JP2012040891A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve water drainage performance of a pneumatic tire.SOLUTION: Straight grooves 2 (2A and 2B) extending in a tire circumferential direction T are provided in a tread of a tread section 1, and first lug grooves 3 which are branched from the straight grooves 2 are provided in the tread of the tread section 1. A projection section 5 is provided by projecting in a bending shape to a branch position side of the first lug groove 3 from a wall face 11b of the first straight groove 2A which faces the branch position of the first lug groove 3, and projections 6 are provided at a rear side in a tire rotation direction R, of the projection section 5.

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that improves drainage performance.

  In a pneumatic tire, it has been found that a tread pattern formed by main grooves and lug grooves has a great influence on steering stability and wear resistance. For example, if the arrangement of the main grooves and lug grooves is changed in order to improve the drainage performance of the tire, the steering stability and wear resistance also change.

  In the pneumatic tire described in Patent Document 1 below, a plurality of inclined grooves extending inclined from the circumferential groove toward the tread grounding end are disposed, and the inclined groove in the circumferential groove is opened. The drainage performance is improved by forming a pseudo land part in the corresponding part. Moreover, in the pneumatic tire of the following patent document 2, the lug groove branched from the straight groove is provided, and a protrusion protruding in a curved shape is provided on the opposite straight groove wall surface facing the branch position of the lug groove. The drainage performance is improved by providing a plurality in the circumferential direction.

Japanese Patent Laid-Open No. 2001-026205 JP 2004-196144 A

  In the pneumatic tire of Patent Document 1 described above, since a large step is formed on the rear side of the pseudo protrusion, a large vortex is generated immediately after the water flow flowing through the circumferential groove passes through the pseudo protrusion, and the water flow is separated. There is a problem that the water flow is resisted by this water flow separation and the improvement in drainage performance is diminished. Moreover, in the pneumatic tire of patent document 2, although the phenomenon of water flow separation can be suppressed, a water flow is easy to peel immediately after the downstream of a protrusion, and the further drainage performance improvement is calculated | required.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve drainage performance.

  In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention has a straight groove extending in the tire circumferential direction on the tread surface and a branch from the straight groove on the tread surface. A lug groove, a protrusion protruding in a curved shape from the wall surface of the straight groove facing the branch position of the lug groove toward the branch position side of the lug groove, and provided on the rear side of the protrusion in the tire rotation direction And an uneven portion to be provided.

  According to this pneumatic tire, a part of the water flow in the straight groove can be smoothly diverted to the lug groove side by the protrusion while smoothing the water flow in the straight groove. Water flow separation can be prevented by minimizing the vortex generated on the downstream side of the section, and as a result, drainage performance can be improved.

  Further, in the pneumatic tire of the present invention, the protrusion has a top portion that protrudes most from the wall surface of the straight groove to the branch position side of the lug groove, and the uneven portion is formed on the surface of the protrusion. It is provided on the rear side in the tire rotation direction from the top.

  According to this pneumatic tire, by providing the uneven portion on the rear side from the top on the surface of the protrusion, a part of the water flow in the straight groove can be smoothly diverted to the lug groove side, and the protrusion of the protrusion The vortex generated on the wake side can be minimized.

  In the pneumatic tire according to the present invention, the protrusion has a concave shape on the front side in the tire rotation direction from the top.

  According to this pneumatic tire, a part of the water flow in the straight groove can be smoothly diverted to the lug groove side by the front surface of the protrusion.

  In the pneumatic tire according to the present invention, the protrusion has a convex shape on the rear side in the tire rotation direction from the top.

  According to this pneumatic tire, the water flow in the straight groove can be made to flow smoothly by the surface on the rear side of the protrusion.

  In the pneumatic tire of the present invention, the protrusion has a cross-sectional area parallel to the tread surface that decreases from the bottom of the straight groove toward the opening.

  According to this pneumatic tire, by reducing the protrusion from the groove bottom to the opening side, resistance generated in the water flow flowing in the straight groove can be reduced, and the water flow in the straight groove can flow smoothly.

  In the pneumatic tire of the present invention, the uneven portion has a plurality of concave portions or a plurality of convex portions, and the concave portion or the convex portions have a hemispherical shape or a pyramid shape.

  According to this pneumatic tire, the vortex generated on the downstream side of the protrusion can be minimized as much as possible by forming the concave portion or the convex portion into a hemispherical shape or a pyramid shape.

  In the pneumatic tire according to the present invention, the density of the concave portion or the convex portion increases toward the rear side in the tire rotation direction.

