JP5400593B2 - tire - Google Patents

Description

  The present invention relates to a tire including a rib-like land portion extending in the tire circumferential direction, and having a circumferential groove adjacent to the land portion and extending in the tire circumferential direction.

  Conventionally, in a tire mounted on a passenger car or the like, a tread pattern in which a lateral groove extending in the tread width direction is formed in a rib-like land portion extending in the tire circumferential direction has been widely adopted in order to improve braking performance. For example, a tire is known in which a large number of auxiliary lateral grooves that extend in the tread width direction and divide the land portion are formed in a rib-shaped land portion (for example, Patent Document 1).

  According to such a tire, a so-called edge component is increased by a large number of auxiliary lateral grooves, so that the braking performance is improved.

JP 2004-66922 A (page 4, FIG. 1)

  However, tires employing the tread pattern as described above have the following problems. That is, the rib-like land portion is divided into a plurality of blocks by the auxiliary lateral grooves, but at the initial stage of tire wear, the block height is high and the auxiliary lateral grooves are deep. For this reason, there is a problem that the block rigidity (shear rigidity) of the land portion is low and the end portion on the auxiliary lateral groove side of the block is deformed so that the braking performance is lowered during braking of the tire-equipped vehicle.

  Accordingly, an object of the present invention is to provide a tire that can exhibit more stable braking performance from the initial stage of wear to after a certain amount of wear.

  In order to solve the above-described problems, the present invention has the following features. First, a first feature of the present invention includes a rib-like land portion (land portion 20) extending in the tire circumferential direction (tire circumferential direction TC), and adjacent to the land portion, and a circumferential groove extending in the tire circumferential direction. A tire (for example, a pneumatic tire 1) in which (circumferential groove 30) is formed, and the tread surface (tread surface 10) of the land portion is in a state where a normal load is applied to the tire and is in contact with the road surface. In this state, a smooth surface having no air gap is formed, and the circumferential groove is formed in the first groove portion (shallow groove portion 40) formed between the land portions adjacent to each other and the first groove portion in the tire circumferential direction. And a second groove portion (deep groove portion 50) formed between the adjacent land portions, the second groove portion having a groove bottom (groove bottom 40c) of the first groove portion as an upper end, Recessed inside the tire radial direction (tire radial direction TR) from the first groove The gist that you are.

  According to such a feature, the tread surface of the land portion forms a smooth surface with no gap in a state where a normal load is applied to the tire and in a state where the tire is in contact with the road surface. According to this, the tread surface of the land portion can ensure the block rigidity (shear rigidity) of the land portion as compared with the case where the air gap is formed in a state of being in contact with the road surface. For this reason, at the initial stage of tire wear, deformation of the land portion during braking of the tire-equipped vehicle can be suppressed, and braking performance can be improved.

  Further, the second groove portion is recessed inward in the tire radial direction from the first groove portion with the groove bottom of the first groove portion as an upper end. According to this, after a certain amount of wear from the beginning of wear, the height of the land portion becomes low, and the block rigidity of the land portion can be secured. For this reason, with the deformation of the land portion due to the low block rigidity of the land portion being suppressed, the edge component is increased by the first groove portion and the second groove portion, and the braking performance can be improved.

  In this way, the tread surface of the land portion forms a smooth surface, and the second groove portion is recessed inward in the tire radial direction from the first groove portion, so that more stable braking performance from the initial wear to after a certain amount of wear. Can be demonstrated.

  A second feature of the present invention relates to the first feature of the present invention, and at least a side wall (side wall 40a) of the first groove portion of the first groove portion and the second groove portion has a tread width direction (tread). In a cross-sectional view along the width direction TW) and the tire radial direction, a distance (distance CP) from a straight line (straight line PL) parallel to the tire equator line through the circumferential groove side end of the land portion is the first distance. The gist is that the groove portion is inclined so as to become longer toward the deepest portion (the deepest portion 40b).

  A third feature of the present invention relates to the second feature of the present invention, and is summarized in that the shape of the side wall of the first groove is a half-moon shape recessed inward in the tire radial direction in the cross-sectional view.

  A fourth feature of the present invention relates to the first to third features of the present invention, and is summarized in that the tread surface of the land portion extends in the tire circumferential direction without forming a groove and a concave portion.

