JP2020075644A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can be improved in wet performance and anti-crack performance.SOLUTION: A pneumatic tire comprises circumferential main grooves 2 (2c and 2s) extending in a tire circumferential direction and protruding parts 5 (51 and 52) provided at groove walls of the circumferential main grooves 2 (2c and 2s) to extend in the tire circumferential direction and having flexibility in a tire radial direction. In a tire meridian cross section, a ratio Td/Ld of a thicknesses Td in the tire radial direction of the protruding parts 5 (51 and 52) to lengths Ld in a tire width direction of the protruding parts 5 (51 and 52) is 0.07 or more and 0.7 or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  When a pneumatic tire is used for a long period of time, cracks may occur and the appearance of the tire may deteriorate. A crack is a crack found on the surface of rubber. Cracks occur due to deterioration due to light, a small amount of ozone contained in the atmosphere, and deformation of rubber due to rolling of a tire.

  By the way, Patent Document 1 discloses a technique for preventing a crack in a groove. In the pneumatic tire disclosed in Patent Document 1, the protrusion is provided on the wall surface of the circumferential groove toward the other groove sidewall surface.

JP, 2005-263087, A

  If the protrusion of Patent Document 1 is provided, cracks in the groove can be reduced. However, regarding the shape of the protrusion, there is room for improvement in terms of wet performance and crack resistance performance.

  The present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire provided with a protrusion capable of improving wet performance and crack resistance performance.

  In order to solve the problems described above and achieve the object, a pneumatic tire according to an aspect of the present invention has a circumferential main groove extending in the tire circumferential direction, and a tire circumferential direction on a groove wall of the circumferential main groove. And a protrusion portion having flexibility in the tire radial direction, the tire radial direction thickness of the protrusion portion with respect to the tire width direction length Ld of the protrusion portion in a tire meridional section. The ratio Td / Ld of the thickness Td is 0.07 or more and 0.7 or less.

  The ratio Ld / W1 of the length Ld of the protruding portion in the tire width direction to the opening width W1 of the circumferential main groove is preferably 0.3 or more and 0.7 or less.

  The ratio H2 / H1 of the height H2 from the groove bottom to the protruding portion with respect to the groove depth H1 from the groove bottom to the opening position of the circumferential main groove is 0.38 or more and 0.88 or less. preferable.

  The angle of the protruding direction of the protruding portion with respect to the tire width direction is preferably within a range of ± 15 °.

  It is preferable that the protrusion is provided at least on the groove wall of the circumferential main groove arranged in the shoulder portion.

  The center portion and the shoulder portion of the tread portion are respectively provided with the circumferential main groove and the protruding portion, and the height of the protruding portion of the shoulder portion is larger than the height of the protruding portion of the center portion. Is preferred.

  The protrusions may be provided on groove walls on both sides in the tire width direction of the circumferential main groove.

  The ratio TLd / W1 of the total TLd of the length Ld of the protrusion in the tire width direction to the opening width W1 of the circumferential main groove is preferably 0.2 or more and 1.2 or less.

  It is preferable that the protrusion has at least one notch or notch in the middle of extending in the tire circumferential direction.

  According to the present invention, wet performance and crack resistance performance can be improved.

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 an enlarged meridional sectional view showing the circumferential main groove of FIG. 1. FIG. 3 is a meridional sectional view showing an enlarged projection portion. FIG. 4 is a meridional cross-sectional view illustrating the protrusion angle of the protrusion. FIG. 5: is a figure explaining the volume of the space from a protrusion part to a grounding surface. FIG. 6 is a diagram showing an example in which protrusions are provided on groove walls on both sides of the circumferential main groove in the tire width direction. FIG. 7 is a diagram showing a pneumatic tire having notches in the tire radial direction and having divided protrusions.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description of each embodiment, the same or equivalent components as those of the other embodiments are designated by the same reference numerals, and the description thereof will be simplified or omitted. The present invention is not limited to each embodiment. Further, the constituent elements of each embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. It should be noted that the plurality of modified examples described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art. Further, the configurations described below can be appropriately combined. Further, the configuration can be omitted, replaced, or changed without departing from the scope of the invention.

