JP2013256159A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having a pitch variation structure, configured to improve tire steering stability.SOLUTION: A pneumatic tire 1 includes a plurality of lug grooves arranged on left and right shoulder land parts 32 and extended in a tire width direction. The lug grooves 42 are arranged in a tire circumferential direction with a predetermined arrangement pattern having multiple kinds of pitch lengths Pa-Pc. In cross-sectional view in a tire meridian direction, radii Ra, Rc constituting at least 60% of a profile line in a region X from a tire ground end T to a tread end TE are minimum in a section having the minimum pitch Pa of the multiple kinds of pitch lengths Pa-Pc, and they are maximum in a section having the maximum pitch length Pc.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving the steering stability performance of a tire in a configuration employing a pitch variation structure.

  In recent pneumatic tires, a pitch variation structure in which land-type lug grooves are arranged in a plurality of pitch lengths in the tire circumferential direction is employed in order to reduce pattern noise during traveling. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

JP 2007-132867 A

  Here, in the pneumatic tire adopting the pitch variation structure as described above, the rigidity of each section of the land portion partitioned by the lug groove becomes non-uniform, so there is a problem that the steering stability performance of the tire is lowered. .

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving the steering stability performance of the tire in a configuration employing a pitch variation structure.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a plurality of circumferential main grooves extending in a tire circumferential direction, a plurality of land portions defined by the circumferential main grooves, and the plurality of land portions. A pneumatic tire comprising a plurality of lug grooves arranged in left and right land portions (hereinafter referred to as shoulder land portions) on the outermost side in the tire width direction among the land portions and extending in the tire width direction, The plurality of lug grooves are arranged in a tire circumferential direction in a predetermined arrangement pattern having a plurality of types of pitch lengths, and a profile in a region X from a tire contact edge to a tread edge in a sectional view in the tire meridian direction Radius constituting at least 60% of the line is minimum in the section having the minimum pitch length among the plurality of types of pitch lengths and maximum in the section having the maximum pitch length. And features.

  In the pneumatic tire according to the present invention according to the present invention, the lug groove in the shoulder land portion has a pitch variation structure, whereby there is an advantage that the pitch noise is reduced and the noise performance of the tire is improved. Further, by adjusting the radius of the profile line in the non-ground area, the rigidity of each section partitioned by the lug groove is made uniform. Thereby, there exists an advantage which the steering stability performance of a tire improves.

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 illustrating a shoulder land portion of the pneumatic tire illustrated in FIG. 2. 4 is an explanatory view showing a shoulder land portion of the pneumatic tire shown in FIG. FIG. 5 is an explanatory diagram illustrating a shoulder land portion of the pneumatic tire illustrated in FIG. 2. FIG. 6 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  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 is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form 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 rolling a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber and having an absolute value of 85 [deg]. A carcass angle of 95 [deg] or less (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction). In the configuration of FIG. 1, the carcass layer 13 has a single-layer structure composed of a single carcass ply. However, the present invention is not limited to this, and the carcass layer 13 has a multilayer structure formed by laminating a plurality of carcass plies. Also good.

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, 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 belt cover 143 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coat rubber, and has a belt angle of 10 [deg] or more and 45 [deg] or less in absolute value. Further, the belt cover 143 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 141 and 142.

  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. This figure shows a general block pattern employing a pitch variation structure.

  The pneumatic tire 1 includes a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction, a plurality of land portions 31 and 32 partitioned into the circumferential main grooves 21 and 22, and the land The tread portion includes a plurality of lug grooves 41 and 42 arranged in the portions 31 and 32 (see FIG. 2).

  For example, in the configuration of FIG. 2, the three circumferential main grooves 21 and 22 are arranged symmetrically about the tire equatorial plane CL. The circumferential main grooves 21 and 22 define two rows of center land portions 31 and 31 and a pair of left and right shoulder land portions 32 and 32. All the land portions 31 and 32 have a plurality of lug grooves 41 and 42 extending in the tire width direction, respectively. Moreover, these lug grooves 41 and 42 have an open structure that penetrates the land portions 31 and 32 in the tire width direction, and are arranged at predetermined intervals in the tire circumferential direction. Thereby, all the land parts 31 and 32 become the block row | line | column divided | segmented into the some block 311a-311c, 321a-321c.

  In addition, the circumferential direction main groove means the circumferential direction groove | channel which has a groove width of 5.0 [mm] or more. The lug groove refers to a lateral groove having a groove width of 1.5 [mm] or more. These groove widths are measured excluding notches and chamfers formed in the groove openings.

