Abstract:
This pneumatic tire has a plurality of rib grooves ( 510 ) that extend in the direction of tread width formed in the tire peripheral direction (DC), and is provided with shoulder land sections ( 500 ) demarcated by the rib grooves ( 510 ). A plurality of hook-shaped sipes ( 600 ) are formed at the shoulder land sections ( 500 ). The hook-shaped sipes ( 600 ) have: a peripheral direction sipe section ( 610 ) extending along the tire peripheral direction; and a hook-shaped sipe section ( 620 ) that is continuous with the peripheral direction sipe section ( 610 ) and extends along the direction of tread width. A line (L 1 ) of extension along the hook-shaped sipe sections ( 620 ) intersects the line (L 2 ) of extension of the rib grooves ( 510 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a tire including a block-like land portion partitioned by a lug groove extending in a tread widthwise direction. 
       BACKGROUND ART 
       [0002]    Conventionally, in a pneumatic tire (hereinafter, referred to as tire) mounted on a passenger vehicle, for example, it has been proposed various tread patterns aiming to achieve the coexistence of two performances that are, generally, in trade-off relation such as improving maneuverability while ensuring a wear resistance. 
         [0003]    For example, it is known a tire having a plurality of sipings with the length of 2 to 10 mm regularly formed on a block-like land portion to improve cornering performance while ensuring a wear resistance (refer to Patent Literature 1). 
         [0004]    According to such a tire, the rigidity of the land portion is appropriately lowered by the plurality of sipings, and thus uneven wear is prevented and a wear resistance can be ensured. Further, with the plurality of sipings and short fibers contained in rubber that forms the land portion, cornering performance on an ice or snow road, in particular, is improved. 
         [0005]    Meanwhile, in recent years, as the global warming and the like accelerate, there is more demand for energy-saving of automobiles than ever. In such a circumstance, tires are demanded for further reducing rolling resistance. 
         [0006]    As a method of reducing the rolling resistance of a tire, it is considered to reduce the thickness of rubber of a tread (a tread gauge). However, when the tread gauge is made thinner, the depth of a groove that is formed on the tread cannot be made as deep as before, thus causing another problem. 
         [0007]    Specifically, there is a problem that the rigidity of a land portion that is partitioned by grooves becomes too high, and a wear resistance is reduced. Further, the shallow depth of the groove makes sufficient drainage from the ground-contact surface of the tread difficult, and reduces a hydroplaning resistance. 
       CITATION LIST 
     Patent Literature 
       [0008]    [Patent Literature 1] Japanese Patent Application Publication No. 2003-136916. 
       SUMMARY OF INVENTION 
       [0009]    A first feature is summarized as a tire (pneumatic tire  10 ) comprising high-angle grooves (high-angle grooves  100 ) in a tire circumferential direction (tire circumferential direction D C ) formed in a plural on a central region (central region Ac) in a tread widthwise direction (tread widthwise direction D T ), wherein a groove depth (groove depth D 1 ) of each of the high-angle grooves is 6 mm or less, each of angles (θ 1 ) formed by the each of high-angle grooves and the tire circumference direction is 15 degrees or less in view of a tread surface, a relation of W/D 1 ≦2.0 is satisfied where D 1  denotes the groove depth of each of the high-angle grooves and W denotes a width in the tread widthwise direction of a land portion adjacent to the high-angle grooves. 
         [0010]    In the first feature, each of the high-angle grooves may include a first straight groove portion (straight groove portion  110 ) which is a linear groove that is inclined toward one end side in the tread widthwise direction and a second straight groove portion (straight groove portion  160 ) which is a linear groove that is inclined toward the other end side in the tread widthwise direction. 
         [0011]    In the first feature, an end (end  111 ) at a side of a tire equator line (tire equator line CT) of the first straight groove portion may communicate to an end (end  161 ) at a side of the tire equator line of the second straight groove portion. 
