Heavy duty pneumatic tire

A heavy duty pneumatic tire comprises a tread portion provided with a crown main groove and a middle axial groove. The middle axial groove extends axially outwardly from its axially inner end axially outwardly spaced apart from the crown main groove and inclines with respect to the tire circumferential direction at an angle of from 45 to 75 degrees. The shortest distance between the axially inner end of the middle axial groove and the crown main groove is 1.3 to 2.5 % of the tread width. In a cross section along the widthwise center line of the middle axial groove, an end wall of the axially inner end is inclined at an angle 0 to 50 degrees with respect to the normal direction to the tread from the radially outer edge of the end wall toward the groove bottom, and a corner between the end wall and the groove bottom is chamfered by an arc having a radius of curvature of 1 to 10 mm. The middle axial groove has a depth of 20 to 80 % of the depth of the crown main groove.