JP6156001B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that improves steering stability at high speed running and durability at high speed running with a camber.

  Conventionally, for example, in Patent Document 1, at least one carcass and belt layer, and a belt cover layer in which a reinforcing cord made of an organic fiber cord is spirally wound around the tire radial direction outside the belt layer in the tire radial direction. And a tread portion having a tread surface having a different tread surface ratio across the tire equatorial plane, wherein the tread surface has a tire diameter on a side having a smaller groove area ratio across the tire equatorial plane in the meridional section. A pneumatic tire having a tread profile in which the outermost position in the direction is arranged and the amount of depression of the tread profile from the outermost position in the tire radial direction to the tire radial direction at each outermost end in the tire width direction is equally described. Has been.

  The pneumatic tire described in Patent Document 1 includes a tread portion having a tread surface having a different groove area ratio across the tire equator plane, so that drainage is performed on the side having a larger groove area ratio (that is, the side having more grooves). Performance can be obtained, and steering stability on a dry road surface can be obtained on the side having a small groove area ratio (that is, a side having few grooves and high rigidity), so that both drainage performance and steering stability can be achieved. Moreover, according to this pneumatic tire, the tread surface has a tread profile in which the outermost position in the tire radial direction is arranged on the side where the groove area ratio is small across the tire equatorial plane in the meridional section, that is, on the side where the rigidity of the tread portion is high. Since the contact pressure is increased on the high-rigidity side to make the contact pressure uniform throughout the contact area, the rigidity of the tread part that sandwiches the tire equator surface without deteriorating durability at high speeds The deterioration of conicity caused by the difference can be suppressed.

JP 2011-230699 A

  By the way, in recent years, with the improvement in performance of vehicles, there is a demand for achieving both handling stability at high speed running and durability at high speed running with a camber. Here, in order to ensure steering stability, it is effective to project the rib contour outward in the tire radial direction from the tread surface contour so as to improve the ground contact property of the rib formed in the tread portion. On the other hand, in the case of application to a vehicle with a camber, since the contact length becomes longer on the inner rib than the outer rib on the tire equator when the vehicle is mounted, durability at high speed tends to decrease. . For this reason, it is difficult to achieve both steering stability at high speed and durability at high speed with camber.

  The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire that can achieve both steering stability at high speed running and durability at high speed running with a camber.

  In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention is a tire width direction in which the tire equatorial plane is a ridge by a plurality of main grooves extending along the tire circumferential direction on the tread surface. In a pneumatic tire in which at least two ribs are formed on both sides and the direction inside and outside the vehicle is specified when the vehicle is mounted, the rib in the region outside the vehicle from the tire equator plane has an outline of the tread surface The rib protrudes outward in the tire radial direction from the line, and the protruding amount of each rib is increased from the tire equatorial plane toward the outer side in the tire width direction, and the rib in the region inside the vehicle from the tire equatorial plane is The center of the radius of curvature of the dent line is located on the outer side in the tire radial direction with respect to the tread surface, and from the outer side in the tire width direction. Wherein the recess of each said rib toward ya equatorial plane is smaller.

  According to this pneumatic tire, on the vehicle outer side, by projecting the rib to the outer side in the tire radial direction from the contour line, the grounding property of the rib is improved, so that the steering stability during high speed traveling can be improved. . In addition, because the ribs are recessed inward in the tire radial direction from the contour line on the inner side of the vehicle, excessive grounding of the ribs is alleviated, so that the ground contact length is uniform between the ribs and durability at high speed running with a camber Can be improved. As a result, it is possible to achieve both handling stability at high speed and durability at high speed with camber. In addition, since the protruding amount of each rib is greatly increased from the tire equatorial plane toward the outer side in the tire width direction on the vehicle outer side, the ground contact property of each rib is uniformed, so that steering stability during high-speed driving is achieved. The effect of improving is remarkably obtained. In addition, the amount of dents on each rib on the inner side of the vehicle is reduced from the outer side in the tire width direction toward the tire equatorial plane. The effect of improving the durability is significantly obtained. Therefore, it is possible to achieve both a high level of driving stability at high speeds and durability at high speeds with camber at a high level.

