Patent Publication Number: US-2023147893-A1

Title: Tire

Description:
TECHNICAL FIELD 
     The present technology relates to a tire with a tread pattern. 
     BACKGROUND ART 
     Tires, especially winter tires with improved running performance on snowy road surfaces, often have a block pattern in which a tread portion is divided into a plurality of blocks by circumferential grooves extending continuously in the tire circumferential direction and lateral grooves extending in the tire width direction. This pattern causes gripping force in the circumferential direction to be obtained by shear force of a snow column compacted in the lateral groove, driving performance and braking ability on the snowy road to be exhibited, lateral gripping force to be obtained by the shear force of the snow column compacted in the lateral groove, and steering stability on the snowy roads to be improved. 
     On the other hand, winter tires, which pass the place where snow melts and a water film is formed on the road surface, preferably have improved wet performance including drainage properties. To improve the wet performance, as a tread pattern that can efficiently drain the water accumulated in front of the rolling tire, a tread pattern having an inclined groove group in which a plurality of sets of inclined grooves, which extends from the starting end toward both sides in the tire width direction and toward the same side in the tire circumferential direction to the pattern end of the tread portion, is disposed in the tire circumferential direction may be used. The inclination angle of the inclined grooves with respect to the tire circumferential direction gradually increases from the starting end toward an outer side in the tire width direction and is close to approximately 90 degrees with respect to the tire circumferential direction at the tread pattern end. 
     For example, as a pneumatic tire that can provide improved braking on snow performance and wet performance, a known tread pattern in which a V-shaped crossing groove having a V-shape that projects in the tire circumferential direction, crosses the tread portion in the tire width direction, and opens to both left and right tread edge portions is provided, and a plurality of the V-shaped crossing grooves is arranged at predetermined intervals in the tire circumferential direction while directions of the V-shapes are aligned (Japan Unexamined Patent Publication No. 2015-081076 A). 
     Furthermore, for a tire that can provide wet road performance and icy and snowy road performance in a highly compatible manner, there is a known tread pattern in which a circumferential groove extending in the tire circumferential direction is formed, and a plurality of high-angle inclined grooves, which extends from the central portion of the tread width direction to an outer side in the tread width direction and is inclined with respect to the tire circumferential direction, is formed (Japan Patent No. 5860625 B). In this tread pattern, a low-angle inclined groove extending from the circumferential groove to an inner side in the tread width direction and having a smaller angle on the acute angle side formed with the tread width direction than the high-angle inclined groove is formed, and the high-angle groove intersects a high-angle groove formed on the opposite side with respect to the tire equator line. 
     SUMMARY 
     Japan Unexamined Patent Publication No. 2015-081076 A describing the pneumatic tire including the V-shaped crossing groove and Japan Patent No. 5860625 B describing the pneumatic tire including the high-angle inclined groove do not describe how the inclination angle of each groove with respect to the tire circumferential direction is preferably set at each position in the tire width direction. 
     To improve both snow performance and wet performance as compared to the related art, appropriately setting an inclination angle of the inclined groove at each position in the tire width direction is preferable. 
     The present technology provides a tire with improved snow performance and wet performance in a tread pattern including an inclined groove group in which a plurality of sets of inclined grooves, which extends from a starting end of a center region including a tire equator line toward both sides in a tire width direction and toward the same side in a tire circumferential direction to a pattern end of a tread portion, is disposed in the tire circumferential direction. 
     One aspect of the present technology is a tire. The tire includes a tread pattern including an inclined groove group in which a plurality of sets of inclined grooves, which extends from a starting end in a center region including a tire equator line toward both sides in a tire width direction and toward a first side in a tire circumferential direction across the tire equator line to a pattern end of a tread portion, is disposed in the tire circumferential direction. 
     A periphery distance from the tire equator line to the pattern end at one side in the tire width direction is L, an inclination angle of the inclined groove with respect to the tire circumferential direction is 
     (a) greater than 40 degrees and 50 degrees or less in a first range from the starting end to a position separated in the tire width direction by 35% of the periphery distance L, 
     (b) greater than 50 degrees and 65 degrees or less in a second range from an outer side in the tire width direction of the position separated from the tire equator line in the tire width direction by 35% of the periphery distance L to a position separated from the tire equator line in the tire width direction by 50% of the periphery distance L, 
     (c) greater than 65 degrees and 80 degrees or less in a third range from an outer side in the tire width direction of the position separated from the tire equator line in the tire width direction by 50% of the periphery distance L to a position separated from the tire equator line in the tire width direction by 70% of the periphery distance L, and 
     (d) greater than 80 degrees and 90 degrees or less in a fourth range from an outer side in the tire width direction of the position separated from the tire equator line in the tire width direction by 70% of the periphery distance L to a position separated from the tire equator line in the tire width direction by 100% of the periphery distance L, and 
     a circumferential-direction distance along the tire circumferential direction from the starting end to a terminating end of the inclined groove in the pattern end being from 60% to 90% of a width-direction distance along the tire width direction from the starting end to the terminating end. 
