JP2013177114A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of making both compatible in dry performance and wet performance of the tire.SOLUTION: In a pneumatic tire 1, a circumferential directional thin groove 24 is arranged in a position partitioning an outside second land part 34 and an outside shoulder land part 35. A center land part 33 is a rib of continuing in the tire circumferential direction, and an inside second land part 32 and the outside second land part 34 are block rows divided in the tire circumferential direction by a plurality of lug grooves 321 and 341. The groove area ratio S2 of the center land part 33, the groove area ratio S1 of the inside second land part 32 and the groove area ratio S3 of the outside second land part 34, have the relationship of S2<S3<S1. A groove width Wd of the circumferential directional thin groove 24 and a maximum valve Wmax of groove widths of the other three circumferential directional main grooves 21-23, have the relationship of 3.1≤Wmax/Wd≤5.0.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can achieve both dry performance and wet performance of a tire.

  Conventionally, it is divided into three circumferential main grooves, one circumferential narrow groove having a narrower width than these circumferential main grooves, and these circumferential main grooves and circumferential narrow grooves. A pneumatic tire provided with five rows of land portions in a tread portion is known (for example, see FIG. 10). In such a configuration, when the pneumatic tire is mounted on the vehicle with the circumferential narrow groove side on the outer side in the vehicle width direction, the rigidity of the outer region in the vehicle width direction of the tire is secured, and the dry performance of the tire is improved. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

JP 2010-215221 A

  By the way, in recent high-performance sports summer tires, there is a problem that requires both dry performance and wet performance of the tire.

  Therefore, the present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire that can achieve both dry performance and wet performance of a tire.

  In order to achieve the above object, a pneumatic tire according to the present invention includes three circumferential main grooves, one circumferential narrow groove having a narrower groove width than the circumferential main groove, and the circumferential main groove. A pneumatic tire comprising a tread portion including a row of center land portions, a pair of left and right second land portions, and a pair of left and right shoulder land portions, which are partitioned into a groove and the circumferential narrow groove, wherein the center land portion is The second land portion and the shoulder land portion in one area serving as a boundary are referred to as an inner second land portion and an inner shoulder land portion, and the second land portion and the shoulder land portion in the other region are referred to as an outer second land portion and When referred to as an outer shoulder land portion, the circumferential narrow groove is disposed at a position that divides the outer second land portion and the outer shoulder land portion, and the center land portion has a tire circumference. The inner second land portion and the outer second land portion are block rows divided in the tire circumferential direction by a plurality of lug grooves, the groove area ratio S2 of the center land portion, The groove area ratio S1 of the inner second land portion and the groove area ratio S3 of the outer second land portion have a relationship of S2 <S3 <S1, and the groove width Wd of the circumferential narrow groove and the other The maximum value Wmax of the groove widths of the three circumferential main grooves has a relationship of 3.1 ≦ Wmax / Wd ≦ 5.0.

  In the pneumatic tire according to the present invention, (1) the groove area ratio S2 of the center land portion, the groove area ratio S1 of the inner second land portion, and the groove area ratio S3 of the outer second land portion are S2 <S3 <S1. Therefore, the rigidity of the center land portion and the rigidity of the outer second land portion are enhanced, and the drainage performance of the region having the inner second land portion is improved. Further, (2) in the configuration having the groove area ratios S1 to S3, the groove width Wd of the circumferential narrow groove and the maximum value Wmax of the groove widths of the other three circumferential main grooves are 3.1. By having the relationship of ≦ Wmax / Wd ≦ 5.0, the rigidity of the region having the circumferential narrow groove is increased. As a result, there is an advantage that the dry performance and the wet performance of the tire are compatible when the tire is mounted on the vehicle with the region on the circumferential narrow groove side outside in the vehicle width direction.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a plan view showing a tread surface of the pneumatic tire depicted in FIG. 1. FIG. 3 is an explanatory diagram showing an inner second land portion and a center land portion of the pneumatic tire depicted in FIG. 1. FIG. 4 is a perspective view illustrating a cutout portion of the inner second land portion illustrated in FIG. 3. FIG. 5 is a cross-sectional view of the center land portion shown in FIG. FIG. 6 is an explanatory diagram illustrating an outer second land portion and an outer shoulder land portion of the pneumatic tire illustrated in FIG. 1. FIG. 7 is an explanatory diagram illustrating a center land portion and an outer second land portion of the pneumatic tire illustrated in FIG. 1. FIG. 8 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention. FIG. 9 is a plan view of a tread showing the pneumatic tire of the first conventional example. FIG. 10 is a plan view of a tread showing a pneumatic tire of Conventional Example 2.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire 1 according to an embodiment of the present invention. The figure shows a radial tire for a passenger car as an example of the pneumatic tire 1. Reference sign CL is a tire equator plane.

  The pneumatic tire 1 includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair. Rim cushion rubbers 17 and 17 (see FIG. 1).

  The pair of bead cores 11 and 11 has an annular structure and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the bead portion.

  The carcass layer 13 has a single-layer structure and is bridged in a toroidal shape between the left and right bead cores 11 and 11 to constitute a tire skeleton. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, nylon, polyester, rayon, etc.) with a coating rubber and rolling them, and has an absolute value of 85 [deg] or more and 95. [Deg] The following carcass angle (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction).

