A tire comprises a tread portion 2 comprising a shoulder main groove 5 extending on a side of a tread edge (Te). The shoulder main groove 5 comprises an inner groove wall 11 having an angle with respect to its tread normal line in a cross section of the shoulder main groove 5 periodically increasing and decreasing in a tire circumferential direction so that the inner groove wall 11 comprises concave wall portions 16 and convex wall portions 17 arranged alternately in the tire circumferential direction. The concave wall portions 16 are provided at inner end portions thereof in a tire axial direction with recess portions 20 locally recessed inwardly in the tire axial direction and having openings at a ground contacting surface of the tread portion 2.

A pneumatic tire is provided in the tread portion with zigzag middle main grooves 4 and shoulder main grooves 5 to define middle land regions 7 therebetween. The middle main groove is composed of alternately-arranged, oppositely-inclined long first oblique segments 11 and short second oblique segments 12. The middle land regions are provided with middle transverse grooves 20 shallower than the middle main grooves. The first oblique segments are inclined axially outwardly toward the opposite direction to the intended tire rotational direction R. The middle transverse grooves are inclined to the same direction as the first oblique segments or in parallel with the tire axial direction. The axially inner end of each of the middle transverse grooves is connected to one of the second oblique segments so as to include at least a part of an axially outwardly protruding outside corner portion 4A of the middle main groove.

A tyre includes a tread portion including a tread surface which is provided with grooves. At least one of the grooves includes a widening-width portion at least partially. The widening-width portion includes a first groove portion extending inwardly in a tyre radial direction from the tread surface, and a second groove portion located inwardly in the tyre radial direction of the first groove portion and having a groove width greater than that of the first groove portion.

The invention controls irregular wear in the shoulder land portions and reduces the occurrence of cracking in the shoulder grooves of a pneumatic tire. To that end, the groove wall surface (17a) on the shoulder land portion (19) side of the shoulder groove (17) has an inclined surface consisting of a first inclined part (171) inclined toward the equatorial plane of the tire at an inclination angle .sub.1, which is constant along the circumference of the tire, and a second inclined part (172) further inclined from the first inclined part (171) toward the equatorial plane of the tire and reaching the groove bottom (17b) of the shoulder groove (17) at an angle with respect to the first inclined part (171), which varies along the circumference of the tire. Also, the inclination angles of the first and second inclined parts (171, 172) are set such that the maximum value .sub.max and the minimum value .sub.min of the angle satisfy (Dd) (tan .sub.maxtan .sub.min)2.5 where D is the depth from the tread face to the bottom of the shoulder groove (17), d is the depth from the tread face to the boundary position between the first inclined part (171) and the second inclined part (172), .sub.max is the maximum value of the angle , and .sub.min is the minimum value of the angle .

First and second groove walls 2a and 2b of a meandering main groove 21 have an upper and lower groove wall portion, respectively. The first groove wall 2a has the lower groove wall-top edge 2ale extending in a wavy line along the tire circumferential direction in order that a minimum groove wall angle portion and a maximum groove wall angle portion appear alternately. In the first groove wall 2a, the minimum groove wall angle portion and a wide groove section, and the maximum groove wall angle portion and a narrow groove section, respectively, are located at the same position in the tire circumferential direction. The upper groove wall-top edge 2aue of the first groove wall 2a extends in a straight line, a wavy line or a zigzag line with an amplitude smaller than an amplitude of the lower groove wall-top edge 2ale of the first groove wall 2a.

First and second groove walls 2a and 2b of a meandering main groove 21 have an upper and lower groove wall portion, respectively. The first groove wall 2a has the lower groove wall-top edge 2ale extending in a wavy line along the tire circumferential direction in order that a minimum groove wall angle portion and a maximum groove wall angle portion appear alternately. In the first groove wall 2a, the minimum groove wall angle portion and a wide groove section, and the maximum groove wall angle portion and a narrow groove section, respectively, are located at the same position in the tire circumferential direction. The upper groove wall-top edge 2aue of the first groove wall 2a extends in a straight line, a wavy line or a zigzag line with an amplitude smaller than an amplitude of the lower groove wall-top edge 2ale of the first groove wall 2a.