     Preferably, the inclined grooves extend to the pattern end without intersecting a circumferential main groove which extends in the tire circumferential direction and goes around a tire circumference, and 
     block land portions, which are each provided between adjacent inclined grooves adjacent in the tire circumferential direction of the inclined grooves disposed in each of half-tread regions on both sides of the tire equator line, contact both of the adjacent inclined grooves. 
     The tread pattern preferably includes two connecting grooves that connect two adjacent inclined grooves adjacent in the tire circumferential direction in the inclined groove group within a range separated from the tire equator line by from 15 to 55% of the periphery distance L in the tire width direction. 
     The connecting grooves preferably extend toward the first side and toward an inner side in the tire width direction. 
     Preferably, a portion of the connecting grooves crosses one of the adjacent inclined grooves, extends to a region of a land portion defined by the one of the adjacent inclined grooves, and is closed. 
     Preferably, each of the inclined grooves includes a crossing portion that crosses between two inclined grooves extending to an outer side in the tire width direction different from an outer side in the tire width direction in which each of the inclined grooves extends, and the crossing portion further crosses the tire equator line. 
     Preferably, each of the inclined grooves includes a crossing portion that crosses between two inclined grooves extending to an outer side in the tire width direction different from an outer side in the tire width direction in which each of the inclined grooves extends, and the crossing portion preferably further crosses the tire equator line, 
     the connecting grooves include a first connecting groove located at a side of the tire equator line and a second connecting groove located at an outer side of the first connecting groove in the tire width direction, and 
     the first connecting groove, the second connecting groove, and the crossing portion are inclined to the same side in the tire width direction from the tire circumferential direction, an inclination angle θC of the crossing portion with respect to the tire circumferential direction is greater than an inclination angle θA of the first connecting groove with respect to the tire circumferential direction, and the inclination angle θA is greater than an inclination angle θB of the second connecting groove with respect to the tire circumferential direction. 
     Preferably, the inclination angle θB is from 0.6 to 0.8 times the inclination angle θA, and the inclination angle θA is from 0.75 to 0.95 times the inclination angle θC. 
     Preferably, the tread pattern preferably includes a shallow connecting groove that connects the two adjacent inclined grooves adjacent in the tire circumferential direction in the inclined groove group within a range separated from the tire equator line by greater than 55% and 75% or less of the periphery distance L in the tire width direction, and the shallow connecting groove preferably has a groove depth from 40 to 50% of a groove depth of the adjacent inclined grooves at connection positions where the adjacent inclined grooves are connected to the shallow connecting groove. 
     Preferably, the tread pattern preferably includes a first block land portion surrounded by the adjacent inclined grooves, the crossing portion, and the first connecting groove and a second block land portion surrounded by the adjacent inclined grooves, the first connecting groove, and the second connecting groove between adjacent inclined grooves adjacent in the tire circumferential direction in the inclined groove group, and an area S 1  of the first block land portion is smaller than an area S 2  of the second block land portion. 
     The area S 1  is preferably from 75% to 85% of the area S 2 . 
     In a region of the first block land portion, a groove portion of one inclined groove of the inclined grooves at the starting end side from the crossing portion is preferably provided as a starting groove portion, and 
     a distance along the tire width direction between a position of a first end of the first block land portion located farthest from the starting groove portion at a side of the tire equator line and a connection position where the starting groove portion is connected to one of the adjacent inclined grooves contacting the first block land portion is L 1 , a distance along the tire width direction between the first end of the first block land portion and a second end of the first block land portion located at the outermost side in the tire width direction is LB 1 , and the distance L 1  is preferably from 25% to 35% of the distance LB 1 . 
     A distance from the starting end of the starting groove portion to the connection position is L 2 , and the distance L 2  is preferably from 40% to 45% of the distance LB 1 . 
     In a region of the second block land portion, a closed groove that extends from one of the adjacent inclined grooves and is closed without being connected to the other of the adjacent inclined grooves is preferably provided, and 
     a distance along the tire width direction between a third end of the second block land portion located farthest from the closed groove at the side of the tire equator line and a connection position where the closed groove is connected to the one of the adjacent inclined grooves is L 3 , and a distance along the tire width direction between the third end of the second block land portion and a fourth end of the second block land portion located at the outermost side in the tire width direction is LB 2 , and the distance L 3  is preferably from 25% to 35% of the distance LB 2 . 
     Preferably, a distance from a closed end of the closed groove to the connection position is L 4 , and the distance L 4  is from 40% to 45% of the distance LB 2 . 
     The tread pattern preferably includes a plurality of sipes provided in a region of a land portion between inclined grooves adjacent in the tire circumferential direction, and 
     a value obtained by dividing a total length (mm) of lengths projected in the inclination direction A, which is inclined at an angle α (α=0 or more and less than 360 degrees) with respect to the tire width direction, of all grooves provided in the tread pattern by (ground contact width×circumferential length) (mm 2 ) is ρg, a value obtained by dividing a total length (mm) projected in the inclination direction A of all the sipes provided in the tire by (ground contact width×circumferential length) (mm 2 ) is ρs, an average depth (mm) of grooves is Dg, a snow traction index STI is defined by the following Formula (1), 
       STI=−6.8+2202*ρ g+ 672*ρ s+ 7.6* Dg   (1), and
 