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and having a belt angle of 10 [deg] or more and 30 [deg] or less in absolute value. Have. Further, the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure).

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of rim cushion rubbers 17 and 17 are arranged on the outer sides in the tire width direction of the left and right bead cores 11 and 11 and the bead fillers 12 and 12, respectively, and constitute left and right bead portions.

  FIG. 2 is a plan view showing a tread surface of the pneumatic tire 1 shown in FIG. 1. The figure shows a tread pattern of a sports summer tire.

  The pneumatic tire 1 includes three circumferential main grooves 21 to 23 adjacent to each other, one circumferential narrow groove 24 having a narrower width than these circumferential main grooves 21 to 23, and these The circumferential main grooves 21 to 23 and the circumferential narrow grooves 24 are provided in the tread portion with five rows of land portions 31 to 35 (see FIG. 2).

  Here, among the five rows of land portions 31 to 35, the land portion 33 in the center is referred to as a center land portion. The center land portion 33 is on the tire equatorial plane CL. The left and right land portions 32 and 34 adjacent to the center land portion 33 are referred to as second land portions. The left and right land portions 31 and 35 on the outer side in the tire width direction of the left and right second land portions 32 and 34 are referred to as shoulder land portions.

  Further, the second land portion 32 and the shoulder land portion 31 in one region having the center land portion 33 as a boundary are referred to as an inner second land portion and an inner shoulder land portion. Further, the second land portion 34 and the shoulder land portion 35 in the other region are referred to as an outer second land portion and an outer shoulder land portion. These names are related to the vehicle mounting direction of tires to be described later.

  In the configuration of FIG. 2, the three circumferential main grooves 21 to 23 and the one circumferential narrow groove 24 are all straight grooves extending linearly in the tire circumferential direction, and two circumferential main grooves 21, 22 and the circumferential main groove 23 and the circumferential narrow groove 24 are arranged symmetrically with respect to the tire equatorial plane CL. Further, the circumferential narrow groove 24 is disposed at a position that divides the outer second land portion 34 and the outer shoulder land portion 35. Further, the center land portion 33 is a rib continuous in the tire circumferential direction, and the inner second land portion 32 and the outer second land portion 34 are block rows divided in the tire circumferential direction by a plurality of lug grooves 321 and 341. ing. The detailed configuration of each land portion 31 to 35 will be described later.

  The circumferential main groove refers to a circumferential groove having a groove width of 7.0 [mm] or more. The lug groove refers to a lateral groove having a groove width of 2.0 [mm] or more. These groove widths are measured excluding notches and chamfers formed in the groove openings. The sipe described later is a cut formed in the land portion, and generally has a sipe width of less than 2.0 [mm].

[Tire mounting direction]
In addition, the pneumatic tire 1 has a designation (not shown) of a mounting direction to be mounted on the vehicle with the region having the circumferential narrow groove 24 being outside in the vehicle width direction. The designation of the mounting direction can be displayed by, for example, a mark or unevenness attached to the sidewall portion of the tire, or a catalog attached to the tire.

[Circumferential narrow groove]
In this pneumatic tire 1, as described above, the circumferential narrow groove 24 is disposed at a position that partitions the outer second land portion 34 and the outer shoulder land portion 35, and the three circumferential main grooves 21 to 21 are arranged. The groove width is narrower than 23 (see FIG. 2). As a result, the rigidity of the region having the circumferential narrow groove 24 (region on the outer side in the vehicle width direction) is increased, and the dry performance of the tire is improved.

  At this time, the groove width Wd of the circumferential narrow groove 24 and the maximum value Wmax of the groove widths of the three circumferential main grooves 21 to 23 have a relationship of 3.1 ≦ Wmax / Wd ≦ 5.0 ( (See FIG. 2). This ratio Wmax / Wd is a ratio between the maximum value Wmax and the minimum value Wd of the groove widths of all the circumferential grooves (three circumferential main grooves 21 to 23 and the circumferential narrow grooves 24) in the tread portion. .

  For example, in the configuration of FIG. 2, the groove width of the circumferential main groove 23 that divides the center land portion 33 and the outer second land portion 34 is the maximum value Wmax, which is the largest, and the center land portion 33 and the inner second land portion 32 The groove width of the circumferential main groove 22 that divides the inner second land portion 32 and the inner shoulder land portion 31 is the next largest, and the groove width of the circumferential narrow groove 24 is the next largest. The groove width Wd is the smallest. Further, the groove width of the circumferential main groove 21 that divides the inner second land portion 32 and the inner shoulder land portion 31 is set to 2.0 times or more than the groove width Wd of the circumferential narrow groove 24.

[Ratio of groove area between center land and second land]
In the pneumatic tire 1, the groove area ratio S2 of the center land portion 33, the groove area ratio S1 of the inner second land portion 32, and the groove area ratio S3 of the outer second land portion 34 are S2 <S3 <S1. (See FIG. 2). That is, in the three rows of land portions 32 to 34 in the tread portion center region, the groove area ratio S2 of the center land portion 33 that is a rib is the smallest, and the groove area ratio S1 of the inner second land portion 32 is the largest. In such a configuration, when the tire is mounted on the vehicle with the circumferential narrow groove 24 side on the outer side in the vehicle width direction, the rigidity of the outer region in the vehicle width direction (the region having the center land portion 33 and the outer second land portion 34). Is secured. Moreover, the drainage property of the area | region (area | region which has the inner side 2nd land part 32) inside a vehicle width direction is ensured. Thereby, the dry performance and wet performance of the tire are compatible.