[Pneumatic tire]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a pneumatic tire 1 according to an embodiment of the present invention. The cross section in the tire meridian direction means a cross section when the tire is cut along a plane including the tire rotation axis (not shown). FIG. 1 shows a cross-sectional view of one side region of the pneumatic tire 1 in the tire radial direction. Further, FIG. 1 shows a radial tire for passenger cars as an example of the pneumatic tire 1.

  In the following description, the tire radial direction means a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial inner side means the side facing the rotation axis in the tire radial direction, the tire radial outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a circumferential direction with the rotation axis as the central axis. Further, the tire width direction means a direction parallel to the rotation axis, the tire width direction inner side is a side facing the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the tire width direction outer side is the tire width direction. In, 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 of the portions located outside in the tire width direction, that is, the distance between the portions most distant from the tire equatorial plane CL in the tire width direction. The tire equatorial line is a line on the tire equatorial plane CL and extending in the tire circumferential direction of the pneumatic tire 1. In the present embodiment, the tire equatorial line is designated by the same reference numeral “CL” as the tire equatorial plane.

  The pneumatic tire 1 has an annular structure centered on the tire rotation axis, and has a pair of bead cores 11 and 11, a pair of bead fillers 12 and 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. And a pair of sidewall rubbers 16 and 16 and a pair of rim cushion rubbers 17 and 17.

  The pair of bead cores 11 and 11 are annular members formed by bundling a plurality of bead wires, and form the cores of the left and right bead portions. The pair of bead fillers 12 and 12 are arranged on the outer circumferences of the pair of bead cores 11 and 11 in the tire radial direction to form a bead portion.

  The carcass layer 13 has a single-layer structure composed of one carcass ply or a multi-layered structure formed by laminating a plurality of carcass plies. The carcass layer 13 is bridged in a toroidal shape between the left and right bead cores 11 to form a tire skeleton. Constitute. Further, both ends of the carcass layer 13 are rolled back and locked to the outside in the tire width direction so as to surround the bead core 11 and the bead filler 12. The carcass ply of the carcass layer 13 is formed by coating 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 rolling it. It has a carcass angle of not less than [deg] and not more than 95 [deg] (tilt 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 a belt cover 143, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 are formed by coating a plurality of belt cords made of steel or an organic fiber material with coated rubber and rolling the belt cords, and have an absolute value of a belt angle of 20 [deg] or more and 55 [deg] or less. Have. The pair of intersecting belts 141 and 142 have belt angles (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction) of mutually different signs, and are laminated with the fiber directions of the belt cord intersecting each other. (Cross ply structure). The belt cover 143 is formed by rolling a plurality of cords made of steel or organic fiber material coated with coat rubber, and has a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. Further, the belt cover 143 is laminated and arranged on the outer side in the tire radial direction of the cross belts 141 and 142.

  The tread rubber 15 is arranged on the outer circumference of the carcass layer 13 and the belt layer 14 in the tire radial direction to form the tread portion 21 of the tire. The pair of sidewall rubbers 16, 16 are respectively arranged on the tire width direction outer side of the carcass layer 13 to form left and right sidewall portions. The pair of rim cushion rubbers 17, 17 are respectively arranged on the inner sides of the rewinding portions of the left and right bead cores 11, 11 and the carcass layer 13 in the tire radial direction so that contact surfaces of the left and right bead portions with respect to a rim flange (not shown) are formed. Constitute.

  The tread portion 21 has a plurality of (four in the present embodiment) circumferential main grooves 2 extending in the tire circumferential direction. The circumferential main groove 2 extends from the front side of the paper surface of FIG. 1 to the back side, that is, in the tire circumferential direction. The circumferential main groove 2 includes a circumferential main groove 2s provided in the shoulder portion and a circumferential main groove 2c provided in the center portion. In the following description, the circumferential main groove 2s and the circumferential main groove 2c may be collectively referred to as the circumferential main groove 2.

  The tread portion 21 is divided by the plurality of circumferential main grooves 2, extends along the tire circumferential direction, and has a plurality of land portions 4 (five in the present embodiment) arranged in the tire width direction. A protrusion 5 is provided on the groove wall of the circumferential main groove 2. The main groove is a groove that is required to display a wear indicator defined by JATMA.