  Further, in the pneumatic tire according to the present invention, the center rib on the vehicle outer side which is disposed on the tire equator plane and has an area of 50% or more of the rib width on the vehicle outer side from the tire equator plane is more tire than the contour line. It is characterized by projecting radially outward.

  According to this pneumatic tire, since the ground contact property is further improved by projecting the center rib, the effect of improving the steering stability during high speed traveling can be obtained more remarkably.

  In the pneumatic tire of the present invention, the rib protruding outward in the tire radial direction from the contour line has a protrusion amount of 0.7% or more and 2.0% or less of the rib width, and is more than the contour line. The ribs recessed inward in the tire radial direction have a recess amount of 0.7% to 2.5% of the rib width.

  According to this pneumatic tire, the protruding amount of the rib is 0.7% or more and 2.0% or less of the rib width, and the recessed amount of the rib is 0.7% or more and 2.5% of the rib width. By setting it as the following, it can maintain to high altitude without impairing both performance of steering stability in high-speed driving, and durability in high-speed driving with a camber.

  In the pneumatic tire of the present invention, the rib protruding outward in the tire radial direction from the contour line has a protrusion amount of 0.7% or more and 2.0% or less of the rib width, and is more than the contour line. The ribs recessed inward in the tire radial direction have a recess amount of not less than 0.7% and not more than 2.5% of the rib width, and are disposed on the tire equatorial plane so that the rib width extends from the tire equatorial plane to the vehicle outer side. The center rib on the vehicle outer side having a region of 50% or more is formed to protrude outward in the tire radial direction from the contour line, and the protruding amount is 0.7% or more and 2.5% or less of the rib width. Features.

  According to this pneumatic tire, since the ground contact property is further improved by projecting the center rib, the effect of improving the steering stability during high speed traveling can be obtained more remarkably. The rib protrusion amount is 0.7% to 2.0% of the rib width, and the rib recess amount is 0.7% to 2.5% of the rib width. By setting the protruding amount to 0.7% or more and 2.5% or less of the rib width, it is more advanced without impairing both the handling stability at high speed and the durability at high speed with camber. Can be maintained.

  The pneumatic tire according to the present invention can achieve both steering stability at high speed and durability at high speed with camber.

FIG. 1 is a meridional sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a meridional sectional view of a tread portion of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 3 is a meridional sectional view of a tread portion of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 4 is a meridional sectional view of a tread portion of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 5 is a meridional sectional view of a tread portion of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 6 is a meridional sectional view of a tread portion of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 7 is an enlarged meridian cross-sectional view of the tread portion of the pneumatic tire according to the embodiment of the present invention. FIG. 8 is a meridional cross-sectional enlarged view of the tread portion of the pneumatic tire according to the embodiment of the present invention. FIG. 9 is an enlarged meridian cross-sectional view of the tread portion of the pneumatic tire according to the embodiment of the present invention. FIG. 10 is an enlarged meridian cross-sectional view of the tread portion of the pneumatic tire according to the embodiment of the present invention. FIG. 11 is an enlarged meridian cross-sectional view of the tread portion of the pneumatic tire according to the embodiment of the present invention. FIG. 12 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. FIG. 13 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

  1 is a meridional sectional view of a pneumatic tire according to the present embodiment, and FIGS. 2 to 6 are meridional sectional views of tread portions of other examples of the pneumatic tire according to the present embodiment. FIG. 11 is an enlarged meridian cross-sectional view of the tread portion of the pneumatic tire according to the present embodiment.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line.