     a value of the snow traction index STI at the angle α=30 to 40 degrees is preferably from 104% to 110% of a value of the snow traction index STI at the angle α=0 degrees. 
     The above-described tire is capable of improving snow performance and wet performance at the same time. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a tire cross-sectional view illustrating a cross-section of a tire according to an embodiment. 
         FIG.  2    is a diagram illustrating an example of a tread pattern provided in a tread portion of the tire according to the embodiment. 
         FIG.  3    is a diagram illustrating an inclination angle of an inclined groove in the first to fourth ranges according to the embodiment. 
         FIG.  4 A  is a diagram illustrating inclination angles of a connecting groove and a crossing portion according to the embodiment, and  FIG.  4 B  is a diagram illustrating a block land portion of the tread pattern of the tire according to the embodiment. 
         FIGS.  5 A and  5 B  are diagrams illustrating the shape dimensions of a first block land portion and a second block land portion provided in the tread pattern of the tire according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a tire of an embodiment is described. The tire described below is, for example, a tire for a passenger vehicle. A tire for a passenger vehicle refers to a tire specified in Chapter A of the JATMA YEAR BOOK 2019 (standards of The Japan Automobile Tyre Manufacturers Association, Inc.). The tire can also be a small truck tire specified in Chapter B or a truck tire or bus tire specified in Chapter C. 
     The tire may be a pneumatic tire filled with air to exhibit tire performance, or a gas-filled tire filled with nitrogen, oxygen, carbon dioxide, or an inert gas instead of air. Further, instead of the gas-filled tire, the tire may be a run-flat tire that can exhibit tire performance and tire load support functions by disposing a resin support material in the tire cavity region in place of gas filling. 
     Tire circumferential direction described below refers to the direction (both rotation directions) to which a tread surface rotates in a case where a tire rotates about the tire rotation axis. Tire radial direction refers to the direction that extends radially orthogonal to the tire rotation axis. Outer side in the tire radial direction refers to the direction away from the tire rotation axis in the tire radial direction. Tire width direction refers to the direction parallel with the tire rotation axis direction. Outer side in the tire width direction refers to both directions away from a tire equator line of the tire. 
       FIG.  1    is a diagram illustrating a cross-section of the tire of an embodiment along the tire radial direction including a tire rotation axis.  FIG.  1    illustrates a cross-section on the right side with respect to a tire equator line CL, but the tire has a shape and structure that is axisymmetric with respect to the tire equator line CL in the cross-section. 
     A tire  10  illustrated in  FIG.  1    includes a carcass ply layer  12 , a belt layer  14 , and bead cores  16  as framework members or layers of framework members and mainly includes a tread rubber member  18 , side rubber members  20 , bead filler rubber members  22 , rim cushion rubber members  24 , and an innerliner rubber member  26  around the framework members. 
     The carcass ply layer  12  includes carcass ply members  12   a  and  12   b  that are formed from organic fibers covered with rubber and that are wound between the pair of bead cores  16  of an annular shape so as to b e formed into a toroidal shape. In the tire  10  illustrated in  FIG.  1   , the carcass ply layer  12  is made of the carcass ply members  12   a  and  12   b  but may also be made of a single carcass ply member. The belt layer  14  is provided on an outer side of the carcass ply layer  12  in the tire radial direction and is composed of two belt members  14   a  and  14   b . The belt layer  14  is constituted of rubber-covered steel cords. The steel cords are inclined at a predetermined angle of, for example, from 20 to 30 degrees with respect to the tire circumferential direction. A width in the tire width direction of the lower layer belt member  14   a  is greater than that of the upper layer belt member  14   b . The steel cords of the two belt members  14   a  and  14   b  are inclined in opposite directions. Accordingly, the belt members  14   a  and  14   b  are crossing layers serving to suppress expansion of the carcass ply layer  12  due to inflation air pressure. 
     The tread rubber member  18  is provided in an outer side of the belt layer  14  in the tire radial direction. The side rubber members  20  are connected to both end portions of the tread rubber member  18  and form sidewall portions. The tread rubber member  18  is made of two layers of rubber members, namely an upper layer tread rubber member  18   a  provided on the outer side in the tire radial direction and a lower layer tread rubber member  18   b  provided on the inner side in the tire radial direction. The rim cushion rubber members  24  are respectively provided at inner ends of the side rubber members  20  in the tire radial direction and come into contact with a rim on which the tire  10  is mountable. The bead filler rubber members  22  are provided on an outer side of the bead cores  16  in the tire radial direction and interposed between a portion of the carcass ply layer  12  before the carcass ply  12  is wound around the bead cores  16  and a portion of the carcass ply layer  12  that is wound around the bead cores  16 . The innerliner rubber member  26  is provided on the inner surface of the tire  10  facing a tire cavity region that is filled with air and is surrounded by the tire  10  and the rim. 
     In addition, the tire  10  includes a belt cover layer  28  formed from organic fiber covered with rubber that covers the belt layer  14  from the outer side in the tire radial direction of the belt layer  14 . 
     The tire  10  has such a tire structure, but the tire structure is not limited to the tire structure illustrated in  FIG.  1   . In  FIG.  1   , the groove cross section of a tread pattern  30  described below that is formed in the tread rubber member  18  is omitted. 
     Tread Pattern 
       FIG.  2    is a developed plan view illustrating an example of a tread pattern provided in a tread portion of the tire  10  according to the embodiment. The tread pattern  30  illustrated in  FIG.  2    includes an inclined groove  32  and a sipe  34 . 
     A plurality of the inclined grooves  32  is provided to form an inclined groove group. 
