Patent Description:
The present invention relates to a tire.

<CIT> (Patent Literature <NUM>) has proposed a pneumatic tire having a tread surface provided with grooves. The grooves have groove walls provided with cut-out portions so that the groove walls have zigzag shapes on the tread surface. Tires comprising a plurality of tread blocks, each being provided with at least one notch having a triangular ground contacting surface opening on a block ground contacting surface and a triangular wall surface opening on a block wall surface are disclosed for instance in <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>, respectively.

The cut-out portions in the Patent Literature <NUM> have not been effective enough to compact the snow on a road surface, and there has been room for further improvement in on-snow traction performance.

The present invention was made in view of the above, and a primary object thereof is to provide a tire capable of further improving the on-snow traction performance.

The present invention is a tire as defined in claim <NUM>.

By adopting the above configuration, it is possible that the tire of the present invention further improves the on-snow traction performance.

An embodiment of the present invention will now be described below in conjunction with accompanying drawings.

<FIG> is an enlarged perspective view of a portion of a tread portion <NUM> of a tire <NUM> of the present embodiment. The tire <NUM> of the present embodiment is suitably used as a pneumatic tire for passenger cars suitable for running on snowy roads, especially on roads covered with compacted snow, for example. The present invention may be applied not only to heavy-duty pneumatic tires, but also to non-pneumatic tires not filled with pressurized air.

As shown in <FIG>, the tread portion <NUM> is provided with at least one block <NUM> (a plurality of the blocks <NUM> in the present embodiment) and grooves <NUM> demarcating the block <NUM> (the blocks <NUM> in the present embodiment). The groove <NUM> is a groove-shaped body with a groove width greater than <NUM>, which is clearly distinguished in the present specification from an incised sipe with a width of <NUM> or less.

Each of the blocks <NUM> has a block ground contacting surface <NUM> and block wall surfaces <NUM> extending inwards in a tire radial direction from the block ground contacting surface <NUM> to groove bottoms (<NUM>) of the grooves <NUM>. In each of the blocks <NUM>, each of the block wall surfaces <NUM> is connected with the block ground contacting surface <NUM> via a respective one of block edges <NUM>, for example.

In the case of a pneumatic tire, when the tire <NUM> in a standard state is in contact with a flat surface with zero camber angle by being loaded with a standard tire load, the block ground contacting surface <NUM> is the surface contacting the flat surface The term "standard state" refers to the state in which the tire is mounted on a standard rim, inflated to a standard inner pressure, and loaded with no tire load, in the case of a pneumatic tire for which various standards have been established. In the case of tires for which various standards have not been established or non-pneumatic tires, the standard state means a standard use state according to the purpose of use of the tire and being loaded with no tire load. In the present specification, unless otherwise specified, the dimensions of various parts of the tire <NUM> are the values measured in the standard state.

The term "standard rim" refers to a wheel rim specified for the concerned tire by a standard included in a standardization system on which the tire is based, for example, the "normal wheel rim" in JATMA, "Design Rim" in TRA, and "Measuring Rim" in ETRTO.

The term "standard inner pressure" refers to air pressure specified for the concerned tire by a standard included in a standardization system on which the tire is based, for example, the maximum air pressure in JATMA, maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table in TRA, and "INFLATION PRESSURE" in ETRTO.

The term "standard tire load" refers to a tire load specified for the concerned tire by a standard included in a standardization system on which the tire is based, for example, the "maximum load capacity" in JATMA, maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table in TRA, and "LOAD CAPACITY" in ETRTO. In the case of tires for which various standards have not been established, the term "standard tire load" refers to the maximum applicable load for the use of the tire according to the above-mentioned standards.