  In the configuration of FIG. 2, as described above, all the lug grooves 41 and 42 have an open structure, and all the land portions 31 and 32 are in a block row. However, the present invention is not limited to this, and the lug grooves 41 and 42 have a closed structure or semi-closed structure that terminates in the land portions 31 and 32, so that the land portions 31 and 32 are ribs that continue in the tire circumferential direction. good. Moreover, each lug groove 41 and 42 may have a mutually different groove width.

[Pitch variation structure of lug groove]
Moreover, in this pneumatic tire 1, the lug grooves 41 and 42 of each land part 31 and 32 are arrange | positioned in the tire circumferential direction by the predetermined sequence pattern which has multiple types of pitch length (pitch variation structure). In such a configuration, the frequency of noise generated during traveling is dispersed, and pattern noise is reduced. Moreover, the load load to each block 311a-311c and 321a-321c is optimized, and uneven wear is suppressed.

  For example, in the configuration of FIG. 2, the lug grooves 41 and 42 of the land portions 31 and 32 have a predetermined arrangement having three types of pitch lengths Pa, Pb, and Pc (Pa <Pb <Pc) of small, medium, and large. It is arranged in the tire circumferential direction in a pattern. The land portions 31 and 32 are partitioned by the lug grooves 41 and 42 into a plurality of blocks 311a to 311c and 321a to 321c having three types of circumferential lengths of small, medium, and large.

  Note that the types of pitch length are not limited to three, and may be two or more than four. A general pneumatic tire employs a pitch variation structure in which three to five pitch lengths are randomly arranged.

[Radius in the non-ground area of the shoulder land]
3-5 is explanatory drawing which shows the shoulder land part of the pneumatic tire described in FIG. These drawings respectively show an A sectional view (FIG. 3), a B sectional view (FIG. 4), and a C sectional view (FIG. 5) of the non-grounding region X of the shoulder land portion 32 in FIG. 2. 4 and 5 indicate profile lines of the non-ground region X in FIG.

  In general, in the configuration having the pitch variation structure as described above, the rigidity of each section of the land portion defined by the lug grooves is not uniform, which causes a problem that the steering stability performance of the tire is deteriorated.

  Therefore, in the pneumatic tire 1, the following configuration is adopted to reduce the rigidity difference between the blocks 321a to 321c in the shoulder land portion 32.

  First, a region X from the tire ground contact edge T to the tread edge TE is taken. This region X is a non-grounding region outside the shoulder land portion 32 in the tire width direction, and is formed on the left and right sides of the tire. In the configuration of FIG. 1, the region X is on the tread rubber 15. 2, in the region X, the shoulder land portion 32 is divided in the tire circumferential direction by a plurality of lug grooves 42, and a plurality of blocks 321a to 321c are partitioned.

  Here, the tire ground contact end T is 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. The maximum width position in the tire axial direction on the contact surface between the tire and the flat plate. The tread end portion refers to both end portions of the tread pattern portion of the tire when the tire is mounted on a specified rim to apply a specified internal pressure and to be in an unloaded state.

  The specified rim refers to “applied rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined 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.

  Next, the radiuses Ra to Rc of the profile line in the region X are considered in a cross-sectional view in the tire meridian direction (see FIGS. 3 to 5). This profile line is a profile line of the shoulder land portion 32 and is defined by excluding irregularities such as lug grooves 42 and decorative grooves (not shown). If the profile line has a straight line portion, the radius of the straight line portion is infinite (∞).

  For example, in the configuration of FIG. 2, the profile line (see FIG. 3) of the section having a small pitch length Pa is composed of a single arc that is convex toward the outside of the tire, and has a certain radius Ra. Moreover, the profile line (refer FIG. 4) of the area | region which has intermediate pitch length Pb consists of a single circular arc which protrudes toward the tire exterior, and has fixed radius Rb. Further, the profile line (see FIG. 5) of the section having a large pitch length Pc is formed of a single straight line and has a radius Rc (= ∞).

  At this time, the radius Ra to Rc of the profile line of each section is minimum in the section having the minimum pitch length Pa and maximum in the section having the maximum pitch length Pc. That is, the radius of the profile line is small in the section having the small pitch length Pa, and conversely, the radius of the profile line is large in the section having the large pitch length Pc.