  The shoulder portion is a portion on both outer sides in the tire width direction of the tread portion 21. The shoulder portion means each 1/4 range near the ground contact end when the tread portion 21 is divided into four in the tire width direction by applying a prescribed internal pressure and a prescribed load after assembling the tire rim. The center portion refers to the remaining half of the four tread portions that straddle the tire equatorial plane CL.

  The tread portion 21 is exposed on the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof becomes the contour of the pneumatic tire 1. A tread surface is formed on the outer peripheral surface of the tread portion 21, that is, on the tread surface that comes into contact with the road surface during traveling.

  FIG. 2 is a meridional sectional view showing the circumferential main groove 2 of FIG. 1 in an enlarged manner. A projecting portion 5 is provided on the groove wall of the circumferential main groove 2. The protruding portion 5 has flexibility in the tire radial direction, as indicated by a broken line 5h in FIG. That is, the free end side of the protruding portion 5 which is separated from the groove wall of the circumferential main groove 2 can be deformed to the tire radial inner side and the tire radial outer side.

  In this example, the protrusions 5 (51, 52) are provided on the groove walls on both sides of the circumferential main groove 2 in the tire width direction. The protruding portions 5 (51, 52) extend from the front side of the paper surface of FIG. 2 to the back side, that is, in the tire circumferential direction. The length of the protrusion 5 (51, 52) in the tire width direction is Ld (Ld1, Ld2).

(Aspect ratio of protrusion)
FIG. 3 is a meridional sectional view showing the protrusion 5 in an enlarged manner. The cross-sectional shape of the protrusion 5 shown in FIG. 3 is substantially triangular. In FIG. 3, the ratio Td / Ld of the thickness Td in the tire radial direction of the protrusion 5 to the length Ld (Ld1, Ld2) of the protrusion 5 in the tire width direction, that is, the aspect ratio is 0.07 or more 0.7 The following is preferable. When the aspect ratio of the protrusion 5 is in this range, the protrusion 5 is bent by water pressure when it comes in contact with the wet road surface. Since the protruding portion 5 bends due to the water pressure at the time of contact with the ground, the water infiltration into the circumferential main groove 2 and the drainage property can be adjusted, so that the wet performance equivalent to the case without the protruding portion can be realized. When the ratio Td / Ld is less than 0.07, the strength of the protrusion 5 is insufficient, which is not preferable. When the ratio Td / Ld exceeds 0.7, the flexibility of the protruding portion 5 in the tire radial direction becomes insufficient, which is not preferable. The ratio Td / Ld is more preferably 0.13 or more and 0.24 or less. The thickness Td is the maximum thickness of the protrusion 5 in the tire radial direction.

  The cross-sectional shape of the protrusion 5 is not limited to a substantially triangular shape, but may be a substantially rectangular shape or a substantially trapezoidal shape. It is preferable that the thickness of the protruding portion 5 (51) on the free end side of the circumferential main groove 2 away from the groove wall is the smallest. Even in the case of these cross-sectional shapes, the above aspect ratio is preferable.

(Length of protrusion with respect to main groove opening width)
Returning to FIG. 2, the ratio Ld / W1 of the length Ld (Ld1, Ld2) of the protruding portion 5 in the tire width direction to the opening width W1 of the circumferential main groove 2 is 0.3 or more and 0.7 or less. Is preferred. When the ratio Ld / W1 is in this range, it is possible to improve the crack resistance performance by maintaining the wet performance and adjusting the penetration amount of ozone and direct sunlight which are the main factors of the crack. If the ratio Ld / W1 is in the above range, air is less likely to stay and the groove bottom 2B is less likely to be exposed to new ozone, so that the crack resistance performance can be improved.

  If the ratio Ld / W1 is less than 0.3, ozone and direct sunlight cannot be sufficiently prevented from entering the groove bottom 2B, and it is difficult to improve the crack resistance, which is not preferable. When the ratio Ld / W1 exceeds 0.7, the drainage property deteriorates and it is difficult to improve the wet performance, which is not preferable.