  As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both sides thereof, and a sidewall portion 4 and a bead portion 5 that are sequentially continuous from the shoulder portions 3. Yes. The pneumatic tire 1 includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

  The tread portion 2 is made of a rubber material (tread rubber), is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread surface 21 extends in the tire circumferential direction and has at least three straight main grooves parallel to the tire equator line CL (three in FIG. 1, four in FIG. 2, and five in FIG. 3). The main groove 22 is provided. The tread surface 21 extends along the tire circumferential direction by the plurality of main grooves 22 and has at least four ribs 23 (four in FIG. 1 and five in FIG. 2) parallel to the tire equator line CL. (In FIG. 3, the number is 6). Although not clearly shown in the drawing, the tread surface 21 is provided with a lug groove that is formed with a groove depth shallower than the main groove 22 and intersects the main groove 22 in each rib 23. The rib 23 is divided into a plurality in the tire circumferential direction by lug grooves. Further, the lug groove is formed to open to the outer side in the tire width direction on the outermost side in the tire width direction of the tread portion 2. Note that the lug groove may have either a form communicating with the main groove 22 or a form not communicating with the main groove 22.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. Further, the sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire 1. The bead unit 5 includes a bead core 51 and a bead filler 52. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 52 is a rubber material disposed in a space formed by folding the end portion in the tire width direction of the carcass layer 6 at the position of the bead core 51.

  The carcass layer 6 is configured such that each tire width direction end portion is folded back from the tire width direction inner side to the tire width direction outer side by a pair of bead cores 51 and is wound around in a toroidal shape in the tire circumferential direction. It is. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged in parallel at an angle in the tire circumferential direction with an angle with respect to the tire circumferential direction being along the tire meridian direction. The carcass cord is made of organic fibers (polyester, rayon, nylon, etc.). The carcass layer 6 is provided as at least one layer.

  The belt layer 7 has a multilayer structure in which at least two belts 71 and 72 are laminated, and is disposed on the outer side in the tire radial direction which is the outer periphery of the carcass layer 6 in the tread portion 2 and covers the carcass layer 6 in the tire circumferential direction. It is. The belts 71 and 72 are made by coating a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20 degrees to 30 degrees) with a coat rubber with respect to the tire circumferential direction. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). Further, the overlapping belts 71 and 72 are arranged so that the cords intersect each other.

  The belt reinforcing layer 8 is disposed on the outer side in the tire radial direction which is the outer periphery of the belt layer 7 and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is formed by coating a plurality of cords (not shown) arranged substantially parallel (± 5 degrees) in the tire circumferential direction and in the tire width direction with a coat rubber. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). The belt reinforcing layer 8 shown in FIG. 1 is disposed so as to cover the end of the belt layer 7 in the tire width direction. The configuration of the belt reinforcing layer 8 is not limited to the above, and is not clearly shown in the figure. However, the belt reinforcing layer 8 is configured to cover the entire belt layer 7 or has two reinforcing layers, for example, on the inner side in the tire radial direction. The reinforcing layer is formed so as to be larger in the tire width direction than the belt layer 7 and is disposed so as to cover the entire belt layer 7, and the reinforcing layer on the outer side in the tire radial direction is disposed so as to cover only the end portion in the tire width direction of the belt layer 7. Alternatively, for example, a configuration in which two reinforcing layers are provided and each reinforcing layer is disposed so as to cover only the end portion in the tire width direction of the belt layer 7 may be employed. That is, the belt reinforcing layer 8 overlaps at least the end portion in the tire width direction of the belt layer 7. The belt reinforcing layer 8 is provided by winding a strip-shaped strip material (for example, a width of 10 [mm]) in the tire circumferential direction.