  According to the characteristics of the present invention, it is possible to provide a tire that can exhibit more stable braking performance from the initial stage of wear to after a certain amount of wear.

FIG. 1 is a development view showing a part of the tread surface 10 of the pneumatic tire 1 according to the present embodiment. FIG. 2 is a perspective view showing a part of the tread surface 10 of the pneumatic tire 1 according to the present embodiment. Fig.3 (a) is a tread width direction sectional drawing (AA sectional drawing of FIG. 1) which shows a part of tread surface 10 of the pneumatic tire 1 which concerns on this embodiment. FIG. 3B is an enlarged schematic view showing only the circumferential groove 31 in FIG. FIG. 4 is an enlarged schematic view showing the shallow groove portion 40 and the deep groove portion 50. FIG. 5 is a development view illustrating a part of the tread surface 10A of the pneumatic tire 1A according to the first modification. FIG. 6 is a perspective view showing a part of the tread surface 10A of the pneumatic tire 1A according to the first modification. FIG. 7 is a development view illustrating a part of the tread surface 10B of the pneumatic tire 1B according to the second modification. FIG. 8 is a perspective view illustrating a part of the tread surface 10B of the pneumatic tire 1B according to the second modification. FIG. 9 is a development view illustrating a part of the tread surface 10C of the pneumatic tire 1C according to the third modification. FIG. 10 is a perspective view illustrating a part of the tread surface 10C of the pneumatic tire 1C according to the third modification.

  Next, an embodiment of a pneumatic tire according to the present invention will be described with reference to the drawings. Specifically, (1) Overall configuration of pneumatic tire, (2) Detailed configuration of circumferential groove, (3) Modified example, (4) Comparative evaluation, (5) Action / effect, (6) Other implementations A form is demonstrated.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Whole structure of pneumatic tire First, the whole structure of the pneumatic tire 1 which concerns on this embodiment is demonstrated, referring drawings. FIG. 1 is a development view showing a part of the tread surface 10 of the pneumatic tire 1 according to the present embodiment. The pneumatic tire 1 may be filled with an inert gas such as nitrogen gas instead of air.

  As shown in FIG. 1, the pneumatic tire 1 includes a rib-like land portion 20 extending in the tire circumferential direction TC. The tread surface 10 of the land portion 20 is formed with a circumferential groove 30 that is adjacent to the land portion 20 and extends in the tire circumferential direction TC.

  The tread tread surface 10 of the land portion 20 forms a smooth surface with no gap in a state where a normal load is applied to the pneumatic tire 1 and in a state where the pneumatic tire 1 is in contact with the road surface. In the present embodiment, the tread surface 10 of the land portion 20 extends in the tire circumferential direction without forming grooves and recesses.

  The land portion 20 includes a land portion 21, a land portion 22, a land portion 23, and a land portion 24 from the left side to the right side of FIG. On the other hand, the circumferential groove 30 includes a circumferential groove 31, a circumferential groove 32, and a circumferential groove 33 from the left side to the right side in FIG.

  The circumferential groove 31 and the circumferential groove 33 of the circumferential groove 30 include a shallow groove portion 40 (first groove portion) and a deep groove portion 50 (second groove portion).

(2) Detailed Configuration of Circumferential Groove Next, detailed configurations of the circumferential groove 31 and the circumferential groove 33 described above will be described with reference to the drawings. FIG. 2 is a perspective view showing a part of the tread surface 10 of the pneumatic tire 1 according to the present embodiment. Fig.3 (a) is a tread width direction sectional drawing (AA sectional drawing of FIG. 1) which shows a part of tread surface 10 of the pneumatic tire 1 which concerns on this embodiment. FIG. 3B is an enlarged schematic view showing only the circumferential groove 31 in FIG. FIG. 4 is an enlarged schematic view showing the shallow groove portion 40 and the deep groove portion 50. The tread width direction sectional view shows a sectional view along the tread width direction TW and the tire radial direction TR.

  In the following, since the configuration of the circumferential groove 31 and the configuration of the circumferential groove 33 are the same, the configuration of the circumferential groove 31 will be mainly described. 3 and 4, only the circumferential groove 31 is shown.