The block wall surfaces <NUM> are provided with a plurality of first recesses <NUM>. Each of the first recesses <NUM> is formed so as to extend across the block ground contacting surface <NUM> and a respective one of the block wall surfaces <NUM>. Each of the first recesses <NUM> has a triangular-shaped ground contacting surface opening <NUM> (shown in <FIG>) on the block ground contacting surface <NUM>. Further, each of the first recesses <NUM> also has a triangular-shaped wall surface opening <NUM> (shown in <FIG>) on a respective one of the block wall surfaces <NUM>. The first recesses <NUM> configured as such are capable of capturing and compacting snow within the first recesses <NUM> when running on snow-covered roads. The above-mentioned "triangular-shaped" includes equilateral triangles as well as various other triangles such as isosceles triangles.

<FIG> is a front view of one of the block wall surfaces <NUM>. As shown in <FIG> and <FIG>, each of the wall surface openings <NUM> has a first end <NUM> terminating without reaching a respective one of the groove bottoms (<NUM>). This allows the snow to be compacted more strongly compared to a recess (not shown) with the wall surface opening <NUM> reaching a respective one of the groove bottoms (<NUM>). Therefore, the tire <NUM> can further improve the on-snow traction performance.

<FIG> is a plan view of the tread portion <NUM> in the present embodiment. As shown in <FIG>, the tread portion <NUM> in the present embodiment is formed to have the blocks <NUM> arranged in a tire circumferential direction and a tire axial direction. Further, the grooves <NUM> include a plurality of circumferential grooves 4A extending continuously in the tire circumferential direction and axial grooves 4B extending in the tire axial direction. Each of the circumferential grooves 4A and each of the axial grooves 4B extends linearly in the present embodiment. Each of the circumferential grooves 4A and each of the axial grooves 4B can be formed in a well-known shape.

The blocks <NUM> include crown blocks 3A arranged on a tire equator (C) in a row, shoulder blocks 3B located axially outermost arranged in a pair of rows, and middle blocks 3C arranged in a pair of rows each located between the row of the crown blocks 3A and a respective one of the rows of the shoulder blocks 3B. The block ground contacting surface <NUM> of each of the blocks <NUM> has a rectangular contour shape. It should be noted that the tread pattern of the tread portion <NUM> is not limited to such a manner, and various well-known patterns can be adopted.

The first recesses <NUM> in the present embodiment are provided in the block wall surfaces <NUM> extending to the groove bottoms (<NUM>) of the axial grooves 4B. The first recesses <NUM> are provided on the opposing block wall surfaces <NUM> on both sides of each of the axial grooves 4B, for example. The first recesses <NUM> are provided on the block wall surfaces <NUM> facing the axial grooves 4B demarcating the crown blocks 3A, on the block wall surfaces <NUM> facing the axial grooves 4B demarcating the shoulder blocks 3B, and on the block wall surfaces <NUM> facing the axial grooves 4B demarcating the middle blocks 3C, for example. As a result, driving force and braking force can be used to effectively shear snow blocks, thereby, it is possible that the on-snow traction performance is further improved. It should be noted that the first recesses <NUM> are not limited to such an arrangement. The first recesses <NUM> may be provided on the block wall surfaces <NUM> extending to the groove bottoms (<NUM>) of the circumferential grooves 4A, for example. The first recesses <NUM> configured as such improve the on-snow traction performance during cornering.

<FIG> is a partial plan view of the block ground contacting surface <NUM> of one of the blocks <NUM>. <FIG> is a cross-sectional view taken along A-A line shown in <FIG>, showing a block cross section perpendicular to the block ground contacting surface <NUM>. As shown in <FIG>, each of the ground contacting surface openings <NUM> has a second end <NUM> terminating in the block ground contacting surface <NUM> at a location apart from the block wall surface <NUM>. And each of the first recesses <NUM> has a valley line <NUM> extending from the first end <NUM> to the second end <NUM>. Thus, the valley line <NUM> in the present embodiment extends linearly and radially outward from the first end <NUM>, inclining away from the block wall surface <NUM> in each of the first recesses <NUM>. This allows the valley lines <NUM> to form more firm snow blocks when the block ground contacting surface <NUM> contacts the ground, since the valley lines <NUM> exerts a force in the direction toward the road surface on the snow captured within the first recesses <NUM>. In addition, at the valley lines <NUM> of the first recesses <NUM> provided on the block wall surfaces <NUM> facing the axial grooves 4B, the driving force and the breaking force can be used to push the snow blocks in a direction orthogonal to the axial grooves 4B, therefore, a snow removal effect is exerted.