  In the pneumatic tire 1 of the present embodiment, the direction inside and outside the vehicle is specified when the vehicle is mounted. In the tread portion 2, the inner side of the vehicle is referred to as the vehicle inner side and the outer side of the vehicle is referred to as the outer side of the vehicle with reference to the tire equatorial plane CL. The designation of the direction with respect to the vehicle inner side and the vehicle outer side is not clearly shown in the drawing, but is indicated by, for example, an index provided on the sidewall portion 4. In addition, designation | designated of a vehicle inner side and a vehicle outer side is not restricted to the case where it mounts | wears with a vehicle. For example, when the rim is assembled, the direction of the rim with respect to the inside and outside of the vehicle is determined in the tire width direction. For this reason, when the pneumatic tire 1 is assembled with a rim, the orientation with respect to the vehicle inner side and the vehicle outer side is designated in the tire width direction.

  In addition, by designating the inside / outside direction of the vehicle when the vehicle is mounted, the rib 23 of the tread portion 2 described above is located in a region outside the vehicle from the tire equatorial plane CL as shown in FIGS. Let it be rib 23out, and let it be rib 23in in the area inside the vehicle. More specifically, as shown in FIGS. 1 to 6, a rib 23out on the vehicle outer side than the main groove 22 on the outermost side of the vehicle is a vehicle outer shoulder rib 23out-sh, and the inner groove 22 on the vehicle inner side of the main groove 22 on the innermost side of the vehicle. The rib 23in is referred to as a vehicle inner shoulder rib 23in-sh. Further, as shown in FIGS. 2 and 6, the rib 23 arranged on the tire equatorial plane CL is defined as a center rib 23ce. The center rib 23ce shown in FIGS. 2 and 6 has a center in the tire width direction of the rib width on the tire equatorial plane CL, that is, a region of 50% of the rib width from the tire equatorial plane CL to the vehicle outer side and the vehicle inner side. is there. Further, as shown in FIG. 4, in the center rib 23ce arranged on the tire equatorial plane CL, the center of the tire width direction of the rib width is not arranged on the tire equatorial plane CL, and the rib width on the outer side of the vehicle is not arranged. The rib 23 having a region of 50% or more is referred to as a center rib 23ce outside the vehicle, and is included in the rib 23out in the region outside the vehicle. Further, although not shown in the drawing, in the center rib 23ce arranged on the tire equatorial plane CL, the center of the rib width in the tire width direction is not arranged on the tire equatorial plane CL, and the rib is formed in the region inside the vehicle. The ribs 23 arranged to exceed 50% of the width are referred to as center ribs 23ce inside the vehicle. Further, as shown in FIGS. 1, 3, and 5, the main groove 22 disposed on the tire equatorial plane CL is defined as a center main groove 22ce.

  In such a pneumatic tire 1, at least two ribs 23 are formed on both sides in the tire width direction with the tire equatorial plane CL as a ridge by a plurality of main grooves 22 extending along the tire circumferential direction on the tread surface 21. Has been. 7 to 9, when new, the ribs 23out and 23out-sh in the region outside the vehicle from the tire equatorial plane CL protrude outward in the tire radial direction from the contour line L of the tread surface 21. Further, the protruding amounts (maximum protruding amount: maximum distance between the contour line L and the protruding portion) G1, G2 of the ribs 23out, 23out-sh from the tire equatorial plane CL toward the outer side in the tire width direction are formed large. Further, the ribs 23in and 23in-sh in the vehicle inner side area than the tire equatorial plane CL are recessed inward in the tire radial direction from the contour line L, and the center S of the radius of curvature of the recessed line is more than that of the tread surface 21. Depression amount of each rib 23in, 23in-sh (maximum dent amount: maximum distance between contour line L and dent portion) D1, D2 located on the outer side in the tire radial direction and from the outer side in the tire width direction toward the tire equatorial plane CL Is formed small.