  In the above configuration, the groove area ratios S1 to S3 preferably have a relationship of 1.05 ≦ S3 / S2 and 1.05 ≦ S1 / S3. Thereby, the relationship of groove area ratio S1-S3 is optimized.

  The groove area ratio is defined by groove area / (groove area + ground area). The groove area refers to the opening area of the groove on the ground contact surface. The groove refers to a circumferential groove and a lug groove in the tread portion, and does not include sipes, kerfs, and notches. The ground contact area is the contact area between the land and the ground contact surface. In addition, the groove area and the contact area are determined when the tire is mounted on the specified rim and applied with the specified internal pressure, and is placed perpendicular to the flat plate in a stationary state and applied with a load corresponding to the specified load. Measured at the contact surface between the plate and the flat plate.

  Here, the prescribed rim refers to “applied rim” prescribed in JATMA, “Design Rim” prescribed in TRA, or “Measuring Rim” prescribed in ETRTO. The specified internal pressure means “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. The specified load means the “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

[Inner second land and center land]
FIG. 3 is an explanatory diagram illustrating the inner second land portion 32 and the center land portion 33 of the pneumatic tire 1 illustrated in FIG. 1. 4 is a perspective view showing the notch 324 of the inner second land portion 32 shown in FIG. FIG. 5 is a cross-sectional view taken along line A showing the notch groove 332 of the center land portion 33 described in FIG. 3.

  In the pneumatic tire 1, the inner second land portion 32 includes a plurality of first lug grooves 321, a plurality of second lug grooves 322, a plurality of sipes 323, and a plurality of notches 324 (see FIG. 3). ).

  The first lug groove 321 has an open structure that penetrates the inner second land portion 32 and communicates with the left and right circumferential main grooves 21 and 22. Further, the plurality of first lug grooves 321 are arranged at a predetermined interval in the tire circumferential direction, whereby the inner second land portion 32 becomes a block row divided in the tire circumferential direction. For example, in the configuration of FIG. 3, the first lug groove 321 is composed of a straight groove extending in the tire width direction while being inclined at a predetermined angle with respect to the tire circumferential direction.

  Moreover, the 1st lug groove 321 has the bottom upper part 3211 (refer FIG. 3). The bottom upper portion 3211 refers to a portion where the groove depth of the first lug groove 321 is 15% or more and 45% or less with respect to the maximum groove depth of the first lug groove 321. The bottom upper portion 3211 is disposed in a region from the edge portion on the center land portion 33 side to a predetermined position in the inner second land portion 32, and raises the bottom of the first lug groove 321. Specifically, the distance D1 in the tire width direction of the arrangement region of the bottom upper portion 3211 and the width W1 of the inner second land portion 32 have a relationship of 0.30 ≦ D1 / W1 ≦ 0.70.

  The second lug groove 322 has a semi-closed structure that opens to an edge portion on the inner shoulder land portion 31 side of the inner second land portion 32 and terminates in the inner second land portion 32 (see FIG. 3). A plurality of second lug grooves 322 are arranged at predetermined intervals in the tire circumferential direction. Further, the length D2 of the second lug groove 322 in the tire width direction and the width W1 of the inner second land portion 32 have a relationship of 0.40_ ≦ D2 / W1 ≦ 0.60.

  Moreover, the some 1st lug groove 321 and the some 2nd lug groove 322 are mixed and arrange | positioned at predetermined intervals in a tire circumferential direction (refer FIG. 2). For example, in the configuration of FIG. 2, the first lug grooves 321 and the second lug grooves 322 are alternately arranged with a predetermined interval in the tire circumferential direction. However, the present invention is not limited thereto, and for example, two first lug grooves 321 and one second lug groove 322 may be alternately arranged with a predetermined interval in the tire circumferential direction (not shown). In such a configuration, the drainage performance of the tire is improved by disposing more first lug grooves 321 having an open structure than the second lug grooves 322. Conversely, one first lug groove 321 and two second lug grooves 322 may be alternately arranged with a predetermined interval in the tire circumferential direction (not shown). In such a configuration, the number of the second lug grooves 322 having a semi-closed structure is arranged more than the first lug grooves 321, thereby improving the tire dry performance. Thus, the arrangement ratio of the first lug groove 321 and the second lug groove 322 can be appropriately set according to the specification of the tire.

  The sipe 323 is disposed by connecting the second lug groove 322 and the edge portion on the center land portion 33 side of the inner second land portion 32 (see FIG. 3). For example, in the configuration of FIG. 3, the sipe 323 extends from the terminal end of the second lug groove 322 along the extension line of the second lug groove 322 and opens in the circumferential main groove 22.