In a block cross section passing all through the valley line <NUM> and perpendicular to the block ground contacting surface <NUM>, it is preferred that an angle α1 of the valley line <NUM> relative to the block ground contacting surface <NUM> is from <NUM> to <NUM> degrees. Since the angle α1 is <NUM> degrees or more, the volume in each of the first recesses <NUM> can be secured to form a large snow block. Since the angle α1 is <NUM> degrees or less, the snow captured within each of the first recesses <NUM> can be effectively subjected to the force in the direction toward the road surface. In order to effectively achieve this effect, the angle α1 is more preferably <NUM> degrees or more, and more preferably <NUM> degrees or less.

<FIG> is a schematic partial perspective view of one of the blocks <NUM> to illustrate the first recesses <NUM>. As shown in <FIG>, each of the ground contacting surface openings <NUM> has a pair of first edges <NUM> extending in a tapering manner from the block wall surface <NUM> (block edge <NUM>). Further, each of the wall surface openings <NUM> has a pair of second edges <NUM> extending in a tapered manner from the block ground contacting surface <NUM> (block edges <NUM>). The pair of the first edges <NUM> are connected at the second end <NUM>, for example. The pair of the second edges <NUM> are connected at the first end <NUM>, for example.

Each of the first edges <NUM> has a length (La) of <NUM> or more and <NUM> or less. If the length (La) is excessively large, the snow captured within the first recesses <NUM> may not be compressed hard enough. If the length (La) is excessively small, the volume of the snow block formed within each of the first recesses <NUM> is reduced, therefore, the on-snow traction performance may decrease. For this reason, the length (La) is more preferably <NUM> or more and more preferably <NUM> or less. From the same perspective, a length (Lb) of each of the second edges <NUM> is preferably <NUM> or more, more preferably <NUM> or more, and preferably <NUM> or less, more preferably <NUM> or less.

It is preferred that a minimum distance (L1n) between the first recesses <NUM> adjacent to each other is <NUM> or less. This allows more snow blocks to be formed, thereby, it is possible that high on-snow traction performance is exerted. Since the ground contacting surface opening <NUM> and the wall surface opening <NUM> of each of the first recesses <NUM> are triangular in shape, when the first recesses <NUM> are lined up, the minimum distance (L1n) can be smaller compared to, for example, those in which the ground contacting surface openings <NUM> and the wall surface openings <NUM> are square-shaped (not shown). Therefore, the first recesses <NUM> in the present embodiment can exert greater snow shearing force. In the present invention, the minimum distance (L1n) is set to <NUM>.

As shown in <FIG>, <FIG> and <FIG>, the block wall surfaces <NUM> are provided with a plurality of second recesses <NUM> arranged radially inside the first recesses <NUM>. Further, the block wall surfaces <NUM> are provided with a plurality of third recesses <NUM> arranged radially inside the second recesses <NUM>. In each of the blocks <NUM>, each of the second recesses <NUM> is recessed from the block wall surface <NUM> so as to have a triangular-shaped opening 25A formed on the block wall surface <NUM>. Further, in each of the blocks <NUM>, each of the third recesses <NUM> is recessed to have a triangular-shaped opening 25B formed on the block wall surface <NUM>. After the first recesses <NUM> have worn off, the second recesses <NUM> configured as such appear on the block ground contacting surfaces <NUM>, form snow blocks between the road surface, and exert shearing forces. After the second recesses <NUM> have worn off, the third recesses <NUM> appear on the block ground contacting surfaces <NUM>, form snow blocks between the road surface, and exert shearing forces. As just described above, the tire <NUM> of the present embodiment improves the on-snow traction performance over a long period of time. A minimum distance (L1m) in the tire radial direction between one of the first recesses <NUM> and one of the second recesses <NUM> adjacent to each other is preferably <NUM> or less, and more preferably <NUM> or less. In the present invention, the minimum distance (L1m) is set to <NUM>.