(The height of the protrusion with respect to the groove depth of the main groove)
Depending on the position where the protrusions 5 (51, 52) are provided, the air column resonance sound when the pneumatic tire 1 touches the road surface may become loud. Therefore, the ratio H2 / H1 of the height H2 from the groove bottom to the protrusion 5 (51, 52) to the groove depth H1 from the groove bottom 2B of the circumferential main groove 2 to the opening position is 0.38 or more. It is preferably 0.88 or less. When the ratio H2 / H1 is within this range, the air column resonance noise that causes noise can be reduced, and noise performance can be improved.

  When the ratio H2 / H1 is less than 0.38 and when the ratio H2 / H1 exceeds 0.88, the air column resonance noise cannot be reduced, which is not preferable. The ratio H2 / H1 is more preferably 0.5 or more and 0.63 or less.

  The groove depth is measured as the maximum value of the distance from the tread surface to the groove bottom in an unloaded state in which the tire is mounted on the specified rim and filled with the specified internal pressure. Further, in a configuration in which the groove has a partial uneven portion or a sipe at the groove bottom, the groove depth is measured excluding these.

  The specified rim refers to “standard rim” specified by JATMA, “Design Rim” specified by TRA, or “Measuring Rim” specified by ETRTO. Further, the specified internal pressure means the maximum value of “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLOR INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. The specified load means the maximum value of "maximum load capacity" specified by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLOR INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO.

(Protrusion angle of protrusion)
FIG. 4 is a meridional cross-sectional view illustrating the protrusion angle of the protrusion. FIG. 4 is a meridional sectional view showing the circumferential main groove 2 of FIG. 1 in an enlarged manner. In FIG. 4, the angle θ1 is the angle in the protruding direction of the protruding portion 5 (51) with respect to the tire width direction. The angle θ1 is preferably 0 °, that is, parallel to the tire width direction. However, the angle θ1 may be within a range of ± 15 °. + 15 ° indicates that the free end of the protruding portion 5 (51) which is distant from the groove wall of the circumferential main groove 2 is inclined 15 ° outward in the tire radial direction. -15 ° indicates that the free end of the protruding portion 5 (51) which is distant from the groove wall of the circumferential main groove 2 is inclined 15 ° inward in the tire radial direction.

  When the angle θ1 of the projecting direction is within this range, the amount of ozone and direct sunlight entering the groove bottom 2B can be adjusted while maintaining the wet performance, and the crack resistance performance can be improved. When the angle θ1 is out of the range of ± 15 °, it is difficult to improve the crack resistance by adjusting the amount of ozone and direct sunlight entering the groove bottom 2B. Further, when the angle θ1 is a value within the above range, peeling from the mold is not hindered during vulcanization molding. The protruding direction of the protrusion 5 (51) is a direction connecting the midpoint of the thickness Td of the protrusion 5 (51) and the midpoint of the tip of the free end of the protrusion 5 (51). In FIG. 4, the direction of the alternate long and short dash line S4 is the protruding direction of the protruding portion 5 (51).

(Center part, shoulder part)
It is preferable that the protruding portion 5 is provided at least on the groove wall of the circumferential main groove 2s arranged in the shoulder portion. Since many cracks are generated in the circumferential main groove 2s of the shoulder portion, the effect of crack resistance performance is exhibited by providing the protrusion 5 at least in the circumferential main groove 2s of the shoulder portion.

  As shown in FIG. 1, when the center portion and the shoulder portion of the tread portion 21 are provided with the circumferential main grooves 2c and 2s, respectively, the protruding portions 5 (51, 52) of the circumferential main groove 2s of the shoulder portion are provided. It is preferable that the height H2 is larger than the height H2 of the protruding portions 5 (51, 52) of the circumferential main groove 2c of the center portion. Generally, the shoulder portion has a shorter ground contact length than the center portion. Therefore, by making the height H2 of the shoulder portion larger than the height H2 of the center portion, the volume of the space from the protruding portion 5 (51, 52) to the opening position of the circumferential main groove 2, that is, the ground contact surface It can be made smaller in the central part and larger in the central part.

  FIG. 5 is a diagram for explaining the volume of the space from the protruding portion 5 (51, 52) to the opening position of the circumferential main groove 2, that is, the ground contact surface. In FIG. 5, an imaginary line 5S connecting the tips of the protrusions 5 (51, 52) is assumed. The space S1 from the virtual line 5S to the opening position of the circumferential main groove 2, that is, the ground contact surface affects the air column resonance sound. As described above, the difference between the volume of the space S1 at the shoulder portion and the volume of the space S1 at the center portion can be increased, the air column resonance sound can be reduced, and the frequency of the passing sound can be changed.