  The notch 324 is disposed at the edge portion on the inner shoulder land portion 31 side of the inner second land portion 32 (see FIG. 3). The notch 324 has a shape in which the edge portion of the inner second land portion 32 is notched in a pyramid shape (see FIG. 4). A plurality of notches 324 are arranged at predetermined intervals in the tire circumferential direction (see FIG. 2). For example, in the configuration of FIG. 2, the edge portion of the inner second land portion 32 is divided in the tire circumferential direction by a plurality of first lug grooves 321 and a plurality of second lug grooves 322. And every other notch part 324 is arrange | positioned with respect to the area of the edge part of the divided inner 2nd land part 32. As shown in FIG. For this reason, the section having the notch 324 and the section not having the notch 324 are alternately arranged. Further, the notch 324 is arranged from the second lug groove 322 to the first lug groove 321 while the notch width is narrowed from the second lug groove 322 toward the first lug groove 321.

  In the pneumatic tire 1, the center land portion 33 includes a plurality of lug grooves 331, a plurality of cutout grooves 332, and a plurality of cutout portions 333 (see FIG. 3).

  The lug groove 331 has a semi-closed structure that opens to an edge portion on the inner second land portion 32 side of the center land portion 33 and terminates in the center land portion 33. In addition, the lug groove 331 is disposed along an extension line of the second lug groove 322 of the inner second land portion 32.

  At this time, the lug groove 331 of the center land portion 33 may be on a substantially extended line of the second lug groove 322 of the inner second land portion 32. Therefore, the lug groove 331 of the center land portion 33 may be disposed offset in the tire circumferential direction with respect to the extension line of the second lug groove 322 of the inner second land portion 32 (not shown). Specifically, the distance in the tire circumferential direction (offset amount; not shown) between the lug groove 331 of the center land portion 33 and the extension line of the second lug groove 322 of the inner second land portion 32 is the center land portion 33. The width W2 is preferably in the range of ± 50 [%], and more preferably in the range of ± 20 [%]. That is, if the lug groove 331 of the center land portion 33 is within the above range, it can be said that the lug groove 331 is substantially on the extension line of the second lug groove 322 of the inner second land portion 32.

  The notch groove 332 opens at the edge portion on the outer second land portion 34 side of the center land portion 33 and terminates in the center land portion 33 (see FIG. 3). The length D3 of the notch groove 332 in the tire width direction and the width W2 of the center land portion 33 have a relationship of 0.15 ≦ D3 / W2 ≦ 0.35.

  The notch groove 332 has a chamfered portion 3321 that surrounds the groove opening of the notch groove 332. For example, in the configuration of FIG. 3, the notch groove 332 has a chamfered portion 3321 that is formed over the entire circumference of the notch groove 332 along the groove opening and surrounds the end portion of the notch groove 332 in an arc shape. ing. As shown in FIG. 4, the chamfered portion 3321 is a C chamfer formed at the edge portion between the tread surface of the center land portion 33 and the groove wall surface. Further, the groove width Ws of the notch groove 332 and the width Wh of the chamfered portion 3321 have a relationship of 2.0 ≦ Wh / Ws ≦ 3.0. The notch groove 332 having the chamfered portion 3321 is preferable in that drainage can be improved while suppressing a decrease in rigidity of the center land portion 33.

  The notch part 333 is arrange | positioned at the edge part by the side of the inner side 2nd land part 32 of the center land part 33 (refer FIG. 3). Further, the length L1 in the tire circumferential direction of the cutout portion 324 of the inner second land portion 32 and the length L2 in the tire circumferential direction of the cutout portion 333 of the center land portion 33 are 0.45 ≦ L2 / L1 ≦ 0. There are 55 relationships. For example, in the configuration of FIG. 3, the arrangement interval of the first lug grooves 321 of the inner second land portion 32 and the arrangement interval of the lug grooves 331 of the center land portion 33 are set equal. Thereby, the total length of the notch 324 of the inner second land portion 32 and the total length of the notch portion 333 of the center land portion 33 per unit pitch of the tire are set to 0.45 or more and 0.55 or less.

[Outside second land and outside shoulder land]
FIG. 6 is an explanatory diagram showing the outer second land portion 34 and the outer shoulder land portion 35 of the pneumatic tire 1 depicted in FIG. 1.

  In the pneumatic tire 1, the outer second land portion 34 includes a first lug groove 341, a second lug groove 342, and a notch 343 (see FIG. 6).

  The first lug groove 341 has an open structure that penetrates the outer second land portion 34 and communicates with the left and right circumferential main grooves 23 and the circumferential narrow grooves 24. Further, the plurality of first lug grooves 341 are arranged at predetermined intervals in the tire circumferential direction, so that the outer second land portion 34 becomes a block row divided in the tire circumferential direction. For example, in the configuration of FIG. 6, the first lug groove 341 is composed of a straight groove extending in the tire width direction while being inclined at a predetermined angle with respect to the tire circumferential direction.

  Moreover, the 1st lug groove 341 has the bottom upper part 3411 (refer FIG. 6). The bottom upper portion 3411 refers to a portion where the groove depth of the first lug groove 341 is 20% or more and 60% or less with respect to the maximum groove depth of the first lug groove 341. The bottom upper part 3411 is disposed in a region from an edge part on the outer shoulder land part 35 side of the outer second land part 34 to a predetermined position in the outer second land part 34, and raises the groove bottom of the first lug groove 341. Specifically, the distance D4 in the tire width direction of the arrangement region of the bottom upper portion 3411 and the width W3 of the outer second land portion 34 have a relationship of 0.20 ≦ D4 / W3 ≦ 0.50.

