Pneumatic tire with groove

A tire comprising a tread portion for contacting the ground and a pair of opposing sidewall portions,

• the tread portion extending between a pair of shoulders and having an equatorial region in between, the sidewall portions extending essentially in a radial direction from the shoulders,
• wherein the tread portion comprises next to the shoulder at least one circumferential groove extending from a groove bottom toward the tread portion, the circumferential groove forming a recessed rib, the recessed rib located on the side of the circumferential groove farther away from the equatorial region, the recessed rib has a radially outer width,
• wherein said circumferential groove has adjacent groove walls with a first groove wall facing away from the equatorial region and a second groove wall facing towards the equatorial region,
• wherein the second groove wall comprises a protruding portion protruding outwardly away from the equatorial region, the protruding portion comprising two linear diverging regions and in between the diverging regions a non-diverging region,
• wherein the diverging regions on the second groove wall are non-parallel to the first groove wall,
• wherein the non-diverging region on the second groove wall is parallel to the first groove wall, the recessed rib has a radially inner width at the non-diverging region,
• wherein a form of a bottom of the groove comprises a semicircle arc that transitions to one of the linear diverging regions,
• wherein the recessed rib has a groove bottom width at the groove bottom, the radially inner width being less than both the radially outer width and the groove bottom width to change a concentration of strain magnitude at the groove bottom,
• wherein a sum of a radial extension of the diverging regions is between 25% to 45% of the radial extension of the protruding portion,
• wherein the protruding portion is only present on the recessed rib.