Groove beneath sipe

A tyre, the tyre comprising:

• a tread having a tread surface for contacting ground and at least one groove-like recess therein forming a free space, the recess having a longitudinal extension A along the surface and a depth B measured in a radial direction with respect to a radial axis of the tyre from the tread surface to a radially innermost position, the recess having a first end and a second end, the ends being opposite to each other along the longitudinal extension A, wherein the free space is divided into a sipe portion opening to the tread surface and
• a groove portion located beneath and radially inwards the sipe portion, wherein in a cross sectional view transverse to the longitudinal extension A of the recess the sipe portion has a sipe contour and the groove portion has a groove contour with a longitudinal axis (X′) and an extent E between an upper end of the groove contour and a lower end of the groove contour, wherein a corresponding width of the groove contour has at least one local maximum width Wg at a height H of the groove contour in the direction of this longitudinal axis, wherein the maximum width Wg of the groove contour is bigger than a maximum width Ws of the sipe contour, and
• wherein the groove portion has at least one transition section along the longitudinal extension A of the recess, between the ends, wherein the height H having the maximum width Wg of the groove portion changes in this at least one transition section by an amount ΔH, wherein for the ratio ΔH/B of the amount ΔH to the depth B applies ΔH/B≥0.1,
• wherein for the at least one transition section, the longitudinal axis X′ of the groove contour is oriented with respect to the radial axis X of the tyre with an inclination angle α of 0° so as to form a profile path for the radially innermost position of a straight line, where the depth B is essentially constant,
• wherein the extent E is essentially constant,
• wherein for the at least one transition section the sipe portion has a three dimensional configuration wherein the sipe contour comprises at least one segment that is inclined with respect to the radial axis X with inclination angle γ that changes in the range −45°≤γ≤45° so as to form a profile path opening to the tread surface of a zigzag, wavy, sinusoidal or stepped configuration or a combination thereof, and
• wherein the groove portion has straight trace in a longitudinal direction of the groove portion.

A tyre, the tyre comprising:

• a tread having a tread surface for contacting ground and at least one groove-like recess therein forming a free space, the recess having a longitudinal extension A along the surface and a depth B measured in a radial direction with respect to a radial axis of the tyre from the tread surface to a radially innermost position, the recess having a first end and a second end, the ends being opposite to each other along the longitudinal extension A, wherein the free space is divided into a sipe portion opening to the tread surface and
• a groove portion located beneath and radially inwards the sipe portion, wherein in a cross sectional view transverse to the longitudinal extension A of the recess the sipe portion has a sipe contour and the groove portion has a groove contour with a longitudinal axis (X′) and an extent E between an upper end of the groove contour and a lower end of the groove contour, wherein a corresponding width of the groove contour has at least one local maximum width Wg at a height H of the groove contour in the direction of this longitudinal axis, wherein the maximum width Wg of the groove contour is bigger than a maximum width Ws of the sipe contour,
• wherein the groove portion has at least one transition section along the longitudinal extension A of the recess, between the ends, wherein the height H having the maximum width Wg of the groove portion changes in this at least one transition section by an amount ΔH, wherein for the ratio ΔH/B of the amount ΔH to the depth B applies ΔH/≥0.1,
• wherein for the at least one transition section, the longitudinal axis X′ of the groove contour is inclined with respect to the radial axis X of the tyre with an inclination angle α in the range −30°≤α≤30°, and wherein the inclination angle α varies in the range −30°≤α≤30° so as to form a profile path for the radially innermost position of a zigzag, wavy, sinusoidal, or stepped configuration or a combination thereof, where the depth B is essentially constant,
• wherein for the at least one transition section the sipe portion has a three dimensional configuration wherein the sipe contour comprises at least one segment that is inclined with respect to the radial axis X with inclination angle γ that varies in the range −45°≤γ≤45° so as to form a profile path opening to the tread surface of a zigzag, wavy, sinusoidal or stepped configuration or a combination thereof,
• wherein α and γ vary independently from each other, and
• wherein when α is positive, γ is negative and when α is negative, γ is positive.