A tire comprising: a first circumferential groove arranged on a tread center portion; two second circumferential grooves adjacent to both sides of the first circumferential groove in a tire width direction; a plurality of lateral grooves opened to the first circumferential groove and the second circumferential groove; and a plurality of blocks (31, 41, 51, 61) on a tread portion partitioned by the first circumferential groove, the two second circumferential grooves, and the plurality of lateral grooves, an air flow in a direction opposite to a tire rotating direction being generated in the first circumferential groove and the two second circumferential grooves during running of a vehicle; wherein each block of the plurality of blocks (31, 41, 51, 61) has: a first wall surface (32, 42, 52, 62) formed from a position where the lateral groove on a downstream side of the air flow is opened to the first circumferential groove, toward an upstream side of the air flow; a second wall surface (33, 43, 53, 63) formed from a position where the lateral groove on the downstream side of the air flow is opened to the second circumferential groove, toward the upstream side of the air flow; and a block corner portion (34, 44, 54, 64) formed at a position where the lateral groove on the upstream side of the air flow is opened to the first circumferential groove; and when the two blocks (31, 41, 51, 61) on the upstream side and the downstream side of the air flow adjacent in a tire circumferential direction are viewed, a virtual surface (36, 46, 56, 66) obtained by extending, on the downstream side of the air flow, the first wall surface (32, 42, 52, 62) of the block (31, 41, 51, 61) on the upstream side intersects with the block corner portion (34, 44, 54, 64) of the block (31, 41, 51, 61) on the downstream side or passes through a position in the first circumferential groove inside the block corner portion (34, 44, 54, 64) in the tire width direction; and characterized in that a groove width of each of the two second circumferential grooves gradually increases toward the downstream side of the air flow at the second wall surface (33, 43, 53, 63) of the block (31, 41, 51, 61). a first circumferential groove arranged on a tread center portion; two second circumferential grooves adjacent to both sides of the first circumferential groove in a tire width direction; a plurality of lateral grooves opened to the first circumferential groove and the second circumferential groove; and a plurality of blocks (31, 41, 51, 61) on a tread portion partitioned by the first circumferential groove, the two second circumferential grooves, and the plurality of lateral grooves, an air flow in a direction opposite to a tire rotating direction being generated in the first circumferential groove and the two second circumferential grooves during running of a vehicle; wherein each block of the plurality of blocks (31, 41, 51, 61) has: a first wall surface (32, 42, 52, 62) formed from a position where the lateral groove on a downstream side of the air flow is opened to the first circumferential groove, toward an upstream side of the air flow; a second wall surface (33, 43, 53, 63) formed from a position where the lateral groove on the downstream side of the air flow is opened to the second circumferential groove, toward the upstream side of the air flow; and a block corner portion (34, 44, 54, 64) formed at a position where the lateral groove on the upstream side of the air flow is opened to the first circumferential groove; and a first wall surface (32, 42, 52, 62) formed from a position where the lateral groove on a downstream side of the air flow is opened to the first circumferential groove, toward an upstream side of the air flow; a second wall surface (33, 43, 53, 63) formed from a position where the lateral groove on the downstream side of the air flow is opened to the second circumferential groove, toward the upstream side of the air flow; and a block corner portion (34, 44, 54, 64) formed at a position where the lateral groove on the upstream side of the air flow is opened to the first circumferential groove; and when the two blocks (31, 41, 51, 61) on the upstream side and the downstream side of the air flow adjacent in a tire circumferential direction are viewed, a virtual surface (36, 46, 56, 66) obtained by extending, on the downstream side of the air flow, the first wall surface (32, 42, 52, 62) of the block (31, 41, 51, 61) on the upstream side intersects with the block corner portion (34, 44, 54, 64) of the block (31, 41, 51, 61) on the downstream side or passes through a position in the first circumferential groove inside the block corner portion (34, 44, 54, 64) in the tire width direction; and characterized in that a groove width of each of the two second circumferential grooves gradually increases toward the downstream side of the air flow at the second wall surface (33, 43, 53, 63) of the block (31, 41, 51, 61).