  Here, the contour line L is adjacent to both sides of the ribs 23out and 23in in the tire width direction in the meridional section in the case of the ribs 23out and the ribs 23in disposed between the main grooves 22 as shown in FIG. An arc that passes through at least three of the four open ends P in the two main grooves 22 and can be drawn with the maximum curvature radius with the center on the inner side in the tire radial direction of the tread surface 21. The rib widths Wout and Win of the ribs 23out and 23in are distances in the tire width direction between the two opening ends P near the ribs 23out and 23in in the two main grooves 22 adjacent to both sides of the ribs 23out and 23in. .

  Further, as shown in FIG. 8, in the case of the shoulder rib 23out-sh, the contour line L has a grounding end T at the shoulder rib 23out-sh in the meridional section, and the grounding end T is defined as P1. When the opening end of the outer main groove 22 closer to the vehicle outer side is P2 and the opening end of the outermost main groove 22 closer to the vehicle inner side is P3, the tire diameter of the tread surface 21 passes through P1, P2, P3. An arc with a radius of curvature centered in the direction. The rib width Wout-sh of the shoulder rib 23out-sh is a distance in the tire width direction between the ground contact end T (P1) and the opening end P2.

  Further, as shown in FIG. 9, in the case of the shoulder rib 23in-sh, the contour line L has a grounding end T on the shoulder rib 23in-sh in the meridional section as in the case of the shoulder rib 23out-sh. When the grounding end T is P1, the opening end of the innermost main groove 22 on the inner side of the vehicle is P2, and the opening end of the innermost main groove 22 on the outer side of the vehicle is P3, P1, P2 , P3, and an arc of curvature radius having a center on the inner side in the tire radial direction of the tread surface 21. The rib width Win-sh of the shoulder rib 23in-sh is a distance in the tire width direction between the ground contact end T (P1) and the opening end P2.

  In addition, as shown in FIG. 10 (in FIG. 10, rib 23out is shown), when chamfering C is given to the opening end of the main groove 22, the end point located on the outermost side in the tire radial direction is defined as the opening end. A line L is defined.

  Further, the ground contact end T means that when the pneumatic tire 1 is assembled to a regular rim and filled with a regular internal pressure and a regular load is applied, the tread surface 21 of the tread portion 2 of the pneumatic tire 1 is a road surface. In the contact area, both outermost ends in the tire width direction are continuous in the tire circumferential direction.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load is “maximum load capacity” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

  Thus, in the pneumatic tire 1 of the present embodiment, the ribs 23out and 23out-sh in the region outside the vehicle from the tire equatorial plane CL protrude outward in the tire radial direction from the contour line L of the tread surface 21; The protruding amounts G1 and G2 of the ribs 23out and 23out-sh are gradually increased from the tire equatorial plane CL toward the outer side in the tire width direction, and the ribs 23in and 23in− in the region on the vehicle inner side than the tire equatorial plane CL are formed. sh is recessed inward in the tire radial direction from the contour line L, the center S of the radius of curvature of the line of the recess is located on the outer side in the tire radial direction from the tread surface 21, and the tire equatorial plane CL from the outer side in the tire width direction. The recesses D1 and D2 of the ribs 23in and 23in-sh are gradually reduced toward the bottom.

  According to the pneumatic tire 1, the ribs 23out and 23out-sh are protruded outward in the tire radial direction from the contour line L on the outer side of the vehicle, so that the ground contact property of the ribs 23out and 23out-sh is improved. It is possible to improve the handling stability during traveling. Moreover, on the vehicle inner side, the ribs 23in and 23in-sh are recessed inward in the tire radial direction from the contour line L so that the center S of the radius of curvature of the recessed line is positioned on the outer side in the tire radial direction from the tread surface 21. As a result, excessive contact between the ribs 23in and 23in-sh is alleviated, so that the contact length between the ribs 23 (the length in the tire circumferential direction in the region where the tread surface 21 contacts the road surface) is made uniform, and the camber It becomes possible to improve durability at high speed running. As a result, it is possible to achieve both steering stability at high speed running and durability at high speed running with a camber. Moreover, on the vehicle outer side, the protruding amounts G1 and G2 of the ribs 23out and 23out-sh are formed so as to increase from the tire equatorial plane CL toward the outer side in the tire width direction, whereby the grounding of the ribs 23out and 23out-sh is achieved. As a result, the effect of improving the steering stability during high-speed traveling is remarkably obtained. Further, on the vehicle inner side, the recesses D1 and D2 of the ribs 23in and 23in-sh are formed to be small from the outer side in the tire width direction toward the tire equatorial plane CL, so that the ribs 23in and 23in-sh are excessive. Since the ground contact is uniformly relieved, the effect of improving the durability at a high speed traveling with a camber is remarkably obtained. Therefore, it is possible to achieve both a high level of driving stability at high speeds and durability at high speeds with camber at a high level.