  According to this pneumatic tire, the vortex generated on the wake side of the protruding portion can be effectively reduced by the concave portion or the convex portion, and the water flow in the straight groove can be smoothly flowed by appropriately preventing water flow separation. be able to.

  Further, in the pneumatic tire of the present invention, the tire circumferential direction length from the front end in the tire rotation direction at the protrusion to the branch start position of the lug groove is set in a range of 5 mm to 15 mm. Features.

  According to this pneumatic tire, a part of the water flow in the straight groove can be smoothly diverted to the lug groove side by the protrusion at an appropriate position.

  The pneumatic tire according to the present invention is characterized in that the protruding portion has a length in the width direction of the straight groove set in a range of 5% to 30% of the width of the straight groove.

  According to this pneumatic tire, a part of the water flow in the straight groove can be smoothly diverted to the lug groove side by the protrusion, and the vortex generated on the downstream side of the protrusion can be effectively reduced. Thus, the resistance of the water flow flowing in the straight groove can be reduced.

  In the pneumatic tire of the present invention, the length of the protrusion in the longitudinal direction of the straight groove is set in a range of 100% to 200% of the width of the straight groove.

  According to this pneumatic tire, a part of the water flow in the straight groove can be smoothly diverted to the lug groove side by the protrusion, and the vortex generated on the downstream side of the protrusion can be effectively reduced. Thus, the resistance of the water flow flowing in the straight groove can be reduced.

  In the pneumatic tire according to the present invention, the protrusion is provided on the wall surface of the straight groove facing the branching position of the lug groove, and the uneven portion is provided on the rear side of the protrusion, so that the drainage performance can be improved. .

FIG. 1 is a developed plan view showing a part of a tread portion in a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a front view showing the protrusion. FIG. 3 is a perspective view showing a protrusion. FIG. 4 is a cross-sectional view showing a protrusion. FIG. 5 is a perspective view showing a modification of the protrusion. FIG. 6 is a cross-sectional view showing another modification of the protrusion. FIG. 7 is a cross-sectional view showing another modification of the protrusion. FIG. 8 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

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

  In the following description, the tire circumferential direction is a circumferential direction with the rotation axis of the pneumatic tire as the central axis. The tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction is the side toward the tire equatorial plane in the tire width direction, and the outer side in the tire width direction is the tire equatorial plane in the tire width direction. It is the side away from. Further, the tire radial direction means a direction orthogonal to the rotation axis, the tire radial direction inner side is a side toward the rotation axis in the tire radial direction, and the tire radial direction outer side is separated from the rotation axis in the tire radial direction. On the side. The tire equator plane is a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire.

  In the pneumatic tire of the present embodiment, as shown in FIG. 1, reference numeral 1 represents a tread portion in which the tire rotation direction R is designated as one direction, and the tread portion 1 is on the surface (tread surface). Four straight grooves 2 extending along the tire circumferential direction T are provided. The four straight grooves 2 are disposed symmetrically in the tire width direction W with respect to the tire equatorial plane CL of the tread portion 1 and are paired with a pair of first straight grooves 2A adjacent to the tire equatorial plane CL. And a pair of second straight grooves 2B adjacent to the tire ground contact edge E.

  Further, the tread portion 1 includes a plurality of first lug grooves 3 branched from the first straight grooves 2A and extending toward the tire ground contact end E side on the left and right in the tire width direction W with respect to the tire equatorial plane CL. They are arranged symmetrically. The first lug grooves 3 extend outward in the tire width direction while inclining from the first straight grooves 2A toward the tire rotation direction R (tire counter-rotation direction), and intersect the second straight grooves 2B. Are connected to the tire ground contact edge E, and are arranged at predetermined intervals along the tire circumferential direction T.

  Further, in the tread portion 1, a plurality of second lug grooves 4 branched from the second straight groove 2 </ b> B and extending to the tire ground contact end E side are symmetrical in the tire width direction W with respect to the tire equatorial plane CL. Are arranged. The second lug grooves 4 extend outward in the tire width direction from the respective second straight grooves 2B, and extend to the front without being communicated with the tire ground contact edge E while being inclined in the same direction as the first lug grooves 3. And are provided at predetermined intervals along the tire circumferential direction T.

  The first lug grooves 3 and the second lug grooves 4 are alternately arranged in the tire circumferential direction T.

  In the pneumatic tire of the present embodiment configured as described above, from the wall surface on the opposite side of the first straight groove 2 </ b> A facing the branch position of the first lug groove 3 to the branch position side of the first lug groove 3. A protruding portion 5 that protrudes in a curved shape is provided. The protrusion 5 swells in a curved shape in plan view perpendicular to the tread surface. That is, the protrusion 5 is formed to have a curved surface in a plan view as viewed perpendicular to the tread surface, and has the same plan view shape in the groove depth direction of the first straight groove 2A. It has a columnar shape and can maintain almost the same performance even when the tire is worn.

