A heavy duty tire 2 includes a tread 4 including a tread surface 6 and having a crown portion Cr and shoulder land portions 22. A circumferential narrow groove 26 is formed on the crown portion Cr and includes a body portion 28 and an enlarged width portion 30. The tread surface 6 includes a land surface 10C of the crown portion Cr and land surfaces 10S of the shoulder land portions 22. A contour of the land surface 10C is represented by an arc. A contour of each land surface 10S is represented by an arc or a straight line. A ratio of a distance in a radial direction from an equator to an end of the tread surface 6 to a distance in the radial direction from the equator to a reference end of the tread surface 6 is not less than 0.60 and not greater than 1.70.