         [0012]    In the first feature, a low-angle groove (low-angle groove  200 ) may be communicated to any one of ends (end  112 , end  162 ) of the first straight groove portion and the second straight groove portion at a side of a tread shoulder, the low-angle groove has an angle (θ 2 ) formed with the tire circumferential direction higher than that of the first straight groove portion, a circumferential groove (circumferential groove  300 ) may be formed at a portion where the low-angle groove is formed, and a groove depth (groove depth D 2 ) of the low-angle groove may be deeper than a groove depth (groove depth D 3 ) of the circumferential groove. 
         [0013]    In the first feature, the circumferential groove may include an inclined groove portion (inclined groove portion  310 ) which has a groove depth becomes larger as going from a side of a tire equator line to the tread shoulder and a groove bottom portion (groove bottom portion  360 ) which has a groove depth deeper than that of the inclined groove portion. 
         [0014]    In the first feature, a groove width (groove width GW 1 ) on an end of the first straight groove portion at a side of a tire equator line may be narrower than a groove width (groove width GW 2 ) on an end of the second straight groove portion at the side of the tire equator line. 
         [0015]    A second feature is summarized as a tire (pneumatic tire  10 ) comprising a block-like land portion (shoulder land portion  500 ) partitioned by a lug groove (lug groove  510 ), the lug groove extending in a tread widthwise direction (tread widthwise direction D T ) being formed in plural number in a tire circumferential direction (tire circumferential direction D C ), wherein a plurality of hook-like sipings (hook-like sipings  600 ) are formed on the block-like land portion, each of the hook-like sipings includes: a circumferential siping portion (circumferential siping portion  610 ) that extends along the tire circumferential direction and a hook-like siping portion (hook-like siping portion  620 ) that communicates to the circumferential siping portion and extends along the tread widthwise direction, and an extended line (extended line L 1 ) along the hook-like siping portion intersects with an extended line (extended line L 2 ) along the lug groove. 
         [0016]    In the second feature, the hook-like sipings may be formed in a plural number in the tread widthwise direction within the block-like land portion. 
         [0017]    In the second feature, the hook-like sipings may be formed in a plural number in the tire circumferential direction within the block-like land portion. 
         [0018]    In the second feature, the hook-like siping portion may extend from the circumferential siping portion toward an outer side in the tread widthwise direction. 
         [0019]    In the second feature, the depth of the lug groove may be 6 mm or less. 
         [0020]    In the second feature, the block-like land portion may be provided in a tread shoulder. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS  
         [0021]    [ FIG. 1 ]  FIG. 1  is a schematic perspective view of a pneumatic tire  10  according to an embodiment. 
           [0022]    [ FIG. 2 ]  FIG. 2  is a schematic front view of the pneumatic tire  10  according to the embodiment. 
           [0023]    [ FIG. 3 ]  FIG. 3  is a sectional view of the pneumatic tire  10 , which is taken along a line F 3 -F 3  shown in  FIG. 2 . 
           [0024]    [ FIG. 4 ]  FIG. 4  is an enlarged view of an F 4  portion shown in  FIG. 2 . 
           [0025]    [ FIG. 5 ]  FIG. 5  is an enlarged view of an F 5  portion shown in  FIG. 2 . 
           [0026]    [ FIG. 6 ]  FIG. 6  is a sectional view of a low-angle groove  200 , which is taken along a line F 6 -F 6  shown in  FIG. 5 . 
           [0027]    [ FIG. 7 ]  FIG. 7  is an enlarged view of an F 7  portion shown in  FIG. 2 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    Next, a tire (a pneumatic tire) according to an embodiment will be explained with reference to drawings. It is noted that, in the following description of the drawings, the same or similar reference numerals are used to designate the same or similar portions. However, it should be appreciated that the drawings are schematically shown and the ratio and the like of each dimension are different from the real ones. 
         [0029]    Accordingly, specific dimensions and the like should be determined in consideration of the explanation below. Moreover, among the drawings, the respective dimensional relations or ratios may differ. 