  Further, in the pneumatic tire 1 of the present embodiment, in the above configuration, as shown in FIGS. 2, 4, and 11, the pneumatic tire 1 is disposed on the tire equatorial plane CL and has a rib width Wce from the tire equatorial plane CL to the vehicle outer side. It is preferable that the center rib 23ce outside the vehicle having a region of 50% or more is formed so as to protrude outward in the tire radial direction from the contour line L.

  Here, as shown in FIG. 11, the contour line L is the two main grooves adjacent to both sides in the tire width direction of the center rib 23ce in the meridional section with respect to the center rib 23ce disposed between the main grooves 22. 22 is an arc that passes through at least three of the four open ends P at 22 and can be drawn with a maximum radius of curvature with the center in the tire radial direction of the tread surface 21. Also here, on the vehicle outer side, the protruding amounts G3, G1, G2 of the ribs 23ce, 23out, 23out-sh are formed larger from the tire equatorial plane CL toward the outer side in the tire width direction.

  According to this pneumatic tire 1, since the ground contact property is further improved by projecting the center rib 23ce, the effect of improving the steering stability during high speed traveling can be obtained more remarkably. Note that there is a region that is arranged on the tire equator plane CL and that is less than 50% of the rib width Wce from the tire equator plane CL to the vehicle outer side (there is a region that exceeds 50% of the rib width Wce on the vehicle inner side). The ribs 23ce are preferably formed along the contour line L without protrusions or dents in order to obtain the effect of improving the steering stability during high-speed traveling.

  Further, in the pneumatic tire 1 of the present embodiment, the ribs 23out and 23out-sh that protrude outward in the tire radial direction from the contour line L have the protruding amounts G1 and G2 of 0.7% of the rib widths Wout and Wout-sh. The ribs 23in and 23in-sh which are 20% or more and 2.0% or less and are recessed inward in the tire radial direction from the contour line L have dents D1 and D2 of 0.7% or more and 2.5% of the rib widths Win and Win-sh % Or less is preferable.

  According to this pneumatic tire 1, the protrusion amounts G1, G2 of the ribs 23out, 23out-sh are 0.7% to 2.0% of the rib widths Wout, Wout-sh, and the ribs 23in, 23in- By setting the dents D1 and D2 of sh to be 0.7% to 2.5% of the rib widths Win and Win-sh, the handling stability at high speed and the durability at high speed with camber High performance can be maintained without impairing both performances.

  Further, in the pneumatic tire 1 of the present embodiment, the ribs 23out and 23out-sh that protrude outward in the tire radial direction from the contour line L have the protruding amounts G1 and G2 of 0.7% of the rib widths Wout and Wout-sh. The ribs 23in and 23in-sh which are 20% or more and 2.0% or less and are recessed inward in the tire radial direction from the contour line L have dents D1 and D2 of 0.7% or more and 2.5% of the rib widths Win and Win-sh %, And the center rib 23ce on the vehicle outer side having an area of 50% or more of the rib width Wce on the outer side of the vehicle from the tire equatorial plane CL is more in the tire radial direction than the contour line L. It is preferable that the protrusion protrudes outward, and the protrusion amount G3 is 0.7% or more and 2.5% or less of the rib width Wce.