  As shown in FIGS. 1 to 4, the shallow groove portion 40 is formed between the land portion 21 and the land portion 22 adjacent to each other. The shape of the side wall 40a of the shallow groove portion 40 is a half-moon shape recessed in the tire radial direction TR in the cross section in the tread width direction (see FIGS. 2 and 3).

  As shown in FIG. 3 (b), at least the side wall 40a of the shallow groove portion 40 out of the shallow groove portion 40 and the deep groove portion 50 passes through the circumferential groove 30 side end of the land portion 20 in the cross section in the tread width direction. The distance CP between the equator line CL and the straight line PL parallel to the equatorial line CL is inclined so as to become longer toward the deepest portion 40b of the shallow groove portion 40. The shallow groove portion 40 includes an inner shallow groove 41 and an outer shallow groove 42 (see FIGS. 1 to 3).

  The inner shallow groove 41 is positioned closer to the tire equator line CL than the in-groove center line DCL passing through the tread width direction TW of the circumferential groove 31 and the circumferential groove 33. The outer shallow groove 42 is continuous with the inner shallow groove 41 and is located outside the in-groove center line DCL in the tread width direction TW.

  The inner shallow groove 41 and the outer shallow groove 42 are curved so as to be opposite to the tire circumferential direction TC. Specifically, as shown in FIG. 4, the outer convex portion 41a that protrudes when the inner shallow groove 41 is curved and the outer convex portion 42a that protrudes when the outer shallow groove 42 is curved are the center in the groove, respectively. Located on the line DCL side. That is, the inner shallow groove 41 and the outer shallow groove 42 are provided point-symmetrically with respect to the center point P1 of the shallow groove portion 40 located on the in-groove center line DCL. Further, the end portion 41p on the land portion 22 side in the inner shallow groove 41 and the end portion 42p of the land portion 21 in the outer shallow groove 42 are arranged so as to be shifted in the tire circumferential direction TC.

  The deep groove portion 50 is adjacent to the shallow groove portion 40 in the tire circumferential direction TC and extends in the tread width direction TW. Specifically, the deep groove portion 50 extends so as to be curved along the tread width direction TW in the tread tread view. The deep groove portion 50 has a groove bottom 40c of the shallow groove portion 40 as an upper end and is recessed more inward in the tire radial direction TR than the shallow groove portion 40.

  The deep groove portion 50 is more rectangular than the shallow groove portion 40 in the cross section in the tread width direction. Specifically, the shape of the side wall 50a of the deep groove portion 50 is a straight shape along the tire radial direction TR in the cross section in the tread width direction. The shape of the groove bottom 50b of the deep groove portion 50 is a straight line shape along the tread width direction TW in the cross section in the tread width direction. The boundary between the side wall 50a and the groove bottom 50b is continuous in a curved shape in the cross section in the tread width direction. The deep groove part 50 is comprised by the inner side deep groove 51 and the outer side deep groove 52 (refer FIGS. 1-4).

  The inner deep groove 51 is located closer to the tire equator line CL than the in-groove center line DCL. The outer deep groove 52 is continuous with the inner deep groove 51 and is located outside the in-groove center line DCL in the tread width direction TW.

  The inner deep groove 51 and the outer deep groove 52 are curved so as to be opposite to the tire circumferential direction TC. Specifically, as shown in FIG. 4, the outer convex portion 51 a that protrudes when the inner deep groove 51 curves and the outer convex portion 52 a that protrudes when the outer deep groove 52 curves are each in-groove center line DCL. Located on the side. That is, the inner deep groove 51 and the outer deep groove 52 are provided point-symmetrically with respect to the center point P2 of the deep groove portion 50 located on the in-groove center line DCL. Further, the end portion 51p on the land portion 22 side in the inner deep groove 51 and the end portion 52p of the land portion 21 in the outer deep groove 52 are arranged so as to be shifted in the tire circumferential direction TC.

(3) Modification Example Next, a modification example of the tread surface 10 of the pneumatic tire 1 according to the embodiment described above will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same part as the tread surface 10 of the pneumatic tire 1 which concerns on embodiment mentioned above, and a different part is mainly demonstrated.

