| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent a pneumatic tire for heavy load from developing cracks at the bottom of the small grooves thereof. SOLUTION: A belt 3, tread rubber and a plurality of main grooves extending in a circumferential direction are disposed. A small groove 10 which opens at the side surface and extends substantially in the circumferential direction is disposed outside the belt 3 in the axial direction and also opens at the position separated in the range of 20 to 150% of the depth of the main groove toward the inside in the radial direction from the effective roadholding end of the tread along the contour of the above described side surface in the groove width of 5 to 75% of the width of the main groove and is shaped like a letter V in the cross section. The bottom of the small groove is at the position of 0.5 to 10% of roadholding width of the tread inside in the axial direction from the above described roadholding end and at the position of 20 to 180% of the depth of the main groove inside in the radial direction from the above described roadholding end. The tread rubber comprises two upper and lower laminated rubber layers 8, 9 which are different in elasticity and has the rubber layer at the bottom of the small groove 10 which is positioned at the tread surface side and of 1.0mm or more in thickness. |