       (1) Overall Schematic Configuration of Tire 
       [0030]      FIG. 1  is a schematic perspective view of a pneumatic tire  10  according to the present embodiment.  FIG. 2  is a schematic front view of the pneumatic tire  10 . 
         [0031]    As shown in  FIG. 1  and  FIG. 2 , on the pneumatic tire  10 , a high-angle groove  100 , a low-angle groove  200 , and a circumferential groove  300  are formed. It is noted that the pneumatic tire  10  may be filled with, instead of air, an inert gas such as nitrogen gas. 
         [0032]    The high-angle groove  100  is formed in a central region Ac in a tread widthwise direction D T . The central region Ac is a region including a tire equator line CT passing through the center in the tread widthwise direction D T  of the pneumatic tire  10 , and is assumed to mean a region of one-third of the tread width in a state where a normal load is applied to the pneumatic tire  10  set to have a normal internal pressure regulated by the JATMA and the like. 
         [0033]    The high-angle groove  100  is formed in a plural number along a tire circumferential direction D C . The high-angle groove  100  is configured so that the high-angle groove  100  is a groove such that an angle formed with the tread widthwise direction is 75 degrees or more in view of a tread surface. That is, the high-angle groove  100  is a groove such that an angle θ 1  (see  FIG. 4 ) formed with the tire circumferential direction DC (specifically, the tire equator line CT) is 15 degrees or less. 
         [0034]    The low-angle groove  200  communicates to the high-angle groove  100 . The low-angle groove  200  has a larger angle θ 2  formed with the tire circumferential direction D C  (specifically, the tire equator line CT) than that of the high-angle groove  100 . That is, the low-angle groove  200  is a groove with a smaller angle formed with the tread widthwise direction D T  than that of the high-angle groove  100 . 
         [0035]    The circumferential groove  300  is a linear groove extending along the tire circumferential direction D C . The circumferential groove  300  is formed to overlap a part where the low-angle groove  200  is formed. That is, the low-angle groove  200  is formed to extend to the circumferential groove  300 . 
         [0036]    Further, at the outer side in the tread widthwise direction of the circumferential groove  300 , a land portion  400  that is linear and extending along the tire circumferential direction D C , is formed. The width in the tread widthwise direction D T  of the land portion  400  is narrower than the width in the tread widthwise direction D T  of the circumferential groove  300 , and at the further outer side in the tread widthwise direction D T  of the land portion  400 , a shoulder land portion  500  that is formed at the outermost side in the tread widthwise direction D T , is formed. 
       (2) Shape of Groove 
       [0037]    Next, shapes of the high-angle groove  100 , the low-angle groove  200 , and the circumferential groove  300  will be described with reference to  FIG. 3  to  FIG. 6 .  FIG. 3  is a sectional view of the pneumatic tire  10 , which is taken along a line F 3 -F 3  shown in  FIG. 2 .  FIG. 4  is an enlarged view of an F 4  portion shown in  FIG. 2 .  FIG. 5  is an enlarged view of an F 5  portion shown in  FIG. 2 .  FIG. 6  is a sectional view of the low-angle groove  200 , which is taken along a line F 6 -F 6  shown in  FIG. 5 . 
       (2.1) High-Angle Groove  100   
       [0038]    A groove depth D 1  (see  FIG. 3 ) of the high-angle groove  100  is 6 mm or less. Further, a thickness T (the tread gauge) of tread rubber of the pneumatic tire  10  is 10 mm and thinner than that of a general pneumatic tire. It is noted that the thickness T is a distance from the ground-contact surface of the tread to an outermost layer of a crossing belt layer  30  in the tire radial direction. Such a pneumatic tire  10  with a thin tread gauge has characteristics that rolling resistance is lower than that of a general pneumatic tire. 
         [0039]    The high-angle groove  100  is formed in a plural number in the central region Ac in the tread widthwise direction D T . The high-angle groove  100  is a groove such that an angle formed with the tread widthwise direction D T  is large (high angle) and runs along the tire circumferential direction D C . Specifically, in the high-angle groove  100 , the angle θ 1  formed with the tire circumferential direction D C  is 15 degrees or less in view of the tread surface. However, the high-angle groove  100  preferably has a certain angle (for example, 5 degrees or more) with respect to the tire circumferential direction D C  (the tire equator line CT). 