(3-1) Modification 1
First, the configuration of the tread surface 10A of the pneumatic tire 1A according to Modification 1 will be described with reference to the drawings. FIG. 5 is a development view illustrating a part of the tread surface 10A of the pneumatic tire 1A according to the first modification. FIG. 6 is a perspective view showing a part of the tread surface 10A of the pneumatic tire 1A according to the first modification.

  In the embodiment described above, the land portion 20 is not formed with a groove and a recess. On the other hand, in the first modification, as shown in FIGS. 5 and 6, the land portion 20 is provided with a plurality of auxiliary lateral grooves 60.

  Specifically, a plurality of auxiliary lateral grooves 61 and a plurality of auxiliary lateral grooves 64 are formed in the land portion 21 and the land portion 24 at predetermined intervals in the tire circumferential direction TC. Each of the auxiliary lateral grooves 61 and the auxiliary lateral grooves 64 extends so as to be curved along the tread width direction TW when viewed from the tread surface, and opens in the circumferential groove 31 or the circumferential groove 33. Each of the auxiliary horizontal groove 61 and the auxiliary horizontal groove 64 has a width that is smaller than the width of each of the circumferential groove 31, the circumferential groove 32, and the circumferential groove 33 along the tread width direction TW.

  A plurality of auxiliary lateral grooves 62 and a plurality of auxiliary lateral grooves 63 are formed in the land portion 22 and the land portion 23 at predetermined intervals in the tire circumferential direction TC. Each of the auxiliary horizontal groove 62 and the auxiliary horizontal groove 63 is provided on an extension line along the auxiliary horizontal groove 61 or an extension line along the auxiliary horizontal groove 64. One end of the auxiliary lateral groove 62 and the auxiliary lateral groove 63 located outside the tread width direction TW opens in the circumferential groove 31 or the circumferential groove 33. On the other hand, the other end of the auxiliary lateral groove 62 and the auxiliary lateral groove 63 located on the tire equator line CL side terminates in the land portion 22 or the land portion 23. Each of the auxiliary horizontal grooves 62 and the auxiliary horizontal grooves 63 has a width equivalent to the widths of the auxiliary horizontal grooves 61 and the auxiliary horizontal grooves 64.

  The tread tread surface 10A of the land portion 20 forms a smooth surface with no air gap in a state where a normal load is applied to the pneumatic tire 1 and in a state where the pneumatic tire 1 is in contact with the road surface. That is, the land portion 20 partitioned by the auxiliary lateral groove 60 described above is smoothed by contact between adjacent ones in the tire circumferential direction TC so that the auxiliary lateral groove 60 (gap) is closed in a state where the land portion 20 is in contact with the road surface. Form a surface.

(3-2) Modification 2
Next, the configuration of the tread surface 10B of the pneumatic tire 1B according to Modification 2 will be described with reference to the drawings. FIG. 7 is a development view illustrating a part of the tread surface 10B of the pneumatic tire 1B according to the second modification. FIG. 8 is a perspective view illustrating a part of the tread surface 10B of the pneumatic tire 1B according to the second modification.

  In the embodiment described above, the shallow groove portion 40 and the deep groove portion 50 are provided in two circumferential grooves (the circumferential groove 31 and the circumferential groove 33). On the other hand, in the modified example 2, as shown in FIGS. 7 and 8, the shallow groove portion 40 and the deep groove portion 50 are provided in one circumferential groove.

  Specifically, the shallow groove portion 40 and the deep groove portion 50 are provided only in the circumferential groove 31 located on the leftmost side with respect to the tire equator line CL. In the second modification, the circumferential groove 30 is constituted by four circumferential grooves. That is, the circumferential groove 30 includes a circumferential groove 31, a circumferential groove 32, a circumferential groove 33, and a circumferential groove 34.

  The number of the circumferential grooves 30 and the configuration (shape, number, etc.) of the auxiliary lateral grooves 60 are not limited to those described in the embodiment, and can be appropriately selected according to the purpose.

  Further, the shallow groove portion 40 and the deep groove portion 50 are not necessarily provided only in the circumferential groove 31 positioned on the leftmost side with respect to the tire equator line CL. For example, the circumferential groove 32 positioned in the vicinity of the tire equator line CL. Or may be provided only in the circumferential groove 33, or may be provided only in the circumferential groove 34 located on the rightmost side with respect to the tire equator line CL.