(Groove walls on both sides)
The protrusions 5 may be provided on the groove walls on both sides of the circumferential main groove 2 in the tire width direction, respectively. FIG. 6 is a diagram showing an example in which the protrusions 51 and 52 are provided on the groove walls on both sides of the circumferential main groove 2 in the tire width direction. The height H21 of the protrusion 51 protruding from the groove wall 251 on the right side in FIG. 6 from the groove bottom 2B is different from the height H22 of the protrusion 52 protruding from the groove wall 252 on the left side from the groove bottom 2B. May be. Both the ratio H21 / H1 and the ratio H22 / H1 are preferably 0.38 or more and 0.88 or less, and more preferably 0.5 or more and 0.63 or less. The angle of the protruding portion 51 in the protruding direction and the angle of the protruding portion 52 in the protruding direction may be different or the same.

  When the protrusions 51 and 52 are provided on the groove walls 251 and 252 on both sides of the circumferential main groove 2 in the tire width direction, the length Ld1 of the protrusions 51 and 52 in the tire width direction with respect to the opening width W1 of the circumferential main groove. , Ld2, the total TLd ratio TLd / W1 is preferably 0.2 or more and 1.2 or less.

(Notch)
The protrusions 5 (51, 52) which are continuous in the tire circumferential direction are preferable for ensuring the rigidity thereof, but therefore, the metal for forming the circumferential groove 2 depending on the cross-sectional shape and the size of the cross-section. There is a possibility that the ease of release from the mold will deteriorate.

  Therefore, it is preferable to provide a cut in at least one location of the protrusion 5. The notch is a blank portion of the protrusion that interrupts the continuity of the protrusion. FIG. 7 is a diagram showing a pneumatic tire 1a having notches in the tire radial direction and having divided protrusions. FIG. 7 is a view of the pneumatic tire 1a viewed from the direction of the rotation axis (not shown).

  In the pneumatic tire 1a shown in FIG. 7, two notches 5c are provided in the tire radial direction on the side wall surface of the groove, and projecting portions 5a and 5b which are not divided into two but are divided into two are provided. By providing such a cut 5c, the pneumatic tire 1 can be easily removed from the mold, and productivity can be improved.

  If the protrusions 5 (51, 52) are continuous over the entire area in the tire circumferential direction, the protrusions 5 (51, 52) may be cut off when the tire is peeled from the mold after vulcanization. Therefore, it is possible to improve the workability by providing the cut 5c in at least one place of the protrusion 5 (51, 52). Even if such a cut 5c is provided, it is possible to reduce the noise from the tire during traveling due to the air column resonance noise, suppress the generation of cracks in the groove bottom 2B and the deterioration of wet performance.

  The protrusions 5a and 5b shown in FIG. 7 have a two-divided structure by providing the notch 5c, but the divided structure is not necessarily required. For example, instead of such a cut 5c, a cutout may be provided in at least one of the protrusions 5a and 5b. The notch is a portion in which the length of the protrusion in the tire width direction is shortened by removing a part of the protrusion from the free ends of the protrusions 5a and 5b. The notch is a portion where the continuity of the protrusion is not interrupted and the length of the protrusion in the tire width direction is short. Even when the notch is provided, the pneumatic tire 1 can be easily removed from the mold and the productivity can be improved. As described above, it is preferable that the protrusion 5 (51, 52) has at least one notch or notch in the middle of extending in the tire circumferential direction.

(Example)
In the examples, performance evaluation tests regarding wet performance (hydroplaning resistance) and crack resistance were performed on a plurality of types of pneumatic tires having different conditions.

  In the wet performance test, a pneumatic tire (test tire) having a tire size of 215 / 45R18 89W was mounted on a regular rim of 18 × 7.0J, filled with a regular internal pressure of 250 kPa, and mounted on a test vehicle having a displacement of 2000 cc. For the test vehicle, a running test was carried out so that the vehicle entered a pool with a water depth of 10 ± 1 mm on a straight road, and the entry speed into the pool was gradually increased, and the limit speed at which the hydroplaning phenomenon occurred was measured. The evaluation results are shown by an index with the conventional example being 100. The larger the index value, the better the hydroplaning resistance.