     As illustrated in  FIG.  2   , the inclined grooves  32  extend from a starting end  32   a  of a center region including the tire equator line CL toward both sides in the tire width direction and toward a first side in the tire circumferential direction (upper side of the paper in  FIG.  2   ) across the tire equator line CL to a pattern end PE of the tread portion. A plurality of sets of these inclined grooves is disposed in the tire circumferential direction at predetermined intervals. 
     Here, a center region refers to a region in the range from the tire equator line CL to positions separated therefrom on both sides in the tire width direction by 15% (preferably from 10 to 20%) of a periphery distance L that is from the tire equator line CL to the pattern end PE on one side in the tire width direction. 
     The starting end  32   a  of the inclined groove  32  is on the side opposite to the pattern end PE side which is a terminating end  32   b  of the inclined groove  32  with respect to the tire equator line CL in the tire width direction. Accordingly, the inclined grooves  32  cross the tire equator line CL in the middle of extending from the starting end  32   a  to the terminating end  32   b  of the pattern end PE. 
     The positions of the inclined grooves  32  in the tire circumferential direction are staggered between the inclined groove  32  located mainly at one side in the tire width direction with respect to the tire equator line CL and the inclined groove  32  mainly located at the other side in the tire width direction. Specifically, the starting end  32   a  of the inclined groove  32  located mainly on the other side in the tire width direction is located at an approximately intermediate position (position in the tire circumferential direction) between the starting ends  32   a  of two inclined grooves  32   a  adjacent in the tire circumferential direction which are located mainly on one side of the tire width direction. 
     The groove width of the inclined groove  32  gradually increases from the starting end  32   a  toward the terminating end  32   b . Further, the groove depth of the inclined groove  32  is gradually shallower from the starting end  32   a  toward the terminating end  32   b . The groove width of the inclined groove  32  is, for example, from 2.0 mm to 7.0 mm, and the groove depth thereof is, for example, from 7.5 mm to 6.5 mm. 
     The sipe  34  is provided in a region of a block land portion provided between two adjacent inclined grooves  32  adjacent in the tire circumferential direction in the inclined groove group. The sipe  34  has a wave-like shape and extends in a predetermined direction to improve snow performance. In the tread pattern  30  illustrated in  FIG.  2   , the sipe  34  has one branch portion at the bend point of the wave-like shape. The sipe  34  may be connected to the groove surrounding the block land portion or may be closed within the region of the block land portion. The distance between sipe wall surfaces of the sipe  34  is, for example, from 2.5 mm to 7.0 mm, and the depth of the sip e  34  is, for example, from 2.0 mm to 7.2 mm, and the sipe  34  can be distinguished from the inclined groove  32  by the width and depth. 
     Here, an inclination angle of the inclined groove  32  with respect to the tire circumferential direction is set as follows.  FIG.  3    is a diagram illustrating inclination angles of the inclined groove  32  in the first to fourth ranges described below. 
     (a) greater than 40 degrees and 50 degrees or less in a first range R 1  from the starting end  32   a  to a position separated in the tire width direction by 35% of the periphery distance L, 
     (b) greater than 50 degrees and 65 degrees or less in a second range R 2  from an outer side in the tire width direction of the position separated from the tire equator line CL in the tire width direction by 35% of the periphery distance L to a position separated from the tire equator line CL in the tire width direction by 50% of the periphery distance L (not including the position separated in the tire width direction by 35% of the periphery distance L), 
     (c) greater than 65 degrees and 80 degrees or less in a third range R 3  from an outer side in the tire width direction of the position separated from the tire equator line CL in the tire width direction by 50% of the periphery distance L to a position separated in the tire width direction by 70% of the periphery distance L (not including the position separated from the tire equator line CL in the tire width direction by 50% of the periphery distance L), and 
     (d) greater than 80 degrees and 90 degrees or less in a fourth range R 4  from an outer side in the tire width direction of the position separated from the tire equator line CL in the tire width direction by 70% of the periphery distance L to a position separated from the tire equator line CL in the tire width direction by 100% of the periphery distance L (not including the position separated in the tire width direction by 70% of the periphery distance L). 
     Here, the inclination angle is an angle of a straight line connecting center positions of the inclined grooves  34  at positions on both sides in the tire width direction defining each of the first to fourth ranges R 1  to R 4 , with respect to the tire circumferential direction. For example, the inclination angle in the first range R 1  is an inclination angle with respect to the tire circumferential direction of a straight line connecting the starting end  32   a  and a center position of the inclined groove  32  at the position separated from the tire equator line CL in the tire width direction by 35% of the periphery distance L, and the inclination angle in the second range R 2  is an inclination angle with respect to the tire circumferential direction of a straight line connecting the position separated from the tire equator line CL in the tire width direction by 35% of the periphery distance L and the position separated from the tire equator line CL in the tire width direction by 50% of the periphery distance L. 
     Furthermore, a circumferential-direction distance Y (see  FIG.  3   ) along the tire circumferential direction from the starting end  32   a  to the terminating end  32   b  of the inclined groove  32  in the pattern end PE is from 60% to 90% of a width-direction distance X (see  FIG.  3   ) along the tire width direction from the starting end  32   a  to the terminating end  32   b.    
     By defining the inclination angle of the inclined groove  32  and overall shape of the inclined groove  32  in this way, wet performance and snow performance are improved. 
     Specifically, by setting the inclination angle to be greater than 50 degrees and 65 degrees or less in the second range R 2 , snow performance and wet performance are improved as compared with the tire in the related art. 
     As illustrated in  FIG.  2   , preferably, the inclined groove  32  extends to the pattern end PE without intersecting a circumferential main groove which extends in the circumferential direction and goes around the tire circumference, and each block land portion provided between adjacent inclined grooves adjacent in the tire circumferential direction of the inclined grooves  32  disposed in each of half-tread regions on both sides of the tire equator line CL contacts both of the adjacent inclined grooves. 