  The second lug groove 342 has a semi-closed structure that opens at an edge portion on the center land portion 33 side of the outer second land portion 34 and terminates in the outer second land portion 34 (see FIG. 6). A plurality of second lug grooves 342 are arranged at predetermined intervals in the tire circumferential direction. The length D5 of the second lug groove 342 in the tire width direction and the width W3 of the outer second land portion 34 have a relationship of 0.25 ≦ D5 / W3 ≦ 0.45.

  The notch 343 is disposed at an edge portion of the outer second land portion 34 on the center land portion 33 side (see FIG. 6). The notch 343 has a shape in which the edge portion of the outer second land portion 34 is notched in a pyramid shape. In the configuration of FIG. 6, a notch 343 is disposed over the entire edge portion of the outer second land portion 34.

  Moreover, in this pneumatic tire 1, the outer side shoulder land part 35 has the lug groove 351 and the notch part 352 (refer FIG. 6).

  The lug groove 351 has an open structure that extends in the tire width direction from the edge portion on the circumferential narrow groove 24 side of the outer shoulder land portion 35 and exceeds the tire ground contact end T. Further, the distance W4 in the tire width direction from the edge portion of the outer shoulder land portion 35 on the circumferential narrow groove 24 side to the tire ground contact end T, and the tire width from the edge portion of the outer shoulder land portion 35 on the circumferential narrow groove 24 side. The groove width W5 of the lug groove 351 in the region up to the distance D6 in the direction and the groove width W6 of the lug groove 351 at the tire ground contact edge T are 0.10 ≦ D6 / W4 ≦ 0.55 and 0.55 ≦ W5 / It has a relationship of W6 ≦ 0.75. Therefore, the lug groove 351 has a structure in which the groove width is narrowed at the end on the circumferential narrow groove 24 side.

  The tire ground contact end T is a tire when a tire is mounted on a specified rim and applied with a specified internal pressure, and is placed perpendicular to a flat plate in a stationary state and applied with a load corresponding to the specified load. The maximum width position in the tire axial direction on the contact surface between the flat plate and the flat plate.

[Center land and outer second land]
FIG. 7 is an explanatory diagram showing the center land portion 33 and the outer second land portion 34 of the pneumatic tire 1 depicted in FIG. 1.

  In this pneumatic tire 1, it is preferable that the notch groove 332 of the center land portion 33 is on a substantially extended line of the lug groove 341 of the outer second land portion 34 (see FIG. 7). Thereby, drainage from the notch groove 332 of the center land portion 33 to the lug groove 341 of the outer second land portion 34 is promoted.

  At this time, as shown in FIG. 7, the notch groove 332 of the center land portion 33 may be disposed offset in the tire circumferential direction with respect to the extension line of the lug groove 341 of the outer second land portion 34. Specifically, the distance G in the tire circumferential direction between the notch groove 332 of the center land portion 33 and the extension line of the lug groove 341 of the outer second land portion 34 is ± 50 [%] of the width W2 of the center land portion 33. It is preferably within the range, and more preferably within the range of ± 20 [%]. That is, if the notch groove 332 of the center land portion 33 is within the above range, it can be said that the notch groove 332 is substantially on the extension line of the lug groove 341 of the outer second land portion 34.

[effect]
As described above, the pneumatic tire 1 includes three circumferential main grooves 21 to 23 and one circumferential narrow groove 24 having a groove width Wd narrower than the circumferential main grooves 21 to 23. A tread of a row of center land portions 33, a pair of left and right second land portions 32 and 34, and a pair of left and right shoulder land portions 31 and 35, which are defined by the circumferential main grooves 21 to 23 and the circumferential narrow grooves 24. (See FIG. 2). Further, the circumferential narrow groove 24 is disposed at a position that divides the outer second land portion 34 and the outer shoulder land portion 35. The center land portion 33 is a rib continuous in the tire circumferential direction, and the inner second land portion 32 and the outer second land portion 34 are block rows divided in the tire circumferential direction by a plurality of lug grooves 321 and 341. . The groove area ratio S2 of the center land portion 33, the groove area ratio S1 of the inner second land portion 32, and the groove area ratio S3 of the outer second land portion 34 have a relationship of S2 <S3 <S1. Further, the groove width Wd of the circumferential narrow groove 24 and the maximum value Wmax of the groove widths of the other three circumferential main grooves 21 to 23 have a relationship of 3.1 ≦ Wmax / Wd ≦ 5.0. .

  In this configuration, (1) the groove area ratio S2 of the center land portion 33, the groove area ratio S1 of the inner second land portion 32, and the groove area ratio S3 of the outer second land portion 34 are S2 <S3 <S1. Therefore, the rigidity of the center land portion 33 and the rigidity of the outer second land portion 34 are increased, and the drainage performance of the region having the inner second land portion 32 is improved. Further, (2) in the configuration having the groove area ratios S1 to S3, the groove width Wd of the circumferential narrow groove 24 and the maximum value Wmax of the groove widths of the other three circumferential main grooves 21 to 23 are: By having a relationship of 3.1 ≦ Wmax / Wd ≦ 5.0, the rigidity of the region having the circumferential narrow groove 24 is increased. Accordingly, there is an advantage that the dry performance and the wet performance of the tire are compatible when the tire is mounted on the vehicle with the region on the circumferential narrow groove 24 side being the outer side in the vehicle width direction.

