Pneumatic tire

A pneumatic tire comprising

• a tread portion provided on each side of the tire equator with an axially inner crown main groove and an axially outer shoulder main groove which extend continuously in the tire circumferential direction so that the tread portion is divided into a crown land region between the crown main grooves, a pair of middle land regions between the crown main grooves and the shoulder main grooves, and a pair of shoulder land regions between the shoulder main grooves and tread edges, wherein
• the crown land region is provided with crown axial grooves which are narrow grooves and/or sipes extending across the entire width of the crown land region and arranged in a zigzag fashion so as to divide the crown land region into a plurality of crown blocks having triangular configurations,
• the middle land regions are each provided with middle axial grooves which are narrow grooves and/or sipes extending across the entire width of the middle land region and arranged in a zigzag fashion so as to divide the middle land region into a plurality of middle blocks having triangular configurations,
• the shoulder land regions are each provided with shoulder axial grooves extending across the entire width of the shoulder land region at an angle of not less than 70 degrees with respect to the tire circumferential direction so as to divide the shoulder land region into a plurality of shoulder blocks,
• the shoulder blocks are each provided with a shoulder secondary groove extending at an angle of not more than 10 degrees with respect to the tire circumferential direction and disposed at a distance of 3 to 15 mm axially outward from the shoulder main groove so as to subdivide the shoulder block into an axially inner part and an axially outer part, and
• the outer part is provided with shoulder sipes extending at an angle of not less than 70 degrees with respect to the circumferential direction, and
• wherein:
• said shoulder secondary groove extends straight,
• said shoulder secondary groove is provided in the bottom thereof with a groove-bottom sipe extending along the shoulder secondary groove,
• the groove-bottom sipe has a width smaller than the width of the shoulder secondary groove,
• one end of the groove-bottom sipe is a closed end located at a distance of 1.0 to 8 0 mm from one circumferential end of the shoulder secondary groove, and the other end of the same groove-bottom sipe is a closed end located at a distance of 1.0 to 8.0 mm from the other circumferential end of the same shoulder secondary groove,
• between the axially inner parts of the shoulder blocks, a tie bar rising from the bottom of the shoulder axial groove therebetween is disposed,
• the axial length L6 of the tie bar is not less than 30% and not more than 100% of the axial width Ws2 of the axially inner parts, and
• said shoulder sipes in the axially outer part of the shoulder block extend from the tread edge toward the shoulder secondary groove and terminate without reaching the shoulder secondary groove.