  According to this pneumatic tire 1, since the ground contact property is further improved by projecting the center rib 23ce, the effect of improving the steering stability during high speed traveling can be obtained more remarkably. The protrusion amounts G1 and G2 of the ribs 23out and 23out-sh are 0.7% to 2.0% of the rib widths Wout and Wout-sh, and the recesses D1 and D2 of the ribs 23in and 23in-sh. Is set to 0.7% to 2.5% of the rib widths Win and Win-sh, and the protruding amount G3 of the center rib 23ce is set to 0.7% to 2.5% of the rib width Wce. Thus, it is possible to maintain a higher level without impairing both the stability of driving at high speed and the durability at high speed with camber.

  12 and 13 are charts showing the results of the performance test of the pneumatic tire according to this example. In this example, performance tests on high speed maneuverability (steering stability during high speed driving) and high speed durability with camber (durability during high speed driving with camber) are performed for multiple types of pneumatic tires with different conditions. It was broken.

  In this test, a pneumatic tire having a tire size of 295 / 35R21 was used as a test tire.

  The method for evaluating high-speed safety is to assemble the test tire on a rim of 21 x 10 J, fill it with air pressure of 260 kPa, mount it on a test vehicle (passenger vehicle with a displacement of 4800 cc), and run on a dry road test course. The steering performance at the time of lane change and cornering and the stability at the time of going straight are performed by sensory evaluation by one skilled test driver. This sensory evaluation is indicated by an index based on a conventional pneumatic tire as a reference (100), and the higher this index is, the better the steering stability is.

  The high-speed durability evaluation method with camber is as follows: The test tire is assembled on a rim of 21 × 10 J, filled with air pressure of 340 kPa, a load of 7.65 kN is applied, the camber angle is −2.7 degrees, and the drum durability test is performed. The machine was run at the following speed step, and the speed when the test machine detected a tire failure was measured. Then, using the conventional pneumatic tire as a reference, it was evaluated how many steps were improved or how many steps were reduced. Here, +1 step indicates that the vehicle can travel for 20 minutes at +10 km / h, and +0.5 step indicates that the vehicle can travel for 10 minutes at +10 km / h.

・ Step0 ... Running time 0min ... Speed 0km / h
・ Step1 ... Running time 1min ... Speed 0-190km / h
・ Step2 ... Running time 5min ... Speed 190km / h
・ Step3 ... Running time 5min ... Speed 240km / h
・ Step4 ... Running time 10min ... Speed 250km / h
・ Step5: Travel time 10min ... Speed 260km / h
Step 6: Traveling time 10 min ... Speed 270 km / h
Step 7: Traveling time 20 min ... Speed 280 km / h
・ Step8 ... Running time 20min ... Speed 290km / h
・ Step9 ... Running time 20min ... Speed 300km / h
・ Step 10: Traveling time 20 min ... Speed 310 km / h
Thereafter, the speed is increased by +1 step (+10 km / h, 20 min running) until failure.

  FIG. 12 shows the rib structure of FIG. In FIG. 12, in the pneumatic tire of Conventional Example 1, each rib does not protrude and is not recessed. In the pneumatic tire of Comparative Example 1, the outer ribs of the vehicle protrude, but the other ribs do not protrude and are not recessed. In the pneumatic tire of Comparative Example 2, the vehicle inner rib is recessed, but the other ribs do not protrude and are not recessed. In the pneumatic tire of Comparative Example 3, the vehicle outer rib and the vehicle inner rib protrude. In the pneumatic tire of Comparative Example 4, the vehicle inner rib and the vehicle outer rib are recessed.