  In the pneumatic tire 1, the inner second land portion 32 opens to the first lug groove 321 penetrating the inner second land portion 32 and the edge portion on the inner shoulder land portion 31 side of the inner second land portion 32. A second lug groove 322 that terminates in the inner second land portion 32 (see FIG. 2). Moreover, the some 1st lug groove 321 and the some 2nd lug groove 322 are mixed and arrange | positioned at predetermined intervals in the tire circumferential direction. Moreover, the 1st lug groove 321 has the bottom upper part 3211 in the area | region from the edge part by the side of the center land part 33 of the inner side second land part 32 to the predetermined position in the inner side second land part 32 (refer FIG. 3). In this configuration, since the first lug groove 321 has the bottom upper part 3211 at the end on the center land portion 33 side, the rigidity of the center land portion 33 can be reinforced while ensuring the drainage of the first lug groove 321. Thereby, there exists an advantage which can make dry performance and wet performance of a tire compatible.

  In this pneumatic tire 1, the distance D1 in the tire width direction of the arrangement region of the bottom upper portion 3211 and the width W1 of the inner second land portion 32 have a relationship of 0.30 ≦ D1 / W1 ≦ 0.70. (See FIG. 3). Thereby, there exists an advantage by which the arrangement | positioning area | region of the bottom upper part 3211 is optimized.

  Further, in the pneumatic tire 1 according to the present invention, the inner second land portion 32 has a sipe 323 that connects the second lug groove 322 and the edge portion on the center land portion 33 side of the inner second land portion 32 (FIG. 3). reference). In such a configuration, the sipe 323 extends in the tire width direction and extends the second lug groove 322, thereby dividing the inner second land portion 32 in the tire circumferential direction. Accordingly, there is an advantage that the WET performance is improved by the edge effect of sipe without reducing the block rigidity.

  Further, in the pneumatic tire 1, the length D2 of the second lug groove 322 in the tire width direction and the width W1 of the inner second land portion 32 have a relationship of 0.40 ≦ D2 / W1 ≦ 0.60. (See FIG. 3). With such a configuration, there is an advantage that the length D2 of the second lug groove 322 is optimized and the dry performance and wet performance of the tire can be compatible.

  In the pneumatic tire 1, the center land portion 33 has a plurality of notch grooves 332 at the edge portion on the outer second land portion 34 side, and these notch grooves 332 surround the groove opening of the notch groove 332. A chamfer 3321 is provided (see FIG. 3). In such a configuration, the center land portion 33 has the notch groove 332, so that the wet performance of the tire is improved. At this time, the notch groove 332 has the chamfered portion 3321, so that the wet performance of the tire is further improved. On the other hand, in the configuration in which the notch groove 332 includes the chamfered portion 3321, the rigidity of the edge portion on the outer second land portion 34 side is ensured. Accordingly, there is an advantage that the dry performance and the wet performance of the tire are compatible when the tire is attached to the vehicle with the region on the circumferential narrow groove 24 side being the outer side in the vehicle width direction.

  Moreover, in this pneumatic tire 1, the inner second land portion 32 has a plurality of notches 324 at the edge portion on the inner shoulder land portion 31 side (see FIG. 3). In such a configuration, the groove volume of the circumferential main groove 21 is increased by the notch 324, and the wettability of the tire is improved. Further, the rigidity of the inner second land portion 32 is higher than the configuration in which the circumferential main groove 21 is widened. Thereby, there exists an advantage which the dry performance and wet performance of a tire make compatible.

  Moreover, in this pneumatic tire 1, the center land part 33 has the lug groove 331 which opens in the edge part by the side of the inner side second land part 32, and terminates in the center land part 33 (refer FIG. 3). Further, the lug groove 331 is on a substantially extended line of the second lug groove 322 of the inner second land portion 32. In such a configuration, the lug groove 331 of the center land portion 33 is arranged on the extension line of the second lug groove 322 that terminates in the inner second land portion 32, so that the wettability of the tire is ensured.

  Further, in the pneumatic tire 1, the outer shoulder land portion 35 has a lug groove 351 extending in the tire width direction from the edge portion on the circumferential narrow groove 24 side beyond the tire ground contact end T (see FIG. 6). . Further, the distance W4 in the tire width direction from the edge portion of the outer shoulder land portion 35 on the circumferential narrow groove 24 side to the tire ground contact end T, and the tire width from the edge portion of the outer shoulder land portion 35 on the circumferential narrow groove 24 side. The groove width W5 of the lug groove 351 in the region up to the distance D6 in the direction and the groove width W6 of the lug groove 351 at the tire ground contact edge T are 0.40 ≦ D6 / W4 ≦ 0.60 and 0.55 ≦ W5 / It has a relationship of W6 ≦ 0.75. In such a configuration, the drainage performance of the tire is improved by opening the lug groove 351 of the outer shoulder land portion 35 at the edge portion on the circumferential narrow groove 24 side. Further, the lug groove 351 narrows the groove width in a predetermined region (region of distance D6) of the opening on the circumferential narrow groove 24 side, whereby the rigidity of the outer shoulder land portion 35 is ensured. Thereby, there exists an advantage which the dry performance and wet performance of a tire make compatible.