(3-3) Modification 3
Next, the configuration of the tread surface 10C of the pneumatic tire 1C according to Modification 3 will be described with reference to the drawings. FIG. 9 is a development view illustrating a part of the tread surface 10C of the pneumatic tire 1C according to the third modification. FIG. 10 is a perspective view illustrating a part of the tread surface 10C of the pneumatic tire 1C according to the third modification.

  In the embodiment described above, the end portion 41p on the land portion 22 side in the inner shallow groove 41 and the end portion 42p of the land portion 21 in the outer shallow groove 42 are arranged so as to be shifted in the tire circumferential direction TC. In the embodiment, the end portion 51p on the land portion 22 side in the inner deep groove 51 and the end portion 52p of the land portion 21 in the outer deep groove 52 are arranged so as to be shifted in the tire circumferential direction TC.

  On the other hand, in the modified example 3, as shown in FIGS. 9 and 10, the end portion 41p on the land portion 22 side in the inner shallow groove 41 and the end portion 42p of the land portion 21 in the outer shallow groove 42 are: They are arranged at the same position with respect to the tire circumferential direction TC. That is, the inner shallow groove 41 and the outer shallow groove 42 are provided symmetrically with respect to the tire equator line CL (in-groove center line DCL).

  Similarly, the end portion 51p on the land portion 22 side in the inner deep groove 51 and the end portion 52p of the land portion 21 in the outer deep groove 52 are disposed at the same position with respect to the tire circumferential direction TC. The inner deep groove 51 and the outer deep groove 52 are provided symmetrically with respect to the tire equator line CL (in-groove center line DCL).

  9 and 10, the circumferential groove 30 is constituted by three circumferential grooves (a circumferential groove 31, a circumferential groove 32, and a circumferential groove 33). And the shallow groove part 40 and the deep groove part 50 are provided only in the circumferential groove | channel 32 located on the tire equator line CL.

  Note that the number of circumferential grooves 30 and the configuration (shape, number, etc.) of auxiliary lateral grooves are not limited to those described in the embodiment, and can be appropriately selected according to the purpose.

  Further, the shallow groove portion 40 and the deep groove portion 50 do not need to be provided only in the circumferential groove 32 positioned on the tire equator line CL, for example, only the circumferential groove 31 positioned on the leftmost side with respect to the tire equator line CL. Or may be provided only in the circumferential groove 33 located on the rightmost side with respect to the tire equator line CL.

(4) Comparative Evaluation Next, in order to further clarify the effect of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (4-1) Configuration of each pneumatic tire and (4-2) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(4-1) Configuration of Each Pneumatic Tire First, a pneumatic tire according to a comparative example and an example will be briefly described. In addition, the data regarding a pneumatic tire were measured on the conditions shown below.

・ Tire size: 225 / 45R17
・ Rim size: 7J-17
・ Vehicle conditions: Domestic FF car (displacement 2000cc)
・ Internal pressure condition: Regular internal pressure ・ Load condition: Driver load + 600N
In the pneumatic tire according to the comparative example, the shallow groove portion 40 and the deep groove portion 50 described in the embodiment are not formed in the circumferential groove. Each land portion is formed with an auxiliary lateral groove communicating with each circumferential groove. The auxiliary lateral groove has a width larger than the width of the auxiliary lateral groove 60 described in the embodiment.

  On the other hand, in the pneumatic tire according to the example, the shallow groove portion 40 and the deep groove portion 50 are formed in the circumferential groove 30. That is, the groove | channel and the recessed part are not formed in the tread surface 10 of the pneumatic tire which concerns on an Example.

  In addition, the pneumatic tire which concerns on a comparative example and an example shall be a tread pattern shown in embodiment (FIG.7 and FIG.8) mentioned above. In the pneumatic tire according to the comparative example and the example, the configuration is the same except for the configuration of the circumferential groove and the configuration of the auxiliary lateral groove.

(4-2) Evaluation Results Next, the evaluation results of the braking performance of the vehicle equipped with each tire (new and worn) will be described with reference to Table 1.

