An off-road tire (1) comprises a tread portion (2) provided with blocks (10, 11) forming a sea area (8) therearound. The sea area (8) is provided in the bottom (14) thereof with recesses (13), wherein the recesses (13) are arranged circumferentially of the tire and each extend axially of the tire, and the depth (d) of each of the recesses (13) is gradually increased towards its center (13a), whereby the enveloping power is improved.