  Moreover, in this pneumatic tire 1, the outer second land portion 34 has a lug groove 341 that penetrates the outer second land portion 34 (see FIG. 6). Further, the lug groove 341 has a bottom upper portion 3411 in a region from an edge portion on the outer shoulder land portion 35 side of the outer second land portion 34 to a predetermined position in the outer second land portion 34. In such a configuration, the outer second land portion 34 has the lug groove 3411, so that the drainage performance of the tire is improved. In addition, since the lug groove 341 has a bottom upper portion, the rigidity of the outer second land portion 34 is ensured. Thereby, there exists an advantage which the dry performance and wet performance of a tire make compatible.

  Moreover, in this pneumatic tire 1, the center land part 33 has the notch part 333 in the edge part by the side of the inner side 2nd land part 32 (refer FIG. 3). Further, the length L1 in the tire circumferential direction of the notch 333 in the center land portion 33 and the length L2 in the tire circumferential direction of the notch 324 in the inner second land portion 32 are 0.45 ≦ L2 / L1 ≦ 0. There are 55 relationships. In such a configuration, the inner second land portion 32 and the center land portion 33 have the cutout portions 324 and 333, respectively, thereby increasing the groove volume and improving the wet performance of the tire. Moreover, the rigidity of the inner second land portion 32 having a large groove area ratio S1 is ensured by setting the length L2 of the notch 324 of the inner second land portion 32 to be short. Thereby, there exists an advantage which the dry performance and wet performance of a tire make compatible.

  Moreover, in this pneumatic tire 1, the notch groove 332 of the center land part 33 is on the substantially extended line of the lug groove 341 of the outer side second land part 34 (refer FIG. 7). In such a configuration, drainage from the notch groove 332 of the center land portion 33 to the lug groove 341 of the outer second land portion 34 is promoted. Thereby, there exists an advantage which the wettability of a tire improves.

  In addition, the pneumatic tire 1 has a designation of a mounting direction to be mounted on the vehicle with the circumferential narrow groove 24 side on the outer side in the vehicle width direction (see FIG. 2). In such a configuration, the tire dry performance is improved by disposing the region on the circumferential narrow groove 24 side having high rigidity on the outer side in the vehicle width direction. Moreover, since the inner second land portion 32 having a large groove area ratio S1 is disposed on the inner side in the vehicle width direction, the wet performance of the tire is improved. Thereby, there exists an advantage which the dry performance and wet performance of a tire make compatible.

  FIG. 8 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention. FIGS. 9 and 10 are tread plan views showing the pneumatic tires of Conventional Examples 1 and 2. FIG.

  In this performance test, evaluations on (1) dry performance and (2) wet performance were performed on a plurality of different pneumatic tires (see FIG. 8). In this performance test, a pneumatic tire with a tire size of 275 / 35R20 is assembled to a rim with a rim size of 20 × 9JJ (OE designated standard rim), and the pneumatic tire is given a pneumatic pressure of 260 [kPa] and a maximum load specified by JATMA. Is done. A pneumatic tire is mounted on a large sedan of a foreign vehicle that is a test vehicle.

  (1) In the evaluation regarding the dry performance, the test vehicle travels on a test course having a flat circuit at 60 [km / h] to 100 [km / h]. Then, the test driver performs sensory evaluation on the steering performance at the time of lane change and cornering and the stability at the time of straight traveling. This evaluation is performed by index evaluation based on Conventional Example 2 (100), and the larger the value, the better.

  (2) In the evaluation on wet performance, a test vehicle travels on a wet road surface, and an ABS (anti-locked braking system) braking distance from an initial speed of 100 [km / h] is measured. Then, based on the measurement result, index evaluation is performed with the conventional example 1 as a reference (100). An evaluation result is so preferable that the numerical value is large.

  The pneumatic tire 1 of the first embodiment has the tread pattern shown in FIG. 2 and is mounted on the vehicle with the region on the circumferential narrow groove 24 side being outside in the vehicle width direction. The groove area ratio S2 of the center land portion 33, the groove area ratio S1 of the inner second land portion 32, and the groove area ratio S3 of the outer second land portion 34 are S1 = 12.5, S2 = 9.3, S3 = 10.8, and there is a relationship of S3 / S2 = 1.16 and S1 / S3 = 1.16. Further, the groove width Wd of the circumferential narrow groove 24 is Wd = 5.8 [mm]. In addition, the widths W1 to W6 in FIGS. 3 and 6 are W1 = 27.5 [mm], W2 = 30.4 [mm], W3 = 28.0 [mm], W4 = 56.0 [mm], W6 = 3.9 [mm]. Moreover, the pneumatic tire 1 of Examples 2-14 is a modification of the pneumatic tire 1 of Example 1.

  The pneumatic tires of Conventional Examples 1 and 2 have the tread patterns of FIGS. 9 and 10 respectively.