         [0040]    Further, the groove depth D 1  of the high-angle groove  100  and a width W in the tread widthwise direction D T  of a land portion  60  that is adjacent to the high-angle groove  100  satisfies the relation of W/D 1 ≦2.0. That is, as described above, since the thickness T of the tread rubber of the pneumatic tire  10  is 10 mm or less, the value of the groove depth D 1  is smaller than that of the general pneumatic tire. Therefore, the width W of the land portion  60  cannot have a very large value, either, and the land portion  60  has a long and narrow shape. 
         [0041]    In the present embodiment, the high-angle groove  100  is in a V-lettered shape configured by two linear groove portions. Specifically, the high-angle groove  100  is configured by a straight groove portion  110  and a straight groove portion  160 . 
         [0042]    The straight groove portion  110  (the first straight groove) is a linear groove that is inclined toward one end side (for example, the outer side when mounted on a vehicle) in the tread widthwise direction D T . The straight groove portion  160  (the second straight groove) is a linear groove that is inclined toward the other end side (for example, the inner side when mounted on a vehicle) in the tread widthwise direction D T . 
         [0043]    An end  111  at the side of the tire equator line CT of the straight groove portion  110  communicates to an end  161  at the side of the tire equator line CT of the straight groove portion  160 . 
         [0044]    A groove width GW 1  on the end  111  of the straight groove portion  110  is narrower than a groove width GW 2  on an end  112  of the straight groove portion  160 . Specifically, the groove width GW 1  is 2.0 mm or more and the groove width GW 2  is from 0.4 mm to a width that is the same as the groove width GW 1 . It is noted that, as shown in  FIGS. 1 ,  2 , and  4 , the high-angle groove  100  having a shape such that the groove width on an end at the side of the tire equator line CT of the straight groove portion  160  is narrower than the groove width on an end at the side of the tire equator line CT of the straight groove portion  110 , is also formed. In the present embodiment, the high-angle groove  100  of which the groove width on the end at the side of the tire equator line CT of the straight groove portion  110  is narrow, and the high-angle groove  100  of which the groove width on the end at the side of the tire equator line CT of the straight groove portion  160  is narrow, are repeated alternately along the tire circumferential direction D C . 
       (2.2) Low-Angle Groove  200   
       [0045]    The low-angle groove  200  communicates to the high-angle groove  100 . Specifically, the low-angle groove  200  communicates to the end  112  (an end  162 , see  FIG. 2 ) at a tread shoulder side of the straight groove portion  110  (and the straight groove portion  160 ). 
         [0046]    The low-angle groove  200  is a groove such that an angle formed with the tread widthwise direction D T  is small (a low angle) and runs along the tread widthwise direction D T . Specifically, the low-angle groove  200  is a groove such that the angle θ 2  formed with the tire circumferential direction D C  is 45 degrees or more in view of the tread surface. That is, the low-angle groove  200  is a groove such that the angle θ 2  formed by the low-angle groove  200  with the tire circumferential direction D C  is larger than the angle θ 1  formed by the straight groove portion  110  with the tire circumferential direction D C  and more gently inclined relative to the tread widthwise direction D T  (that is, of a low angle). 
       (2.3) Circumferential Groove  300   
       [0047]    The circumferential groove  300  is formed at an outer side in the tread widthwise direction D T  of the low-angle groove  200 . The circumferential groove  300  is formed at an outer side in the tread widthwise direction D T  from the central region Ac. The circumferential groove  300  is configured by an inclined groove portion  310 , a notch groove portion  320 , and a groove bottom portion  360 . 
         [0048]    The inclined groove portion  310  is inclined so that a groove depth D 3  is deeper as going from the side of the tire equator line CT to the tread shoulder. In the present embodiment, the inclined groove portion  310  is not linear but has a gently curved shape in a cross-sectional view along the tread widthwise direction D T . 