     The tread pattern  30  does not include the tire circumferential main groove. The tire circumferential main groove includes a linear groove that extends linearly in parallel in the tire circumferential direction and goes around the tire circumference, and a zigzag-shaped groove that extends in the tire circumferential direction and goes around the tire circumference while being displaced in a zigzag-like manner in the tire circumferential direction while the groove cross-section includes a portion that extends in parallel with the tire circumferential direction and goes around the tire circumference. 
     When the tread pattern  30  is provided with such a tire circumferential main groove, the flow of drain toward the pattern end PE of the inclined groove  32  stagnates at the junction of the tire circumferential main groove and the inclined groove  32 , and drainage performance tends to decrease. 
     On the other hand, since each block land portion provided between the adjacent inclined grooves forms a block land portion that contacts both of the adjacent inclined grooves, water pushed by the block land portion when the tire  10  rolls on the wet road surface flows into the inclined groove  32  with good drainage performance, and as a result, wet performance, particularly drainage performance, are improved. 
     Further, as illustrated in  FIG.  2   , preferably, each inclined groove  32  includes a crossing portion  32   c  that crosses between two inclined grooves  32  extending to an outer side in the tire width direction different from the outer side in the tire width direction in which each inclined groove  32  extends, and further the crossing portion  32   c  crosses the tire equator line CL. In this way, water on the road surface pressed into the block land portion of the center region around the tire equator line CL flows reliably into three inclined grooves  32 , and thus drainage performance of the center region where drainage is difficult is improved. 
     As illustrated in  FIG.  2   , the tread pattern  30  preferably includes two connecting grooves  36  and  38  that connect two adjacent inclined grooves adjacent in the tire circumferential direction within the range separated from the tire equator line CL by from 15 to 55% of the periphery distance L in the tire width direction. 
     By providing the connecting grooves  36  and  38 , edge components can be increased, and snow performance can be improved, and also water can flow through the connecting grooves  36  and  38  to the inclined groove  32 , and thus wet performance, particularly drainage performance is improved. The groove widths of the connecting grooves  36  and  38  are narrower than the groove width of the inclined groove  32  at portions where the connecting grooves  36  and  38  connect with the inclined grooves  32 . The groove depths of the connecting grooves  36  and  38  are shallower than the groove depth of the inclined groove  32  (of the connected portions), and the groove depths of the connecting grooves  36  and  38  are, for example, 55% or less of the groove depth of the inclined groove  32  (of the connected portions). 
     The connecting grooves  36  and  38  are preferably grooves that extend toward a side in the tire circumferential direction (the first side) to which the inclined groove  32  extends from the starting end  32   a  to the terminating end  32   b , and toward an inner side in the tire width direction. In this way, an angle of the tip of the land portion formed by the connecting grooves  36  and  38  and the inclined grooves  32  is a large angle (angle close to 90 degrees), and thus the angle of the tip of the land portion is an acute angle, allowing for preventing a local decrease in the rigidity of the land portion. This makes it easy to harden the snow entering the connecting grooves  36  and  38 , and as a result, snow column shear force increases and snow performance is improved. 
     As illustrated in  FIG.  2   , preferably, the connecting groove  38  crosses one of the adjacent inclined grooves, extends to a region of the land portion defined by the one of the adjacent inclined grooves (in  FIG.  2   , the region of the block land portion adjacent to the lower side), and is closed. Since a portion of the connecting groove  38  extends so as to extend in the region of the land portion, edge components increase, and thus snow performance is improved. 
     Of two connecting grooves  36  and  38 , the connecting groove  38  located at the side of the tire equator line CL is referred to as a first connecting groove, and the connecting groove  36  located at an outer side of the first connecting groove in the tire width direction is referred to as a second connecting groove. Hereinafter, since the first connecting groove and the connecting groove  38  are identical, the first connecting groove is also denoted by the reference sign “ 38 ”, and the second connecting groove is also denoted by the reference sign “ 36 ”. The first connecting groove  38  and the second connecting groove  36  are grooves extending linearly. 
     At this time, the crossing portion  32   c , the first connecting groove  38 , and the second connecting groove  36  between the adjacent inclined grooves adjacent in the tire circumferential direction are disposed in this order from the inner side in the tire width direction, and the first connecting groove  38 , the second connecting groove  36 , and the crossing portion  32   c  are inclined to the same side in the tire width direction from the tire circumferential direction. At this time, preferably, an inclination angle θC of the crossing portion  32   c  with respect to the tire circumferential direction is greater than an inclination angle θA of the first connecting groove  38  with respect to the tire circumferential direction, and the inclination angle θA is greater than an inclination angle θB of the second connecting groove  36  with respect to the tire circumferential direction.  FIG.  4 A  is a diagram illustrating inclination angles of the first connecting groove  38 , the second connecting groove  36 , and the crossing portion  32   c . For the inclination angles θA, θB, and θC, reducing the inclination angles toward the outer side in the tire width direction causes edge components extending in the tire width direction to be reduced from the center region toward the outer side in the tire width direction and edge components extending in the tire circumferential direction to be increased from the center region toward the outer side in the tire width direction, allowing lateral force to be increased in the shoulder region and breaking or accelerating force to be increased in the center region on snow-covered road surfaces. 