  As shown in the test results, in the pneumatic tires 1 of Examples 1 to 14, it can be seen that both the dry performance and the wet performance of the tire can be achieved.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 11 Bead core, 12 Bead filler, 13 Carcass layer, 14 Belt layer, 141, 142 Cross belt, 15 Tread rubber, 16 Side wall rubber, 17 Rim cushion rubber, 21-23 Circumferential main groove, 24 laps Direction narrow groove, 31 inner shoulder land, 32 inner second land, 321 first lug groove, 3211 bottom top, 322 second lug groove, 323 sipe, 324 notch, 33 center land, 331 lug groove, 332 notch Groove, 3321 Chamfered portion, 333 Notched portion, 34 Outer second land portion, 341 First lug groove, 3411 Bottom upper portion, 342 Second lug groove, 343 Notched portion, 35 Outer shoulder land portion, 351 Lug groove, 352 Notched portion

Claims (13)

Three circumferential main grooves, one circumferential narrow groove having a narrower width than the circumferential main groove, and a row of centers divided into the circumferential main groove and the circumferential narrow groove A pneumatic tire comprising a land portion, a pair of left and right second land portions, and a pair of left and right shoulder land portions in a tread portion,
The second land portion and the shoulder land portion in one region with the center land portion as a boundary are called an inner second land portion and an inner shoulder land portion, and the second land portion and the shoulder land portion in the other region are When we call the outer second land and outer shoulder land,
The circumferential narrow groove is disposed at a position that divides the outer second land portion and the outer shoulder land portion,
The center land portion is a rib continuous in the tire circumferential direction, and the inner second land portion and the outer second land portion are block rows divided in the tire circumferential direction by a plurality of lug grooves,
The groove area ratio S2 of the center land portion, the groove area ratio S1 of the inner second land portion, and the groove area ratio S3 of the outer second land portion have a relationship of S2 <S3 <S1, and
The groove width Wd of the circumferential narrow groove and the maximum value Wmax of the other three circumferential main grooves have a relationship of 3.1 ≦ Wmax / Wd ≦ 5.0. Pneumatic tires. The inner second land portion has a first lug groove that penetrates the inner second land portion, and a second end that opens in the inner shoulder land portion side edge portion of the inner second land portion and terminates in the inner second land portion. With lug grooves,
A plurality of the first lug grooves and a plurality of the second lug grooves are mixed and arranged with a predetermined interval in the tire circumferential direction, and
2. The pneumatic tire according to claim 1, wherein the first lug groove has a bottom upper portion in a region from an edge portion on the center land portion side of the inner second land portion to a predetermined position in the inner second land portion.   3. The pneumatic tire according to claim 2, wherein a distance D <b> 1 in the tire width direction of the arrangement region of the bottom upper portion and a width W <b> 1 of the inner second land portion have a relationship of 0.30 ≦ D1 / W1 ≦ 0.70. .   The pneumatic tire according to claim 2 or 3, wherein the inner second land portion includes a sipe that connects the second lug groove and an edge portion of the inner second land portion on the center land portion side.   The length D2 in the tire width direction of the second lug groove and the width W1 of the inner second land portion have a relationship of 0.40 ≦ D2 / W1 ≦ 0.60. Pneumatic tire described in one.   The center land portion has a plurality of cutout grooves in an edge portion on the outer side second land portion side, and the cutout groove has a chamfered portion surrounding a groove opening of the cutout groove. A pneumatic tire according to any one of the above.   The pneumatic tire according to any one of claims 1 to 6, wherein the inner second land portion has a plurality of notches at an edge portion on the inner shoulder land portion side.   The center land portion has a lug groove that opens at an edge portion on the inner second land portion side and terminates in the center land portion, and the lug groove is the second lug groove of the inner second land portion. The pneumatic tire according to any one of claims 2 to 7, which is on a substantially extended line. The outer shoulder land portion has a lug groove extending in the tire width direction from the edge portion on the circumferential narrow groove side beyond the tire ground contact end, and
The distance W4 in the tire width direction from the edge portion on the circumferential narrow groove side of the outer shoulder land portion to the tire ground contact end, and the distance in the tire width direction from the edge portion on the circumferential narrow groove side of the outer shoulder land portion The groove width W5 of the lug groove in the region up to D6 and the groove width W6 of the lug groove at the tire ground contact edge are 0.40 ≦ D6 / W4 ≦ 0.60 and 0.55 ≦ W5 / W6 ≦ 0. The pneumatic tire according to claim 1, having a relationship of 75.   The outer second land portion has a lug groove penetrating the outer second land portion, and the lug groove is located in the outer second land portion from an edge portion on the outer shoulder land portion side of the outer second land portion. The pneumatic tire according to any one of claims 1 to 9, which has a bottom upper portion in a region up to a predetermined position.   The center land portion has a notch at an edge portion on the inner second land portion side, and a length L1 in the tire circumferential direction of the notch portion of the center land portion, and the notch of the inner second land portion. The pneumatic tire according to claim 7, wherein a length L2 of the tire circumferential direction of the portion has a relationship of 0.45 ≦ L2 / L1 ≦ 0.55.   The pneumatic tire according to claim 10, wherein the notch groove is on a substantially extended line of a lug groove of the outer second land portion.   The pneumatic tire according to any one of claims 1 to 12, which has a designation of a mounting direction to be mounted on a vehicle with the circumferential narrow groove side being an outer side in the vehicle width direction.

Images