  For example, in the configuration of FIG. 2, the left and right shoulder land portions 32, 32 have a plurality of lug grooves 42, and the plurality of lug grooves 42 have three types of pitch lengths Pa, Pb, small, medium, and large. , Pc (Pa <Pb <Pc) is arranged in the tire circumferential direction in a predetermined arrangement pattern. Further, the radius Ra (see FIG. 3) of the section having the smallest pitch length Pa, the radius Rb (see FIG. 4) of the section having the intermediate pitch length Pb, and the radius Rc (see FIG. 4) of the section having the largest pitch length Pc. 5) has a relationship of Ra <Rb <Rc. Further, the radii Ra to Ra of each section have a relationship of 1.1 ≦ Rb / Ra and 1.1 ≦ Rc / Rb. Further, the profile line of the section having the largest pitch length Pc is a straight line as described above, and the radius Rc is Rc = ∞. For this reason, in the section having a small pitch length Pa, the non-grounding area X of the block 321a has a round shape, and in the section having a large pitch Pc, the non-grounding area X of the block 321c has a planar shape.

  In this pneumatic tire 1, in the configuration in which the lug groove 42 of the shoulder land portion 32 has a pitch variation structure (see FIG. 2), the radii Ra to Rc of the profile line of the non-grounding region X have the maximum pitch length Pa. It becomes the minimum (Ra) in the section (see FIG. 3), and the maximum (Rc) in the section having the minimum pitch length Pc (see FIG. 5). Thereby, the rigidity of the blocks 321a to 321c in each section of the shoulder land portion 32 is made uniform, and the steering stability performance of the tire is improved.

  In this pneumatic tire 1, the minimum pitch length Pmin (= Pa) and the maximum pitch length Pmax (= Pc) have a relationship of 1.3 ≦ Rmax / Rmin ≦ 1.8. Is preferred. Thereby, pitch length Pa-Pc of each block 321a-321c of the shoulder land part 32 is optimized, and pitch noise is reduced effectively.

  Moreover, in this pneumatic tire 1, the ratios Wb / Wa and Wc / Wa of the ground contact widths Wa to Wc of the blocks 321a to 321c of the shoulder land portion 32 defined by the lug grooves 42 are 0.9 or more and 1.1. It is preferable to be within the following range. That is, it is preferable that each of the blocks 321a to 321c has a uniform ground width Wa to Wc. Thereby, the uniformity of a tire improves.

  Further, in the pneumatic tire 1, the sectional area of each block 321 a to 321 c of the shoulder land portion 32 partitioned by the lug groove is maximum in a section having the minimum pitch length Pa in the sectional view in the tire meridian direction. Therefore, it is preferable that the distance is minimum in the section having the maximum pitch length Pc. Thereby, the rubber volume of each block 321a-321c is equalized.

  For example, in the configuration of FIG. 2, when the cross-sectional area of the block 321a in a section having a small pitch length Pa is used as a reference (see FIG. 3), the cross-sectional area of the block 321b is in a section having an intermediate pitch length Pb. The cross-sectional area of the block 321c is minimized (see FIG. 5) in a section that is smaller (see FIG. 4) and has a large pitch length Pc. At this time, as shown in the comparison of FIGS. 3 to 5, the radius Ra to Rc of the profile line of each section in the non-grounding region X is changed, so that the rubber volumes of the blocks 321 a to 321 c are adjusted. Specifically, on the basis of the rubber volume of the block 321a of the section having a small pitch length Pa, the profile line of the section having the intermediate pitch length Pb has a larger radius Rb (> Ra). The tread rubber 15 in the non-grounding region X is thinned. Similarly, since the profile line of the section having the large pitch length Pc has a larger radius Rc (> Rb), the tread rubber 15 in the non-grounding region X in this section is thinned.

  In the configuration of FIG. 2, as described above, the plurality of lug grooves 42 are arranged in the tire circumferential direction in an array pattern having three types of pitch lengths Pa to Pc. However, the present invention is not limited to this, and the above-described configuration can be similarly applied to a configuration (not shown) in which the plurality of lug grooves 42 are arranged in the tire circumferential direction in an array pattern having four or more types of pitch lengths. Specifically, the profile line of the non-grounding region X has a smaller radius as the section has a smaller pitch length, and conversely, the profile line of the non-grounded region X becomes more as the section having a larger pitch length. By having a large radius, a similar configuration can be realized.

  In the configuration of FIG. 5, the profile line of the section having the maximum pitch length Pc is a straight line. However, the present invention is not limited to this, and the profile line in this section may be an arc close to a straight line (not shown). Specifically, if the radius Rc of the profile line is 1000 [mm] ≦ Rc, it can be said that the profile line is a straight line.

