Pneumatic tire with tread having narrow groove

1. A pneumatic tire comprising:

a shoulder land portion extending in a tire circumferential direction on a tread surface; and

a narrow groove extending in the tire circumferential direction on the shoulder land portion,

wherein dimples are arranged in a staggered manner with respect to the tire circumferential direction while overlapping with each other as seen in a depth direction of the narrow groove, and the dimples are arranged on only a groove wall in an inner side in a tire width direction of the narrow groove, and a plurality of rows of dimples are formed along the tire circumferential direction,

wherein the groove wall on an outer side in a tire width direction is a flat wall surface, and

wherein the groove wall on the inner side in the tire width direction other than the dimples is a flat wall surface.

2. The pneumatic tire as claimed in claim 1 , wherein the dimples in the adjacent dimple rows overlap with each other as seen in the tire circumferential direction.

3. The pneumatic tire as claimed in claim 1 , wherein the dimple rows are equal to or more than three rows.

4. The pneumatic tire as claimed in claim 1 , wherein the groove wall between the dimples is formed as a flat surface.

5. The pneumatic tire as claimed in claim 1 , wherein an opening of the dimple is a rhomboid shape having round corners.

6. The pneumatic tire as claimed in claim 1 , wherein the dimples in adjacent rows are staggered, and the dimples in adjacent rows overlap when viewed in the depth direction (DD) and when viewed in the circumferential direction (CD).

7. The pneumatic tire as claimed in claim 1 , wherein a magnitude D 2 in the depth direction (DD) of the dimple is 3 to 5 mm, and a distance D 3 between two of the dimples is 1 mm or more.