A pneumatic tire comprising: a tread portion extending in a tire circumferential direction and constituting an annular shape; a pair of sidewall portions disposed on both sides of the tread portion; and a pair of bead portions disposed inward in a tire radial direction of the sidewall portions; the tread portion comprising five main grooves extending in the tire circumferential direction and six rows of ribs extending in the tire circumferential direction and partitioned by the main grooves; the ribs being constituted by a pair of center ribs positioned on a tire equatorial plane side, a pair of intermediate ribs positioned outward of each of the center ribs, and a pair of shoulder ribs positioned outward of each of the intermediate ribs, and a plurality of first narrow grooves extending in a tire width direction being formed in each of the center ribs and the intermediate ribs so as to form a connection between the main grooves; characterised in that the tread portion further comprises a plurality of second narrow grooves extending in the tire circumferential direction being formed in each of the center ribs and the intermediate ribs so as to connect neighboring first narrow grooves; a plurality of first sipes being formed in each edge portion, adjacent to the main groove, of the center ribs, the intermediate ribs, and the shoulder ribs; an interval Pg 1 in the tire circumferential direction between the first narrow grooves being from 20 mm to 60 mm; an interval Ps 1 in the tire circumferential direction between the first sipes being from 15% to 45% of the interval Pg 1 of the first narrow groove; a ratio Wa/TDW of a width Wa of the center ribs to a development width TDW of the tread portion being from 0.08 to 0.18; a ratio Wb/TDW of a width Wb of the intermediate ribs to the development width TDW of the tread portion being from 0.08 to 0.18; and a ratio Wc/Wa of a width Wc of the shoulder ribs to the width Wa of the center ribs being from 1.20 to 1.30. a tread portion extending in a tire circumferential direction and constituting an annular shape; a pair of sidewall portions disposed on both sides of the tread portion; and a pair of bead portions disposed inward in a tire radial direction of the sidewall portions; the tread portion comprising five main grooves extending in the tire circumferential direction and six rows of ribs extending in the tire circumferential direction and partitioned by the main grooves; the ribs being constituted by a pair of center ribs positioned on a tire equatorial plane side, a pair of intermediate ribs positioned outward of each of the center ribs, and a pair of shoulder ribs positioned outward of each of the intermediate ribs, and a plurality of first narrow grooves extending in a tire width direction being formed in each of the center ribs and the intermediate ribs so as to form a connection between the main grooves; characterised in that the tread portion further comprises a plurality of second narrow grooves extending in the tire circumferential direction being formed in each of the center ribs and the intermediate ribs so as to connect neighboring first narrow grooves; a plurality of first sipes being formed in each edge portion, adjacent to the main groove, of the center ribs, the intermediate ribs, and the shoulder ribs; an interval Pg 1 in the tire circumferential direction between the first narrow grooves being from 20 mm to 60 mm; an interval Ps 1 in the tire circumferential direction between the first sipes being from 15% to 45% of the interval Pg 1 of the first narrow groove; a ratio Wa/TDW of a width Wa of the center ribs to a development width TDW of the tread portion being from 0.08 to 0.18; a ratio Wb/TDW of a width Wb of the intermediate ribs to the development width TDW of the tread portion being from 0.08 to 0.18; and a ratio Wc/Wa of a width Wc of the shoulder ribs to the width Wa of the center ribs being from 1.20 to 1.30.