         [0049]    The notch groove portion  320  is a notched groove that is formed on the inclined groove portion  310 . An outer end in the tread widthwise direction D T  of the notch groove portion  320  communicates to the groove bottom portion  360 . Further, an inner end in the tread widthwise direction D T  of the notch groove portion  320  terminates within the inclined groove portion  310 . The notch groove portion  320  is formed between low-angle grooves  200  that are adjacent in the tire circumferential direction D C . 
         [0050]    The groove bottom portion  360  is formed at an outer end in the tread widthwise direction D T  within the circumferential groove  300 . The groove depth of the groove bottom portion  360  is deeper than those of the low-angle groove  200  and the inclined groove portion  310 . Specifically, a groove depth D 2  of the low-angle groove is deeper than a groove depth D 3  of the circumferential groove  300 , specifically, the inclined groove portion  310 . That is, the low-angle groove  200  is further formed within the inclined groove portion  310  of the circumferential groove  300 . Further, the groove depth of the groove bottom portion  360  of the circumferential groove  300  is still deeper than that of the low-angle groove  200 , and the groove depth is deeper in an order of the inclined groove portion  310 , the low-angle groove  200 , and the groove bottom portion  360 . 
       (3) Shape of Shoulder Land Portion  500   
       [0051]    Next, the shape of the shoulder land portion  500  will be described.  FIG. 7  is an enlarged view of an F 7  portion shown in  FIG. 2 . 
         [0052]    As shown in  FIG. 7 , the shoulder land portion  500  is a block-like land portion that is formed at the outermost side in the tread widthwise direction D T . In the present embodiment, the shoulder land portion  500  constitutes the block-like land portion that is provided in a tread shoulder. The shoulder land portion  500  is a land portion that is partitioned by a lug groove  510  extending in the tread widthwise direction D T . It is noted that, in the present embodiment, it is assumed that the tread shoulder indicates a region at an outer side in the tread widthwise direction D T  other than the central region Ac. 
         [0053]    The lug groove  510  is formed in a plural number in the tire circumferential direction D C . Thus, the lug groove  510  is formed in a plural number in the tire circumferential direction D C , and thereby the shoulder land portion  500  is also formed in a plural number in the tire circumferential direction D C . The depth of the lug groove  510  is 6 mm or less, similarly to the high-angle groove  100  and the like. Further, the lug groove  510  is adjacent to the land portion  400  and communicates to a circumferential narrow groove  520  extending along the tire circumferential direction D C . 
         [0054]    On the shoulder land portion  500 , a plurality of hook-like sipings  600  are formed. Specifically, the hook-like siping  600  is formed in a plural number within the shoulder land portion  500  in the tread widthwise direction D T  and the tire circumferential direction D C . More specifically, three rows of the hook-like sipings  600  are formed in the tread widthwise direction D T  and four rows of the hook-like sipings  600  are formed in the tire circumferential direction D C . 
         [0055]    The hook-like siping  600  has a circumferential siping portion  610  and a hook-like siping portion  620 . The circumferential siping portion  610  is a linear shape extending along the tire circumferential direction D C . 
         [0056]    The hook-like siping portion  620  communicates to the circumferential siping portion  610  and is a linear shape extending along the tread widthwise direction D T . Specifically, an end of the hook-like siping portion  620  communicates to an end of the circumferential siping portion  610 . That is, the circumferential siping portion  610  and the hook-like siping portion  620  communicate to each other without intersecting with each other. The hook-like siping portion  620  extends toward the outer side in the tread widthwise direction D T  from the circumferential siping portion  610 . 
         [0057]    It is noted that the hook-like siping  600  is a narrow groove having a width such as being crushed to be closed (both sidewalls contact with each other) when the shoulder land portion  500  comes into contact with the road surface. The groove width of the hook-like siping  600  is preferably 0.4 mm to 1.2 mm. 