     In this case, preferably, the inclination angle θB is from 0.6 to 0.8 times the inclination angle θA, and the inclination angle θA is from 0.75 to 0.95 times the inclination angle θC. Accordingly, in addition to snow performance, wet performance, especially drainage performance, can be efficiently improved. 
     Further, as illustrated in  FIG.  2   , the tread pattern  30  includes a shallow connecting groove  40  that connects two adjacent inclined grooves adjacent in the tire circumferential direction within the range separated from the tire equator line CL by greater than 55% and 75% or less of the periphery distance L in the tire width direction. In this case, the shallow connecting groove  40  preferably has a groove depth from 40 to 50% of the groove depths of the adjacent inclined grooves that are at connection positions where the adjacent inclined grooves are connected to the shallow connecting groove  40 . The shallow connecting groove  40  prevents chuck-out in which a rubber portion between two sipes  34  is separated and scattered in the shoulder region during high-speed travel. This improves snow performance during high-speed travel. 
       FIG.  4 B  is a diagram illustrating the block land portion of the tread pattern of the tire according to the embodiment. As illustrated in  FIG.  4 B , the tread pattern  30  includes a first block land portion  42  surrounded by the adjacent inclined grooves, the crossing portion  32   c , and the first connecting groove  38  and a second block land portion  44  surrounded by the adjacent inclined grooves, the first connecting groove  38 , and the second connecting groove  36  between each adjacent inclined grooves adjacent in the tire circumferential direction. In this case, an area S 1  of the first block land portion  42  is preferably smaller than an area S 2  of the second block land portion  44 . Reducing the first block land portion  42  allows proportion of the groove to be increased and edge components to be increased, improving snow performance. Increasing the second block land portion  44  allows a large amount of water to efficiently flow from the second block land portion  44  into the inclined groove  32 , improving wet performance, particularly drainage performance. At this time, to achieve the above effect, the area S 1  is preferably from 75% to 85% of the area S 2 . 
       FIGS.  5 A and  5 B  are diagrams illustrating the shape dimensions of the first block land portion and the second block land portion provided in the tread pattern of the tire according to the embodiment. 
     In the region of the first block land portion  42 , a groove portion of one inclined groove of the inclined grooves  32  at the starting end  32   a  side from the crossing portion  32   c  is provided as a starting groove portion  32   d.    
     When a distance along the tire width direction between the position of a first end  42   a  of the first block land portion  42  located farthest from the starting groove portion  32   d  at the side of the tire equator line CL (inner side in the tire width direction) and a connection position  32   e  where the starting groove portion  32   d  is connected to the inclined groove  32  (one of the adjacent inclined grooves) that contacts the first block land portion  42  (the connection position  32   e  is a center position of the groove width of the starting groove portion  32   d ) is L 1 , and a distance along the tire width direction between the first end  42   a  of the first block land portion  42  and a second end  42   b  of the first block land portion  42  located at the outermost side in the tire width direction is LB 1 , the distance L 1  is preferably from 25% to 35% of the distance LB 1 . 
     At this time, when a distance from the starting end  32   a  of the starting groove portion  32   d  to the connection position  32   e  is L 2 , the distance L 2  is preferably from 40% to 45% of the distance LB 1 . 
     Further, in the region of the second block land portion  44 , a closed groove  45  that extends from one of the adjacent inclined grooves and is closed without being connected to the other of the adjacent inclined grooves is provided. When a distance along the tire width direction between a third end  44   a  of the second block land portion  44  located farthest from the closed groove  45  at the side of the tire equator line CL (inner side in the tire width direction) and a connection position  45   a  where the closed groove  45  is connected to one of the adjacent inclined grooves is L 3 , and a distance along the tire width direction between the third end  44   a  of the second block land portion  44  and a fourth end  44   b  of the second block land portion  44  located at the outermost side in the tire width direction is LB 2 , the distance L 3  is preferably from 25% to 35% of the distance LB 2 . 
     At this time, when a distance from a closed end of the closed groove  45  to the connection position  45   a  is L 4 , the distance L 4  is preferably from 40% to 45% of the distance LB 2 . 
     By setting the distance L 1  and the distance L 3  to from 25% to 35% of the distance LB 1  and the distance LB 2 , the starting groove portion  32   d  and the closed groove  45  that increase edge components can be appropriately disposed in regions of the first block land portion  42  and the second block land portion  44 , and thus a decrease in block rigidity is suppressed and snow performance can be improved. 
     Further, by setting the distance L 2  and the distance L 4  to from 40% to 45% of the distance LB 1  and the distance LB 2 , the starting groove portion  32   d  and the closed groove  45  that increase edge components can be appropriately disposed in the regions of the first block land portion  42  and the second block land portion  44 , and thus a decrease in block rigidity is suppressed and snow performance can be improved. 
     According to the embodiment, when a value obtained by dividing a total length (mm) of lengths projected in the inclination direction A, which is inclined at an angle α (α=0 or more and less than 360 degrees) with respect to the tire width direction, of all grooves provided in the tread pattern  30  by (ground contact width×circumferential length) (mm 2 ) is ρg, a value obtained by dividing a total length (mm) projected in the inclination direction A of all the sipes  34  provided in the tire  10  by (ground contact width×circumferential length) (mm 2 ) is ρs, an average depth (mm) of grooves is Dg, and a snow traction index STI is defined by the following Formula (1), a value of the snow traction index STI at the angle α=30 to 40 degrees is preferably greater than a value of the snow traction index STI at the angle α=0 degrees and is preferably from 104% to 110% of the value of the snow traction index STI at the angle α=0 degrees. 
       STI=−6.8+2202*ρ g+ 672*ρ s+ 7.6* Dg   (1)
 