  On the other hand, in FIG. 12, in the pneumatic tires of Examples 1 to 9, the vehicle outer rib protrudes, and the protruding amount of each rib is increased from the tire equatorial plane toward the outer side in the tire width direction, and the vehicle inner rib. Is recessed, and the amount of recess of each rib is formed smaller from the outer side in the tire width direction toward the tire equatorial plane. In the pneumatic tires of Examples 4 to 9, the protruding amount of the ribs and the recessed amount of the ribs are within the specified ranges.

  FIG. 13 shows the rib structure of FIG. In FIG. 13, in the pneumatic tire of Conventional Example 2, each rib does not protrude and is not recessed. In the pneumatic tire of Comparative Example 5, the vehicle outer rib protrudes, but the other ribs including the center rib do not protrude and are not recessed. In the pneumatic tire of Comparative Example 6, the vehicle inner rib is recessed, but other ribs including the center rib do not protrude and are not recessed. In the pneumatic tire of Comparative Example 7, the vehicle outer rib and the vehicle inner rib protrude except for the center rib. In the pneumatic tire of Comparative Example 8, the vehicle outer rib and the vehicle inner rib are recessed except for the center rib.

  On the other hand, in FIG. 13, the pneumatic tires of Examples 10 to 22 have the vehicle outer rib protruding and the vehicle inner rib recessed. In the pneumatic tires of Examples 10 to 11 and Examples 19 to 22, the center rib protrudes further. In the pneumatic tires of Examples 15 to 22, the protruding amount of the ribs and the recessed amount of the ribs are within the specified ranges.

  And as shown to the test result of FIG. 12 and FIG. 13, it turns out that the high-speed stability and the high-speed durability with a camber are improved in the pneumatic tire of Example 1- Example 22.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 21 Tread surface 22 Main groove 22ce Center main groove 23 Rib 23out Vehicle outer side rib 23out-sh Vehicle outer side shoulder rib 23in Vehicle inner side rib 23in-sh Vehicle inner side shoulder rib 23ce Center rib CL tire Equatorial plane L Contour line P, P2, P3 Open end of main groove S Center of radius of curvature T (P1) Grounding end

Claims (4)

A plurality of main grooves extending along the tire circumferential direction on the tread surface form at least two ribs on both sides in the tire width direction with the tire equator surface as a ridge, and the direction inside and outside the vehicle when the vehicle is mounted is In the specified pneumatic tire,
The ribs in the region outside the vehicle from the tire equator plane protrude outward in the tire radial direction from the outline of the tread surface, and the protruding amount of each rib from the tire equator plane toward the outer side in the tire width direction Is formed large,
The rib in the region on the vehicle inner side than the tire equator plane is recessed inward in the tire radial direction with respect to the contour line, and the center of the radius of curvature of the concave line is located on the outer side in the tire radial direction with respect to the tread surface. A pneumatic tire is characterized in that a dent amount of each rib is formed smaller from the outer side in the tire width direction toward the tire equatorial plane.   A center rib on the vehicle outer side, which is disposed on the tire equator plane and has an area of 50% or more of the rib width on the vehicle outer side from the tire equator plane, is formed to protrude outward in the tire radial direction from the contour line. The pneumatic tire according to claim 1.   The rib protruding outward in the tire radial direction from the contour line has a protruding amount of 0.7% or more and 2.0% or less of the rib width, and the rib recessed inward in the tire radial direction from the contour line is The pneumatic tire according to claim 1 or 2, wherein a dent amount is 0.7% or more and 2.5% or less of a rib width.   The rib protruding outward in the tire radial direction from the contour line has a protruding amount of 0.7% or more and 2.0% or less of the rib width, and the rib recessed inward in the tire radial direction from the contour line is The dent amount is 0.7% or more and 2.5% or less of the rib width, and is disposed on the tire equator plane and has an area of 50% or more of the rib width on the vehicle outer side from the tire equator plane. The center rib is formed to protrude outward in the tire radial direction from the contour line, and the protruding amount is 0.7% or more and 2.5% or less of the rib width. Pneumatic tires.

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