  In the configurations of FIGS. 3 to 5, the profile line of the non-ground region X is configured by a single arc (FIGS. 3 and 4) or a single straight line (FIG. 5). However, the present invention is not limited to this, and the profile line may have a configuration in which a plurality of arcs are connected, a configuration in which a plurality of straight lines are connected, or a configuration in which arcs and straight lines are connected (illustrated). (Omitted). In these configurations, the radiuses Ra to Rc constituting most of the non-grounding region X (at least 60%) are minimum in the section having the minimum pitch length Pa, and in the section having the maximum pitch length Pc. It is sufficient to have the maximum configuration.

[effect]
As described above, the pneumatic tire 1 includes a plurality of circumferential main grooves 21 and 22 that extend in the tire circumferential direction, and a plurality of land portions 31 that are partitioned by the circumferential main grooves 21 and 22. , 32 and a plurality of lug grooves 42 arranged in the left and right shoulder land portions 32, 32 on the outermost side in the tire width direction and extending in the tire width direction among these land portions 31, 32 (see FIG. 2). The plurality of lug grooves 42 are arranged in the tire circumferential direction in a predetermined arrangement pattern having a plurality of types of pitch lengths Pa to Pc (pitch variation structure). Further, in a cross-sectional view in the tire meridian direction, the radiuses Ra to Rc constituting at least 60% of the profile line in the region X from the tire ground contact edge T to the tread edge TE are a plurality of types of pitch lengths Pa to Pc. Among these, it becomes the minimum in the section having the minimum pitch length Pa, and the maximum in the section having the maximum pitch length Pc (see FIGS. 3 and 5).

  In such a configuration, the lug groove 42 of the shoulder land portion 32 has a pitch variation structure (see FIG. 2), so that there is an advantage that the pitch noise is reduced and the noise performance of the tire is improved. Further, by adjusting the radii Ra to Rc of the profile line of the non-grounding region X, the rigidity of each section partitioned by the lug groove 42 (the rigidity of the blocks 321a to 321c) is made uniform. Thereby, there exists an advantage which the steering stability performance of a tire improves.

  In the pneumatic tire 1, the plurality of lug grooves are arranged in the tire circumferential direction in a predetermined arrangement pattern having at least three types of pitch lengths Pa, Pb, and Pc, that is, small, medium, and large (see FIG. 2). ). Further, a radius Ra of a section having a small pitch length Pa, a radius Rb of a section having a middle pitch length Pb, and a radius Rc of a section having a large pitch length Pc are Ra <Rb <Rc. Have the relationship. Thereby, the rigidity of the land part (block 321a-321c) in each area is made more uniform, and there exists an advantage which the steering stability performance of a tire improves.

  Further, in the pneumatic tire 1, the profile line of the section having the maximum pitch length Pc among the plurality of types of pitch lengths Pa to Pc is a straight line (Rc = ∞) (see FIG. 5). As a result, the degrees of freedom of the radius Ra and Rb in the profile lines of the other sections are expanded, and there is an advantage that the rigidity of the land portions (blocks 321a to 321c) in each section can be made uniform efficiently.

  Further, in the pneumatic tire 1, the minimum pitch length Pmin (= Pa) and the maximum pitch length Pmax (= Pc) among a plurality of types of pitch lengths Pa to Pc are 1.3 ≦ Pmax /. Pmin ≦ 1.8 (see FIG. 2). Thereby, there exists an advantage by which the pitch length Pa-Pc of each block 321a-321c of the shoulder land part 32 is optimized. That is, by satisfying 1.3 ≦ Pmax / Pmin, the degree of freedom in setting each pitch length Pa to Pc is expanded, and pitch noise is effectively reduced. Further, since Pmax / Pmin ≦ 1.8, the difference in rigidity of the land portions (blocks 321a to 321c) in each section is reduced. Thereby, the rigidity of the land part in each area can be equalized easily by adjusting the radius Ra-Rc of the profile line of each area.

  In the pneumatic tire 1, the ratio of the ground contact widths Wa to Wc of the portions (blocks 321 a to 321 c) of the shoulder land portion 32 partitioned by the lug grooves 42 is in the range of 0.9 or more and 1.1 or less. (See FIG. 2). Thereby, the ground contact widths Wa to Wc of each section of the shoulder land portion 32 are made uniform, and there is an advantage that the uniformity and the steering stability performance of the tire are improved.

