Pneumatic tire with tread having center sipes and middle sipes

A pneumatic tire comprising:

• a tread portion provided with a pair of circumferentially and continuously extending center main grooves on both sides of a tire equator to define a center portion therebetween, a pair of circumferentially and continuously extending shoulder main grooves arranged axially outside the center main grooves to define a middle portion between the center main groove and the shoulder main groove on each side of the tire equator, and a plurality of middle lateral grooves to divide the middle portion into a middle block row including a plurality of middle blocks;
• each center main groove extending in a zigzag manner including a plurality of inclined long sides and a plurality of inclined short sides, which are alternately arranged in a circumferential direction of the tire;
• each of the inclined long sides comprising a main part having a substantially constant groove width and a sub part having a groove width larger than that of the main part so as to form an L-shape to protrude axially inward of the tire, each of the inclined long sides and the inclined short sides defined by a first boundary and a second boundary, wherein the first boundary is a line that connects between an axially innermost point (a1) of an axially inner groove edge (10x) of the center main groove and an axially innermost point (a2) of an axially outer groove edge (10y) of the center main groove, and wherein the second boundary is a line that connects between an axially outermost point (a3) of the axially inner groove edge (10x) of the center main groove and an axially outermost point (a4) of the axially outer groove edge (10y) of the center main groove;
• the center portion being provided with at least six axially extending center sipes within a circumferential region corresponding to a pitch of circumferentially adjacent middle lateral grooves;
• and
• each middle block having a circumferential length in a range of from 85% to 95% with respect to the pitch, and being provided with at least one axially extending middle sipe, wherein the number of middle sipe on each middle block is five or less.