Each of the second recesses <NUM> is concave in a cone or pyramid shape so as to form the opening 25A, for example. Each of the second recesses <NUM> is recessed in a triangular pyramid shape so as to have the triangular opening 25A in the present embodiment. Each of the third recesses <NUM> is concave in a cone or pyramid shape so as to form the opening 25B, for example. Each of the third recesses <NUM> is recessed in a triangular pyramid shape so as to have the triangular opening 25B in the present embodiment. This allows for easy snow removal from within each of the recesses <NUM> and <NUM>.

In a front view of the block wall surface <NUM>, the opening 25A of each of the second recesses <NUM> has a contour shape tapering radially inward, for example, an inverted triangle. Further, the opening 25B of each of the third recesses <NUM> has a contour shape tapering radially inward, for example, an inverted triangle. The second recesses <NUM> configured as such are able to form harder snow blocks after the first recesses <NUM> have worn off. Further, the third recesses <NUM> configured as such are able to form more firm snow blocks after the second recesses <NUM> have worn off.

Each of the second recesses <NUM> includes, for example, a second recess end (12t) (shown in <FIG>) that is the most distant from the block wall surface <NUM>, a second inner end (12i) (shown in <FIG>) in the tire radial direction of the opening 25A, and a second valley line (12j) connecting the second recess end (12t) and the second inner end (12i). The second valley line (12j) extends radially outward from the second inner end (12i) to the second recess end (12t) so as to be continuously inclined. This allows the load from the vehicle to effectively act from the second valley line (12j) on the snow taken into each of the second recesses <NUM>, thereby, it is possible that more compacted and harder snow blocks are formed.

Similarly, each of the third recesses <NUM> includes, for example, a third recess end (13t) (shown in <FIG>) that is the most distant from the block wall surface <NUM>, a third inner end (13i) (shown in <FIG>) in the tire radial direction of the opening 25B, and a third valley line (13j) connecting the third recess end (13t) and the third inner end (13i). The third valley line (13j) extends radially outward from the third inner end (13i) to the third recess end (13t) so as to be continuously inclined.

The second valley line (12j) has an angle α2 that is the same as the angle α1 of the valley line <NUM> of each of the first recesses <NUM>, for example. The third valley line (13j) has an angle α3 that is the same as the angle α2 of the second valley line (12j) in the present embodiment. Therefore, the same magnitude of the snow shearing force can be exerted from the first recesses <NUM> through the third recesses <NUM>. The angle α2 is the angle of the second valley line (12j) relative to (a plane parallel to) the block ground contacting surface <NUM> in a block cross section passing all through the second valley line (12j) and perpendicular to the block ground contacting surface <NUM>. The angle α3 is the angle of the third valley line (13j) relative to (a plane parallel to) the block ground contacting surface <NUM> in a block cross section passing all through the third valley line (13j) and perpendicular to the block ground contacting surface <NUM>.

From the same point of view, it is more preferred that each of the second recesses <NUM> has a recess depth D2 that is the same length as a recess depth D1 of each of the first recesses <NUM>. It should be noted that the recess depth D1 is a depth or length in a direction in which each of the first recesses <NUM> is recessed from and orthogonal to the block wall surface <NUM> as shown in <FIG>. The same applies to the recess depths D2 and D3. It is preferred that each of the third recesses <NUM> has a recess depth D3 that is the same length as the recess depth D2 of each of the second recesses <NUM>. The recess depth D1 of each of the first recesses <NUM> is the shortest distance between the block wall surface <NUM> (the wall surface opening <NUM>) and the second end <NUM> thereof. The recess depth D2 of each of the second recesses <NUM> is the shortest distance between the block wall surface <NUM> and the second recess end (12t) thereof. The recess depth D3 of each of the third recesses <NUM> is the shortest distance between the block wall surface <NUM> and the third recess end (13t) thereof.

