Pneumatic tire

A pneumatic tire comprising at least one pair of parallel annular beads (3), at least one carcass ply (5), a tread (7), and first and second sidewalls (9) disposed between the tread (7) and one of the at least one pair of beads (3) is disclosed. The tread (7) comprises tread blocks and/or tread ribs (12), wherein the tread blocks and/or the tread ribs (12) comprise sipes (13) extending essentially in an axial direction of the tire (1), the sipes (13) comprising: (i) a radially upper portion (15, 25) essentially aligned with the radial direction of the tire (1) and a radially lower portion (17, 29) having a lower end inclined in the direction of rotation of the tire (1), wherein the upper portion (15, 25) extends radially inwardly from the surface of the respective tread block of tread rib surface and wherein the lower portion (17, 29) extends to the bottom of the sipe (13); or (ii) a radially upper portion (15, 25) essentially aligned with the radial direction of the tire (1), a middle portion (27) having a lower end inclined in the direction of rotation of the tire, and a radially lower portion (29) essentially aligned with the radial direction of the tire, wherein the middle portion (27) is located between the upper portion (15, 25) and the lower portion (29).