     By setting the values of the snow traction index STI at the angle α=30 to 40 degrees and at the angle α=0 degrees as described above, snow performance when turning the tire is improved as well as the snow performance when traveling straight. 
     To effectively exhibit snow performance and wet performance of the tire  10  in such a tread pattern  30 , the JIS (Japanese Industrial Standard)—A hardness (JIS-K6253) of an upper layer tread rubber member  18   a  of the tire  10  at 20° C. is preferably set within a range of 50 or more and 70 or less. 
     Since the tire  10  has the tread pattern  30  in which the inclined groove  32  extends from the starting end  32   a  toward the first side in the tire circumferential direction to the terminating end  32   b , the tire  10  is preferably provided with indicator information in which the opposite side of this first side is a tire rotation direction. 
     The indicator information of the rotation direction is displayed by marks or a ridged and grooved portion provided on the sidewall portion of the tire, for example. 
     EXAMPLE, COMPARATIVE EXAMPLE 
     To investigate the effects of the tire  10  of the embodiment, tires having various tread patterns were manufactured and mounted on a vehicle, and a snow performance test and a wet performance test were conducted. The manufactured tires are pneumatic tires with a tire size of 275/45R20. The tires were assembled on rims of rim size (20×9.5 J), and the snow performance test and the wet performance test were conducted under the conditions of an air pressure of 240 kPa and a load of 80% of the maximum load specified by JATMA (The Japan Automobile Tyre Manufacturers Association, Inc.). The vehicle used is a passenger vehicle of 3000 cc Sport Utility Vehicle (SUV). 
     In the snow performance test, the vehicle ran three laps of a handling course on a snow-covered road surface, the lap time for each lap was measured, and an average value of the lap time was obtained. The average value of the lap time was expressed as an index value, with the tire of Comparative Example 1 being assigned as the reference (index value of 100). The tire of Comparative Example 1 has an inclination angle of the inclined groove that has been employed in the related art. 
     In the wet performance test, the vehicle ran three laps of a wet handling course, lap time for each lap was measured, and an average value of the lap time was obtained. The average value of the lap time was expressed as an index value, with the tire of Comparative Example 1 being assigned as the reference (index value of 100). 
     Accordingly, a higher index value means better snow performance and wet performance. 
     In each of Comparative Examples 1 and 2 and Examples 1 to 6, the connecting grooves  36  and  38 , which incline to the inner side in the tire width direction toward the first side in the tire circumferential direction, are provided within a range separated from the tire equator line CL by from 15 to 55% of the periphery distance L in the tire width direction. Further, the distance L 1  and the distance L 3  were set to from 25% to 35% of the distance LB 1  and the distance LB 2 , and the distance L 2  and the distance L 4  were set to from 40% to 45% of the distance LB 1  and the distance LB 2 . 
     Further, by adjusting the arrangement of the sipe  34 , the value of the snow traction index STI at the angle α=30 to 40 degrees was set to from 104% to 110% of the value of the snow traction index STI at the angle α=0 degrees. 
     Table 1 below shows specifications of tread patterns manufactured using the tread pattern  30  illustrated in  FIG.  2    as a reference. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                   
                 Comparative 
                 Comparative 
                 Example 
                 Example 
               
