Tire for heavy load that prevents center wear and river wear

A tire for heavy load with an aspect ratio of 80% or less having

• a tread part divided by four circumferential main grooves into five ribs which are a center rib extending on a tire equator, a pair of outer ribs each extending along a tread edge and a pair of intermediate ribs each extending between the center rib and the corresponding outer rib, wherein
• an outer end line in the tire axial direction of each said intermediate rib extends in the circumferential direction in zigzags,
• in a state of 5% internal pressure when the tire is mounted on a regular rim and inflated by 5% of a standard internal pressure, a distance (X) from the tire equator to a center line (Q) of said zigzagged outer end line of each said intermediate rib is in a range of 0.25 to 0.275 times the tread width (WT), and
• a single tread radius of curvature R under the state of 5% internal pressure and a difference Y=y2-y1, said difference Y=y2-y1 being the difference between an inflation amount y1 at the tire equator from the state of 5% internal pressure to a state of standard internal pressure and an inflation amount y2 at the center line (Q) of said zigzagged outer end line of each said intermediate rib from the state of 5% internal pressure to the state of standard internal pressure, satisfy the following equation:
• -0.001R+0.4 mm.ltoreq.Y.ltoreq.-0.00357R+2.4 mm.