Patent ID: 8919399
Filing Date: 2014-12-30
Classification: B60C,Y10S

Abstract:
1. A tread band for a tire, this tread band being provided with a plurality of grooves delimiting elements in relief, these grooves having a depth H, this tread band having a tread surface designed to come into contact with the road surface during running, the tread surface comprising, on a plurality of its elements in relief, a plurality of recesses of total depth H*, each recess comprising at least two cavities of a first type of cavities, each of these cavities of a first type being delimited by a main wall and having a depth Hi, the main wall of each cavity of the first type is such that its intersection with a virtual surface parallel to the running surface in the new condition and passing through the points of the said wall that are furthest towards the outside of the tread forms an exterior contour that is closed and of length Ce, the main wall of each cavity of the first type is such that its intersection with a virtual surface parallel to the running surface in the new condition and passing through the points of the main wall furthest towards the inside of the tread forms an interior contour which is closed and of length of length Ci, wherein the cavities of a first type are arranged in such a way as to succeed one another in a direction oriented from the tread surface towards the inside of the tread strip, that is to say so that the external contour of a cavity of a first type of recess is located, in the direction of the thickness of the tread, at a distance from the tread surface in the new condition which is greater than or equal to the distance separating the internal contour of the preceding cavity from the same tread surface, and in that the length Ce of the exterior contour of a cavity is greater than the length Ci of the interior contour of the same cavity, this tread band further having a cavity of a second type inserted between two cavities of a first type, wherein such cavity of the second type being delimited by a wall of which the intersection with a surface parallel to the tread surface in the new condition and passing through the outermost points of the said wall forms a closed contour of length equal to the length Ci of the interior contour of the cavity of the first type to which this cavity of the second type is connected, this cavity of the second type being connected to a first-type cavity of rank i+1 by a contour of a length equal to the length Ce of the exterior contour of the said cavity of rank i+1, and wherein the depths of the cavities of the second type are less than the depths of the cavities of the first type wherein the length Ci of the closed interior contour of at least the cavity furthest towards the inside of the tread (that is to say the cavity of rank N) is equal to zero or substantially close to zero.