               
                   
                 Example 1 
                 Example 2 
                 1 
                 2 
               
               
                   
               
               
                 Inclination angle of inclined 
                 45 
                 45 
                 45 
                 45 
               
               
                 groove in first range R1 (degrees) 
                   
                   
                   
                   
               
               
                 Inclination angle of inclined 
                 45 
                 45 
                 57 
                 57 
               
               
                 groove in second range R2 (degrees) 
                   
                   
                   
                   
               
               
                 Inclination angle of inclined 
                 85 
                 70 
                 72 
                 72 
               
               
                 groove in third range R3 (degrees) 
                   
                   
                   
                   
               
               
                 Inclination angles of inclined 
                 85 
                 85 
                 85 
                 85 
               
               
                 groove in fourth range R4 (degrees) 
                   
                   
                   
                   
               
               
                 Circumferential-direction distance 
                 50 
                 62 
                 68 
                 68 
               
               
                 Y/width-direction distance X (%) 
                   
                   
                   
                   
               
               
                 Presence of shallow connecting 
                 No 
                 No 
                 No 
                 Yes 
               
               
                 groove 40 
                   
                   
                   
                   
               
               
                 Angle of θ A , θ B , θ C  (degrees) 
                 θ A  = 28 
                 θ A  = 28 
                 θ A  = 32 
                 θ A  = 32 
               
               
                   
                 θ B  = 15 
                 θ B  = 15 
                 θ B  = 25 
                 θ B  = 25 
               
               
                   
                 θ C  = 40 
                 θ C  = 40 
                 θ C  = 35 
                 θ C  = 35 
               
               
                 Area S 1 /area S 2 (%) 
                 68 
                 69 
                 71 
                 72 
               
               
                 Snow performance 
                 100 
                 101 
                 102 
                 104 
               
               
                 Wet performance 
                 100 
                 99 
                 101 
                 101 
               
               
                   
               
               
                   
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
               
                 Inclination angle of inclined groove in 
                 45 
                 45 
                 45 
                 45 
               
               
                 first range R1 (degrees) 
                   
                   
                   
                   
               
               
                 Inclination angle of inclined groove in 
                 57 
                 57 
                 57 
                 57 
               
               
                 second range R2 (degrees) 
                   
                   
                   
                   
               
               
                 Inclination angle of inclined groove in 
                 72 
                 72 
                 72 
                 72 
               
               
                 third range R3 (degrees) 
                   
                   
                   
                   
               
               
                 Inclination angles of inclined groove 
                 85 
                 85 
                 85 
                 85 
               
               
                 in fourth range R4 (degrees) 
                   
                   
                   
                   
               
               
                 Circumferential-direction distance Y/ 
                 68 
                 68 
                 68 
                 68 
               
               
                 width-direction distance X (%) 
                   
                   
                   
                   
               
               
                 Presence of shallow connecting 
                 Yes 
                 Yes 
                 Yes 
                 Yes 
               
               
                 groove 40 
                   
                   
                   
                   
               
               
                 Angle of θ A , θ B , θ C  (degrees) 
                 θ A  = 32 
                 θ A  = 32 
                 θ A  = 32 
                 θ A  = 32 
               
               
                   
                 θ B  = 25 
                 θ B  = 25 
                 θ B  = 25 
                 θ B  = 25 
               
               
                   
                 θ C  = 35 
                 θ C  = 35 
                 θ C  = 35 
                 θ C  = 35 
               
               
                 Area S 1 /area S 2 (%) 
                 73 
                 75 
                 85 
                 88 
               
               
                 Snow performance 
                 105 
                 107 
                 106 
                 104 
               
               
                 Wet performance 
                 103 
                 105 
                 105 
                 103 
               
               
                   
               
            
           
         
       
     
     According to Table 1 described above, by setting the inclination angle of the inclined groove in the first to fourth ranges R 1  to R 4  and the circumferential-direction distance Y/width-direction distance X in the above-mentioned numerical range, snow performance and wet performance are improved. It can be seen that the snow performance is improved by providing the shallow connecting groove  40 . It can be seen that the snow performance and wet performance are improved by setting the area S 1 /area S 2  to be from 75% to 85%. 
     Although the tire of the present technology has been described in detail above, the present technology is not limited to the embodiments and examples, and various improvements and changes may naturally be made without departing from the gist of the present technology.