  For the crack resistance performance, the manufactured pneumatic tire (test tire) having a tire size of 215 / 45R18 89W was mounted on a regular rim of 18 × 7.0J and filled with a regular internal pressure of 250 kPa, and exposed outdoors to sufficient sunlight. After being left for 6 months, the test was conducted.

  Further, a pneumatic tire having no protrusion in the circumferential main groove was prepared as a conventional example. Furthermore, the aspect ratio Td / Ld is 1.2, the ratio of the opening width W1 of the main groove 2 to the length Ld of the protrusion 5 is 0.2, and the ratio H2 / H1 is 0.3. A pneumatic tire provided on a groove wall on one side of the circumferential main groove was prepared as a comparative example. In the examples shown in the tables, the aspect ratio Td / Ld, the ratio Ld / W1, the ratio H2 / H1 and the protrusions of the protrusions 5 on the groove walls on both sides of the circumferential main groove are shown. The angle of the protruding direction shows an average value.

  As shown in Tables 1 and 2, when the ratio Td / Ld is 0.07 or more and 0.7 or less, when the ratio Ld / W1 is 0.3 or more and 0.7 or less, the aspect ratio H2 / H1 is , 0.38 or more and 0.88 or less, when the protrusion direction angle of the protrusion 5 is within the range of ± 15 °, the length Ld of the protrusion 5 in the tire width direction with respect to the opening width W1 It can be seen that good results are obtained when the ratio TLd / W1 of the total TLd is 0.2 or more and 1.2 or less. In addition, there was no difference in the wet performance and the crack resistance performance with and without the notch or notch.

1, 1a Pneumatic tire 2, 2c, 2s Circumferential main groove 4 Land portion 5, 5a, 5b, 51, 52 Projection portion 5c Cut 11 Bead core 12 Bead filler 13 Carcass layer 14 Belt layer 15 Tread rubber 16 Sidewall rubber 17 Rim cushion rubber 21 Tread portion 251, 251 Groove wall CL Tire equatorial plane

Claims (9)

A circumferential main groove that extends in the tire circumferential direction, and a groove wall of the circumferential main groove that is provided to extend in the tire circumferential direction, and includes a protrusion having flexibility in the tire radial direction,
A pneumatic tire having a ratio Td / Ld of the thickness Td of the protrusion in the tire radial direction to the length Ld of the protrusion in the tire width direction in the tire meridional section is 0.07 or more and 0.7 or less. The pneumatic tire according to claim 1, wherein a ratio Ld / W1 of a length Ld of the protrusion in the tire width direction to an opening width W1 of the circumferential main groove is 0.3 or more and 0.7 or less. The ratio H2 / H1 of the height H2 from the groove bottom to the protruding portion with respect to the groove depth H1 from the groove bottom to the opening position of the circumferential main groove is 0.38 or more and 0.88 or less. The pneumatic tire according to claim 1 or claim 3.   The pneumatic tire according to any one of claims 1 to 3, wherein an angle of the protruding direction of the protruding portion with respect to a tire width direction is within a range of ± 15 °.   The pneumatic tire according to any one of claims 1 to 4, wherein the protruding portion is provided at least on a groove wall of the circumferential main groove arranged in the shoulder portion. The center part and the shoulder part of the tread part are each provided with the circumferential main groove and the protruding part,
The pneumatic tire according to any one of claims 1 to 5, wherein a height of the protruding portion of the shoulder portion is larger than a height of the protruding portion of the center portion.   The pneumatic tire according to any one of claims 1 to 6, wherein the projecting portions are provided on groove walls on both sides of the circumferential main groove in the tire width direction.   The pneumatic tire according to claim 7, wherein the ratio TLd / W1 of the total TLd of the length Ld of the protrusion in the tire width direction to the opening width W1 of the circumferential main groove is 0.2 or more and 1.2 or less. .   The pneumatic tire according to any one of claims 1 to 8, wherein the protrusion has at least one notch or notch in the middle of extending in the tire circumferential direction.

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