The second recesses <NUM> are each lined up at a first position (e1) (shown in <FIG>) in the tire radial direction, for example. In the present embodiment, the second recesses <NUM> are arranged so that each of the second inner ends (12i) in the tire radial direction of the openings 25A of the second recesses <NUM> touches (is tangent to) the first position (e1) line. The third recesses <NUM> are lined up at a second position (e2) in the tire radial direction, for example. The third recesses <NUM> are arranged so that each of the third inner ends (13i) in the tire radial direction of the openings 25B of the third recesses <NUM> touches (is tangent to) the second position (e2) line.

As shown in <FIG>, in the front view of the block wall surface <NUM>, the second recesses <NUM> are misaligned with the first recesses <NUM> and the third recesses <NUM> in a longitudinal direction of the block wall surface <NUM> (orthogonal to the tire radial direction). This reduces rigidity difference of each of the blocks <NUM>. Further, in the front view of the block wall surface <NUM>, the first recesses <NUM> and the third recesses <NUM> are arranged at the same positions so as to be aligned with each other in the longitudinal direction of the block wall surface <NUM>. The second recesses <NUM> are displaced by half a pitch in the longitudinal direction of the block wall surface <NUM> from the first recesses <NUM> and the third recesses <NUM> in the present embodiment.

Each of the blocks <NUM> includes, on the block wall surface <NUM>, block convexities <NUM> each surrounded by the adjacent first recesses <NUM> and one of the second recesses <NUM> located radially inside these first recesses <NUM>. Each of the block convexities <NUM> in the present embodiment has a triangular surface with a corner pointing toward the block ground contacting surface <NUM>, which has a high piercing effect on the roads covered with compacted snow, thereby, the on-snow traction performance can be further improved. When the first recesses <NUM> wear off, the block convexities each surrounded by the adjacent second recesses <NUM> and one of the third recesses <NUM> located radially inside these second recesses <NUM> appear on the block ground contacting surface <NUM>. Further, when the second recesses <NUM> wear off, the block convexities <NUM> each surrounded by the adjacent third recesses <NUM> and one of later-described fourth recesses <NUM> located radially inside these third recesses <NUM> appear on the block ground contacting surface <NUM>.

In the front view of each of the block wall surfaces <NUM> in the present embodiment, an opening area S1 of the wall surface opening <NUM> of each of the first recesses <NUM> is the same as an opening area S2 of the opening 25A of each of the second recesses <NUM>. It should be noted that the opening area S1 is surrounded (demarcated) by the second edges <NUM> and an extension of the block ground contacting surface <NUM> (i.e., an extension of the block edge <NUM>). Further, the opening area S2 of the opening 25A of each of the second recesses <NUM> is the same as an opening area S3 of the opening 25B of each of the third recesses <NUM>. As just described, the opening areas S1 to S3 of the recesses <NUM> to <NUM> are the same in the present embodiment. In other words, the first recesses <NUM>, the second recesses <NUM>, and the third recesses <NUM> have the same shape. It should be noted that the shape of each of the first recesses <NUM> is regarded as if the ground contacting surface opening <NUM> is filled by virtual extension of the block ground contacting surface <NUM>. In the blocks <NUM> configured as such, each of the recesses <NUM> to <NUM> exerts the same snow compaction effect, which helps to improve the on-snow traction performance. In the present specification, the above-mentioned "same" includes differences in opening area due to precision errors in tire manufacturing.

Each of the block wall surfaces <NUM> in the present embodiment is provided with a plurality of the fourth recesses <NUM> formed radially inside the third recesses <NUM>. The fourth recesses <NUM> are arranged at a third position (e3) (shown in <FIG>) in the tire radial direction, for example. The fourth recesses <NUM> are formed in the same shape as the second recesses <NUM> in the present embodiment. When the third recesses <NUM> wear off, the fourth recesses <NUM> configured as such appear on the block ground contacting surface <NUM> and form snow blocks between the road surface to exert the snow shearing forces. It should be noted that the block wall surfaces <NUM> may, for example, have a plurality of fifth recesses (not shown) arranged radially inside the fourth recesses <NUM>, and may have a plurality of sixth recesses (not shown) arranged radially inside the fifth recesses. It is preferred that the fourth recesses <NUM>, the fifth recesses, and the sixth recesses are formed in the same shape as the second recesses <NUM> or the third recesses <NUM>, for example.