         [0058]    Further, the hook-like siping portion  620  extends in a direction to intersect with the lug groove  510 . Specifically, the hook-like siping portion  620  is formed so that an extended line L 1  along the hook-like siping portion  620  intersects with an extended line L 2  along the lug groove  510 . 
       (4) Advantageous and Effect 
       [0059]    According to the pneumatic tire  10 , the groove depth D 1  of the high-angle groove  100  is 6 mm or less. That is, since the thickness T of the tread rubber of the pneumatic tire  10  is thinner than that of the general pneumatic tire, rolling resistance is reduced. Further, the angle θ 1  formed by the high-angle groove  100  with the tire circumferential direction D C  is 15 degrees or less, and thus drainage performance of rainwater that has entered the high-angle groove  100  is good. That is, a hydroplaning resistance can be ensured. 
         [0060]    Further, the groove depth D 1  of the high-angle groove  100  and the width W in the tread widthwise direction D T  of the land portion  60  that is adjacent to the high-angle groove  100  satisfies the relation of W/D 1 ≦2.0. That is, since the width of the land portion  60  narrows down in the tread widthwise direction D T , the land portion  60  at breaking is prevented from being deformed to turn up in the tire circumferential direction D C , and braking performance is improved. Further, the width of the land portion  60  is narrow, and thus reduces forced wear in the central region Ac (wear resulting from external force (braking force and the like) acting upon the pneumatic tire  10 ). 
         [0061]    That is, according to the pneumatic tire  10 , even when the thickness T of the tread rubber is reduced, a tire life and a hydroplaning resistance as good as those of the conventional tire are provided. 
         [0062]    Further, in the present embodiment, the high-angle groove  100  forms a V-lettered shape with the straight groove portion  110  and the straight groove portion  160 . Specifically, the end  111  of the straight groove portion  110  communicates to the end  161  of the straight groove portion  160 . Therefore, rainwater that has entered the central region Ac can be efficiently drained. It is noted that, since the groove width GW 1  of the straight groove portion  110  is narrower than the groove width GW 2  of the straight groove portion  160 , it is possible to prevent a great decrease in rigidity of the land portion  60  around a portion communicating between the straight groove portion  110  and the straight groove portion  160 . 
         [0063]    Further, the low-angle groove  200  communicates to the high-angle groove  100  and the circumferential groove  300  is formed in a portion where the low-angle groove  200  is formed. Further, the groove depth D 2  of the low-angle groove  200  is deeper than the groove depth D 3  of the circumferential groove  300 . Thus, it becomes possible to preferentially guide rainwater that has entered the central region Ac to the low-angle groove  200  and the circumferential groove  300  although the groove width of the high-angle groove  100  is narrow, thus making it possible to further improve drainage performance. 
         [0064]    Further, the circumferential groove  300  has the inclined groove portion  310  and the groove bottom portion  360  that has a groove depth deeper than that of the inclined groove portion  310  and extends in the tire circumferential direction D C , and thus is further advantageous in terms of drainage performance of rainwater that has entered the central region Ac. 
         [0065]    It is noted that, owing to the low-angle groove  200 , an angle formed by the low-angle groove  200  with the circumferential groove  300  in view of the tread surface is large and it is avoided that a land portion block in a portion where the low-angle groove  200  communicates to the circumferential groove  300  becomes tapered, thus making it possible to prevent a decrease in rigidity or loss of the land portion block. 
         [0066]    The tread pattern like that of the pneumatic tire  10  can be achieved because of a special setting such that the groove depth of the high-angle groove  100 , the low-angle groove  200 , and the circumferential groove  300  is 6 mm or less. In the case of a general groove depth (10 mm, for example), the rigidity of the land portion  60  is too weak, and thus it is difficult to use such a tread pattern in practice. It is noted that, such a tread pattern can be preferably used as a tread for retreading in which only a worn tread portion is changed. 