(4-2-1) Braking performance when tires are new The braking performance when tires are new is that a vehicle equipped with a pneumatic tire according to a comparative example lacks full brake at a speed of 60 km / h on a test course with a water depth of 2 mm. The distance until the vehicle stopped (deceleration) was set to '100', and the deceleration of the vehicle equipped with the pneumatic tire of the example was evaluated by a professional driver. The larger the index, the better the braking performance.

  As a result, as shown in Table 1, the vehicle equipped with the pneumatic tire according to the example has better braking performance when the tire is new than the vehicle equipped with the pneumatic tire according to the comparative example. I understood.

(4-2-2) Braking performance during tire wear As for the braking performance during tire wear (at 50% wear), the pneumatic tire according to the comparative example was mounted in the same manner as the braking performance test when the tire was new. The deceleration of the vehicle was set to '100', and the deceleration of the vehicle equipped with the pneumatic tire of the example was evaluated by a professional driver. The larger the index, the better the braking performance.

  As a result, as shown in Table 1, the vehicle equipped with the pneumatic tire according to the example is superior in braking performance at the time of tire wear compared to the vehicle equipped with the pneumatic tire according to the comparative example. I understood.

(5) Actions / Effects In the embodiment described above, the tread tread 10 forms a smooth surface without a gap in a state where a normal load is applied to the pneumatic tire 1 and in a state where the pneumatic tire 1 is in contact with the road surface. That is, the tread tread surface 10 forms a smooth surface, the tread tread surface 10 does not have grooves and recesses (for example, auxiliary lateral grooves 60) (FIGS. 1 and 2), and the tread tread surface 10 has grooves and recesses. Even in the case where (for example, the auxiliary lateral groove 60) is formed, the closed state (FIGS. 5 and 6) is included in the state where the tread surface 10 is in contact with the road surface. According to this, the block rigidity (shear rigidity) of the land portion 20 can be ensured as compared with the case where the gap is formed in the state where the tread tread 10 is in contact with the road surface. For this reason, in the initial stage of wear of the pneumatic tire 1, deformation of the land portion 20 during braking of the tire-equipped vehicle can be suppressed, and braking performance can be improved.

  Further, the deep groove portion 50 has a groove bottom 40c of the shallow groove portion 40 as an upper end, and is recessed more inward in the tire radial direction TR than the shallow groove portion 40. According to this, the block rigidity of the land portion 20 increases as the height of the land portion 20 decreases after a certain amount of wear from the beginning of wear. For this reason, the deformation of the land portion 20 is suppressed, the edge component is increased by the shallow groove portion 40 and the deep groove portion 50, and the braking performance can be improved.

  As described above, the tread tread 10 forms a smooth surface, and the deep groove portion 50 is recessed in the tire radial direction TR from the shallow groove portion 40, so that more stable braking performance from the beginning of wear to after a certain amount of wear. Can be demonstrated.

  By the way, when a gap is formed when the tread tread surface 10 is in contact with the road surface as in the prior art, the flow of rain and the like in the circumferential groove becomes turbulent flow due to the auxiliary lateral groove on the wet road surface, and drainage (hydroplaning performance) ) Will decrease. However, in the embodiment, since the tread tread surface 10 forms a smooth surface, the flow of water in the circumferential groove 30 (the circumferential groove 31 and the circumferential groove 33) is less likely to be turbulent and stable. Can be improved.

  Moreover, in the conventional land part in which the auxiliary | assistant horizontal groove was formed, it deform | transforms so that the edge part by the side of the auxiliary | assistant horizontal groove of a block may turn over at the time of braking of a tire mounting vehicle, and abrasion resistance will also fall. However, in the embodiment, since the groove and the concave portion are not formed in the tread tread 10, the tread tread 10 of the land portion 20 is stably grounded, and thus the wear resistance can be improved.

  Further, the deep groove portion 50 has a groove bottom 40c of the shallow groove portion 40 as an upper end and is recessed more inward in the tire radial direction TR than the shallow groove portion 40, so that the tire diameter with the groove bottom 40c of the shallow groove portion 40 as the lower end in the circumferential groove 30 The volume of the circumferential groove 30 is increased as compared with the case where a protrusion protruding outward in the direction TR is formed. For this reason, drainage can be further improved.

