A pneumatic tire according to the present invention improves wet performance.The pneumatic tire has a tread surface 1. A first main groove 2 extending in the circumferential direction TC of the tire is provided in the tread surface 1. First lateral grooves 7 extending from the first main groove 2 outward in the widthwise direction of the tire beyond one ground contact end TX1 of the tire are disposed at prescribed intervals in the circumferential direction TC of the tire. Blocks 8 are defined by the first main groove 2 and the first lateral grooves 7. The first lateral grooves 7 comprise inner groove portions 7A and outer groove portions 7B. The inner groove portions 7A extend with their widths gradually increasing from the first main groove 2 outward in the widthwise direction of the tire to midways of the first lateral grooves 7. The outer groove portions 7B extend with their widths gradually decreasing from the gradually increasing inner groove portions 7A outward in the widthwise direction of the tire beyond the one ground contact end TX1 of the tire. A circumferential narrow groove 5 which extends in the circumferential direction TC of the tire and is less in width than the first main groove 2 is disposed at boundary positions between the inner groove portions 7A and the outer groove portions 7B.