         [0067]    Further, according to the pneumatic tire  10 , a plurality of the hook-like sipings  600  are formed on the shoulder land portion  500 . Therefore, even when the groove depth of the lug groove  510  is as shallow as 6 mm or less and compression rigidity of the shoulder land portion  500  is likely to become extremely high, the compression rigidity is prevented from becoming high. That is, even when the rubber thickness of the tread is reduced, a wear resistance similar to that of the conventional tire can be ensured. 
         [0068]    Further, the hook-like siping portion  620  is formed so that the extended line L 1  along the hook-like siping portion  620  intersects with the extended line L 2  along the lug groove  510 . Therefore, the rainwater that has entered between the shoulder land portion  500  and the road surface goes through the hook-like siping portion  620  from the circumferential siping portion  610  to be easily drained to the outer side in the tread widthwise direction D T  of the pneumatic tire  10 . That is, even the pneumatic tire  10  with the shallow groove depth is enabled to drain sufficiently from the ground-contact surface of the tread, and can ensure the hydroplaning resistance. 
         [0069]    In particular, the rainwater that has entered the central region Ac is guided to the circumferential groove  300  through the high-angle groove  100  and the low-angle groove  200  and drained by the circumferential groove  300 . Further, on the outer side in the tread widthwise direction DT of the circumferential groove  300 , the land portion  400  extending along the tire circumferential direction DC is provided. Therefore, the rainwater that has entered the central region Ac is drained mainly by the circumferential groove  300 , and thus the lug groove  510 , the circumferential narrow groove  520 , and the hook-like siping  600  may mainly drain the rainwater that has entered between the shoulder land portion  500  and the road surface. 
         [0070]    Further, since the hook-like siping  600  terminates within the shoulder land portion  500  without communicating to the lug groove  510  or the circumferential narrow groove  520 , it is possible to also prevent deformation where the shoulder land portion  500  turns up from a point at the end of the hook-like siping  600 . 
       (5) Other Embodiments 
       [0071]    As described above, the content of the present invention is disclosed through the embodiment. However, it should not be interpreted that the statements and drawings constituting a part of the present disclosure limit the present invention. From this disclosure, a variety of alternate embodiments, examples, and applicable techniques will become apparent to one skilled in the art. 
         [0072]    For example, the embodiment can be changed as follows: Although the low-angle groove  200  and the circumferential groove  300  are formed in the above-described embodiment, the low-angle groove  200  and the circumferential groove  300  may not necessarily be formed. 
         [0073]    In the above-described embodiment, both the straight groove portion  110  and the straight groove portion  160  that constitute the high-angle groove  100  are linear; however, the high-angle groove  100  may not be linear, but may be in a shape of gently curving toward the outer side in the tread widthwise direction D T , for example. 
         [0074]    Further, the high-angle groove  100  may not necessarily be in a V-lettered shape such that the straight groove portion  110  communicates to the straight groove portion  160 . 
         [0075]    In the above-described embodiment, the hook-like siping  600  is formed in a plural number in the tread widthwise direction D T  and in the tire circumferential direction D C  within the shoulder land portion  500 , and the hook-like siping  600  is preferably formed in a plural number; however, may not necessarily be formed in a plural number in the tread widthwise direction D T  or the tire circumferential direction D C . Further, the hook-like siping portion  620  may not necessarily extend toward the tread widthwise direction D T  and the hook-like siping  600  may be formed on the block-like land portion other than the shoulder land portion  500 . 
         [0076]    As described above, needless to say, the present invention includes various embodiments and the like not described here. Therefore, the technical range of the present invention is to be defined only by the inventive specific matter according to the adequate claims from the above description. 
         [0077]    In addition, the entire content of Japanese Patent Application No. 2011-171167 (filed on Aug. 4, 2011) is incorporated in the present description by reference. 
       INDUSTRIAL APPLICABILITY 
       [0078]    According to a characteristic of the present invention, it is possible to provide a tire that has a wear resistance and a hydroplaning resistance similar to those of the conventional tire even when the rubber thickness of the tread is reduced down.