  Further, in the pneumatic tire 1, the cross-sectional area of each portion of the shoulder land portion 32 partitioned by the lug groove 42 is the maximum in the section having the minimum pitch length Pa in the cross-sectional view in the tire meridian direction, It becomes the minimum in the section having the maximum pitch length Pc (see FIGS. 3 and 5). Thereby, the rubber volume of each block 321a-321c is equalized, and there exists an advantage which the steering stability performance of a tire improves. In particular, by reducing the rubber volume in the section having the maximum pitch length Pc, there is an advantage that heat generation during tire rolling is suppressed and tire rolling resistance is reduced.

  FIG. 6 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

In this performance test, (1) steering stability performance and (2) rolling resistance were evaluated for a plurality of different pneumatic tires (see FIG. 6). In this performance test, a pneumatic tire having a tire size of 195 / 65R15 91H is assembled to a rim having a rim size of 15 × 6 J, and a pneumatic pressure of 210 [kPa] and a maximum load specified by JATMA are applied to the pneumatic tire. The pneumatic tire is mounted on a domestic sedan with a displacement of 1800 [cc], which is a test vehicle.
(1) In the handling stability evaluation, the test vehicle runs on the test course, and a specialized test driver performs a feeling evaluation on lane change performance and cornering performance. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (2) In the evaluation relating to rolling resistance, a drum testing machine having a drum diameter of 1707 [mm] is used, and the resistance force at a load of 4 [kN] and a speed of 50 [km / h] is measured and evaluated. In this evaluation, index evaluation based on the conventional example as a reference (100) is performed, and the larger the value, the smaller the rolling resistance, which is preferable.

  The pneumatic tire 1 of Examples 1-4 has the structure described in FIGS. Moreover, the groove width of the lug groove 42 of the shoulder land portion 32 is in the range of 2.0 [mm] or more and 10.0 [mm] or less, and the lug groove 42 having a larger pitch length has a larger groove width. Further, the ground contact widths Wa to Wc of the blocks 321a to 321c of the shoulder land portion 32 are all 130 [mm].

  In the pneumatic tire of the conventional example, the radius of the profile line of the non-grounding region X in the tread pattern of FIG. 2 has the round shape described in FIG.

  As shown in the test results, in the pneumatic tires 1 of Examples 1 to 4, it is understood that the steering stability performance of the tire is improved and the rolling resistance is reduced.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 21, 22 Circumferential main groove, 31 Center land part, 32 Shoulder land part, 41, 42 Lug groove, 11 Bead core, 12 Bead filler, 13 Carcass layer, 14 Belt layer, 141, 142 Cross belt, 143 Belt cover, 15 tread rubber, 16 side wall rubber, 17 rim cushion rubber

Claims (6)

A plurality of circumferential main grooves extending in the tire circumferential direction; a plurality of land portions defined by the circumferential main grooves; and the left and right land portions on the outermost sides in the tire width direction among the plurality of land portions (Hereinafter, referred to as a shoulder land portion) is a pneumatic tire provided with a plurality of lug grooves extending in the tire width direction,
The plurality of lug grooves are arranged in the tire circumferential direction in a predetermined arrangement pattern having a plurality of types of pitch lengths, and
Section in which radius constituting at least 60% of the profile line in region X from the tire ground contact edge to the tread edge has the minimum pitch length among the plurality of types of pitch lengths in a sectional view in the tire meridian direction A pneumatic tire characterized in that it is minimum at the maximum and maximum in the section having the maximum pitch length. The plurality of lug grooves are arranged in a tire circumferential direction in a predetermined arrangement pattern having at least three types of pitch lengths Pa, Pb, and Pc of small, medium, and large, and
The radius Ra of the section having the pitch length Pa to be small, the radius Rb of the section having the pitch length Pb to be medium, and the radius Rc of the section having the pitch length Pc to be large are Ra The pneumatic tire according to claim 1, which has a relationship of <Rb <Rc.   The pneumatic tire according to claim 1 or 2, wherein the profile line of a section having a maximum pitch length among the plurality of types of pitch lengths is a straight line.   4. The minimum pitch length Pmin and the maximum pitch length Pmax among the plurality of types of pitch lengths have a relationship of 1.3 ≦ Pmax / Pmin ≦ 1.8. Pneumatic tire described in 2.   The pneumatic tire according to any one of claims 1 to 4, wherein a ratio of a contact width of each portion of the shoulder land portion defined by the lug groove is in a range of 0.9 to 1.1. .   In a sectional view in the tire meridian direction, the cross-sectional area of each portion of the shoulder land portion defined by the lug groove is the largest in the section having the minimum pitch length, and the section having the maximum pitch length. The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is minimized.

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