direction are defined as center land portions and the land portions disposed on an outer side of the shoulder main grooves in the tire width direction are defined as shoulder land portions, narrow shallow grooves being formed in the center land portions and the shoulder land portions, each of the narrow shallow grooves having at least one end opening to the circumferential main groove, each of the narrow shallow grooves having a groove depth Dn within a range 0.1≤(Dn/Dm)≤0.4 to a groove depth Dm of the circumferential main grooves, and
the lug grooves comprising shoulder lug grooves and center lug grooves, the shoulder lug grooves being disposed on an outer side of the shoulder main grooves in the tire width direction, each of the shoulder lug grooves having one end opening to the shoulder main grooves, the center lug grooves being disposed between the center main groove and the shoulder main grooves, each of the center lug grooves having both ends opening to the circumferential main grooves, the center lug grooves having a minimum groove width wider than a minimum groove width of the shoulder lug grooves; wherein
the center lug grooves include center lug grooves on both sides of a tire equator, the center lug grooves on both sides of the tire equator having a same direction of inclination with respect to the tire circumferential direction,
the narrow shallow grooves formed in the center land portions have both ends opening to the circumferential main grooves,
the narrow shallow grooves formed in the shoulder land portions have one end opening to one of the circumferential main grooves and another end terminating within the shoulder land portions,
the center land portions have a width in the tire width direction within a range of from not less than 15% to not greater than 20% of a development width of a tread portion, and
the shoulder land portions have a width in the tire width direction within a range of from not less than 20% to not greater than 25% of the development width.