<FIG> is a front view of one of the block wall surfaces <NUM> according to another embodiment. The same components as those in the previously described embodiment are denoted by the same reference numerals and the description thereof may be omitted. As shown in <FIG>, in the present embodiment, the blocks <NUM> include outer blocks (3r) and inner blocks (3q) arranged adjacent to and axially inside the outer blocks (3r). It should be noted that the outer blocks (3r) are arranged in a circumferential row and the inner blocks (3q) are arranged in a circumferential row and that only one of the outer blocks (3r) and one of the inner blocks (3q) are shown in <FIG>.

The outer blocks (3r) are provided with first recesses (11r) (outer first recesses) each having a volume larger than a volume of each of first recesses (11q) (inner first recesses) provided in the inner blocks (3q), for example. The outer blocks (3r) are provided with second recesses (12r) each having a volume larger than a volume of each of second recesses (12q) provided in the inner blocks (3q), for example. The outer blocks (3r) are provided with third recesses (13r) each having a volume larger than a volume of each of third recesses (13q) provided in the inner blocks (3q), for example. As a result, the outer blocks (3r) deform more than the inner blocks (3q) during cornering when a large lateral force acts on them, therefore, the snow shearing force can be increased in the first recesses (11r), the second recesses (12r), and the third recesses (13r). Thereby, the on-snow traction performance during cornering is improved. It should be noted that the first recesses (11r) (and also the second recesses (12r) and the third recesses (13r)) may be arranged in an axially outer part and the first recesses (11q) (and also the second recesses (12q) and the third recesses (13q)) may be arranged in an axially inner part of a single block <NUM>.

In the outer blocks (3r), the wall surface opening <NUM> of each of the first recesses (11r) has an opening area same as an opening area of the opening 25A of each of the second recesses (12r) and an opening area of the opening 25B of each of the third recesses (13r), for example. Further, in the inner blocks (3q), the wall surface opening <NUM> of each of the first recesses (11q) has an opening area same as an opening area of the opening 25A of each of the second recesses (12q) and an opening area of the opening 25B of each of the third recesses (13q), for example.

<FIG> is a front view of one of the block wall surfaces <NUM> according to yet another embodiment. <FIG> is a cross-sectional view taken along B-B line shown in <FIG>. The same components as those in the previously described embodiments are denoted by the same reference numerals and the description thereof may be omitted. As shown in <FIG>, each of the block wall surfaces <NUM> in this embodiment is provided with a plurality of the first recesses <NUM>, the second recesses <NUM>, and the third recesses <NUM>.

Generally, a tire is manufactured by vulcanizing a green tire put into a vulcanization mold (not shown). The vulcanization mold for manufacturing the tire <NUM> of the present invention is provided with convex portions that form the inverted pattern of the first recesses <NUM> through the third recesses <NUM>, and thus the first recesses <NUM> through the third recesses <NUM> are formed when the green tire is vulcanized. Therefore, when vulcanization is finished, the convex portions of the vulcanization mold are engaged with the second recesses <NUM> and the third recesses <NUM> of the tire <NUM>. Each of the second recesses <NUM> in the present embodiment has a length L2 in the tire radial direction smaller than a length L1 in the tire radial direction of each of the first recesses <NUM>. Further, each of the third recesses <NUM> has a length L3 in the tire radial direction smaller than the length L2 of each of the second recesses <NUM>. As a result, the engagement of the second recesses <NUM> and the third recesses <NUM> with the convex portions of the vulcanization mold is small, which makes it easier to remove the tire <NUM> from the vulcanization mold.