  In the embodiment, the side wall 40a of the shallow groove portion 40 passes through the circumferential groove 30 side end of the land portion 20 in the tread width direction cross section, and the distance CP between the tire equator line CL and the straight line PL is a groove of the shallow groove portion 40. It inclines so that it may become long as it goes to the bottom 40c. In the present embodiment, the shape of the side wall 40a of the shallow groove portion 40 is a half-moon shape recessed inward in the tire radial direction TR in the cross section in the tread width direction. According to this, as the wear progresses and the block rigidity of the land portion 20 becomes high, the edge component by the shallow groove portion 40 and the deep groove portion 50 can be gradually exhibited. For this reason, more stable braking performance can be exhibited from the beginning of wear to after a certain amount of wear.

  In the embodiment, the deep groove portion 50 is more rectangular than the shallow groove portion 40 in the cross section in the tread width direction. According to this, even if the shallow groove portion 40 is worn with wear of the land portion 20, the edge component by the shallow groove portion 40 can be reliably ensured until the progress of wear reaches the deep groove portion 50. For this reason, more stable braking performance can be exhibited from the beginning of wear to after a certain amount of wear.

(6) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows. Specifically, the tire has been described as being a pneumatic tire 1 filled with air, nitrogen gas, or the like, but is not limited to this, and a solid tire that is not filled with air, nitrogen gas, or the like. May be.

  Moreover, although the shallow groove part 40 and the deep groove part 50 demonstrated as what extends so that it might curve along the tread width direction TW in tread tread surface view, it is not limited to this, For example, it has extended linearly. Also good. Note that the shape of the shallow groove portion 40 and the shape of the deep groove portion 50 are not necessarily limited to those described in the embodiment, and can be appropriately set according to the purpose. For example, the inner shallow groove 41 and the outer shallow groove 42 do not necessarily have to be continuous, and may be separated in the vicinity of the center point P1 of the shallow groove portion 40. Similarly, the inner deep groove 51 and the outer deep groove 52 may be separated in the vicinity of the center point P <b> 2 of the deep groove portion 50. In this case, the volume of the circumferential groove 31 is increased, and the drainage can be further improved.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1, 1A, 1B, 1C ... pneumatic tires, 10, 10A, 10B, 10C ... tread surface, 20 (21-25) ... land part, 30 (31-34) ... circumferential groove, 40 ... shallow groove part (first) 1 groove part), 40a ... side wall, 40b ... deepest part, 40c ... groove bottom, 41 ... inner shallow groove, 41a ... outer convex part, 41p ... end part, 42 ... outer shallow groove, 42a ... outer convex part, 42p ... end 50, deep groove portion (second groove portion), 50a, side wall, 50b, groove bottom, 51, inner deep groove, 51a, outer convex portion, 51p, end portion, 52, outer deep groove, 52a, outer convex portion, 52p. End, 60 (61-65) ... auxiliary transverse groove

Claims (3)

With a rib-like land extending in the tire circumferential direction,
A tire formed with a circumferential groove adjacent to the land portion and extending in the tire circumferential direction,
The tread surface of the land portion is in a state where a normal load is applied to the tire, and in a state where the tire is in contact with the road surface, a smooth surface without a gap is formed,
The circumferential groove is
A first groove formed between the land portions adjacent to each other;
A second groove portion formed between the land portions adjacent to each other and adjacent to each other in the tire circumferential direction;
The second groove portion has a groove bottom of the first groove portion as an upper end and is recessed more inward in the tire radial direction than the first groove portion ,
Of the first groove portion and the second groove portion, at least a side wall of the first groove portion passes through the circumferential groove side end of the land portion in a cross-sectional view along the tread width direction and the tire radial direction, and the tire The tire which inclines so that the distance with the straight line parallel to an equator line may become long as it goes to the deepest part of the said 1st groove part . The shape of the first groove sidewall of, in the cross section, a tire according to claim 1 is a half-moon shape which is recessed on the inner side in the tire radial direction. Tread of the land portion, tire according to claim 1 or 2 extending in the tire circumferential direction without grooves and recesses are formed.

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