Further in general, when running on roads covered with compacted snow, snow taken in the grooves <NUM> rarely reaches the groove bottoms (<NUM>) at the early stage of wear, and is less likely to be hardened by the grooves <NUM>. Furthermore, at the late stage of wear, the depths of the grooves <NUM> become smaller, therefore, snow taken in the grooves <NUM> reaches the groove bottoms (<NUM>), and is likely to be strongly compacted by the groove bottoms (<NUM>). In this embodiment, the snow shearing force is maintained high in the early stage of wear since the first recesses <NUM> having the large length L1 are able to compact the snow. Further, at the late stage of wear, the first recesses <NUM> disappear and only the second recesses <NUM> and/or the third recesses <NUM> appear on the block ground contacting surfaces <NUM> and the block wall surfaces <NUM>. The length L2 of each of the second recesses <NUM> and the length L3 of each of the third recesses <NUM> are smaller than the length L1 of each of the first recesses <NUM>, but the grooves <NUM> themselves and the second recesses <NUM> and/or the third recesses <NUM> form hard snow blocks, the snow shearing force is maintained high even at the late stage of wear. In order to effectively exert such an action, it is preferred that the third recesses <NUM> are provided so as to appear on the block ground contacting surfaces <NUM> when the grooves are <NUM>% worn.

Although not particularly limited, the length L1 of each of the first recesses <NUM> is preferably <NUM> or more, further preferably <NUM> or more, and preferably <NUM> or less, further preferably <NUM> or less. The length L2 of each of the second recesses <NUM> is preferably <NUM> or more, further preferably <NUM> or more, and preferably <NUM> or less, further preferably <NUM> or less. The length L3 of each of the third recesses <NUM> is preferably <NUM> or more, further preferably <NUM> or more, and preferably <NUM> or less, further preferably <NUM> or less.

From a similar point of view, the recess depth D2 of each of the second recesses <NUM> is smaller than the recess depth D1 of each of the first recesses <NUM>, for example. Further, the recess depth D3 of each of the third recesses <NUM> is smaller than the recess depth D2 of each of the second recesses <NUM>, for example. It should be noted that each of the first recesses <NUM> in this embodiment has a width W1 which is the same as a width W2 of each of the second recesses <NUM> and a width W3 of each of the third recesses <NUM>. The widths W1, W2, and W3 are the widths in a direction along the block edge <NUM> and in a longitudinal direction of one of the grooves <NUM> the first recesses <NUM>, the second recesses <NUM>, and the third recesses <NUM> face.

Claim 1:
A tire (<NUM>) comprising:
a tread portion (<NUM>) provided with one or more blocks (<NUM>) each demarcated by grooves (<NUM>), wherein
the or each block (<NUM>) has a block ground contacting surface (<NUM>) and a block wall surface (<NUM>) facing one of the grooves (<NUM>) and extending inwards in a tire radial direction from the block ground contacting surface (<NUM>) to a groove bottom (<NUM>) of the one of the grooves (<NUM>),
the block wall surface (<NUM>) is provided with a plurality of first recesses (<NUM>),
each of the first recesses (<NUM>) is formed so as to extend across the block ground contacting surface (<NUM>) and the block wall surface (<NUM>),
each of the first recesses (<NUM>) has a triangular ground contacting surface opening (<NUM>) on the block ground contacting surface (<NUM>) and a triangular wall surface opening (<NUM>) on the block wall surface (<NUM>), wherein each of the ground contacting surface openings (<NUM>) has a pair of first edges (<NUM>) extending in a tapering manner from the block wall surface (<NUM>), whereby the pair of the first edges (<NUM>) are connected at a second end (<NUM>), and
the wall surface opening (<NUM>) has a first end (<NUM>) terminating without reaching the groove bottom (<NUM>), wherein each of the wall surface openings (<NUM>) has a pair of second edges (<NUM>) extending in a tapered manner from the block ground contacting surface (<NUM>), whereby the pair of the second edges (<NUM>) are connected at the first end (<NUM>), characterized in that
the block wall surface (<NUM>) is provided with a plurality of second recesses (<NUM>) arranged radially inside the first recesses (<NUM>), and
each of the second recesses (<NUM>) is recessed to have a triangular opening (25A) on the block wall surface (<NUM>).