  That is, as shown in FIGS. 2 to 4, the first straight groove 2 </ b> A includes a bottom portion 11 a that is substantially parallel to the trad surface and a first inclination groove that is located on the tire equatorial plane CL side and rises at a predetermined inclination angle with respect to the bottom portion 11 a. 1 wall surface 11b and the 2nd wall surface 11c which is located in the tire grounding edge E (refer FIG. 1) side, and stands | starts up with the predetermined | prescribed inclination angle with respect to the bottom part 11a. In this case, the first wall surface 11b and the second wall surface 11c are substantially symmetrical with respect to the bottom portion 11a.

  The first lug groove 3 is branched from the second wall surface 11 c side of the first straight groove 2 </ b> A, and this position is the branch position of the first lug groove 3. The protrusion 5 extends from the first wall surface 11b of the first straight groove 2A facing the tire width direction (the width direction of the first straight groove 2A) W to the branch position of the first lug groove 3 from the first lug. It protrudes to the branch position side of the groove 3, that is, the second wall surface 11c of the first straight groove 2A.

  In this case, the protruding portion 5 is provided with a top portion 21a that protrudes most from the first wall surface 11b of the first straight groove 2A toward the branching position side of the first lug groove 3 and has a curved shape. And this projection part 5 is provided with the 1st curved part 21b which makes a concave curved shape in the front side of the tire rotation direction R from the top part 21a. Further, the protruding portion 5 is provided with a second curved portion 21c having a convex curved shape on the rear side in the tire rotation direction R from the top portion 21a.

  Then, the protrusion 5 has the first curved portion 21b and the second curved portion 21c smoothly connected to the first wall surface 11b of the first straight groove 2A without any step, and the first curved portion. The other end portions of 21b and the second bending portion 21c are smoothly continuous with one end portion and the other end portion of the top portion 21a. The protrusion 5 has a predetermined inclination with respect to the bottom 11a so that the surfaces (the top 21a, the first curved portion 21b, and the second curved portion 21c) are parallel to the first wall surface 11b of the first straight groove 2A. It is set to an angle.

  Further, in the pneumatic tire of the present embodiment, a plurality of convex portions (concave / convex portions) 6 are provided on the rear side in the tire rotation direction R of the protruding portion 5. The convex portion 6 is provided so as to protrude from the top portion 21a on the surface of the projection portion 5 to the rear side in the tire rotation direction R, that is, from the second curved portion 21c to the second wall surface 11c side of the first straight groove 2A. Yes.

  The plurality of convex portions 6 have a hemispherical shape, and are arranged so as to be aligned along the longitudinal direction of the first straight groove 2A and aligned along the depth direction of the first straight groove 2A. . In this case, each convex part 6 does not need to be a perfect hemispherical shape, and should just protrude from the surface of the 2nd curved part 21c so that a spherical surface may be made.

  Here, an ideal formation position and size of the protrusion 5 will be described. As shown in FIG. 2, the protrusion 5 has a length (from the front end in the tire rotation direction R to the branch start position of the first lug groove 3 in the direction along the longitudinal direction of the first straight groove 2 </ b> A ( The tire circumferential length) D is preferably set in the range of 5 mm to 15 mm. In this case, when the tire circumferential direction length D of the protrusion 5 is set in the range of 5 mm to 15 mm, a part of the water flow in the first straight groove 2A is smoothly diverted to the first lug groove 3 side by the protrusion 5. be able to.

  Moreover, it is preferable that the protrusion part 5 sets the width direction length W2 of 2 A of 1st straight grooves to the range of 10%-30% of the width W 1 of 2 A of 1st straight grooves. Moreover, it is preferable that the protrusion part 5 sets the longitudinal direction length L of 2 A of 1st straight grooves to the range of 100%-200% of the width W1 of 2 A of 1st straight grooves. Specifically, it is preferable to set the width direction length W2 of the protruding portion 5 to a range of 1.0 to 3.0 mm. Moreover, it is preferable that the protrusion part 5 sets the longitudinal direction length L to the range of 10.0-20.0 mm. Further, the protrusion 5 has a length L1 from the front end in the tire rotation direction R to the top 21a (the length of the first curved portion 21b) L1 in the longitudinal direction of the first straight groove 2A, and the tire from the top 21a. It is preferable to set 2L1 <L2 in relation to the length to the rear end in the rotation direction R (the length of the second bending portion 21c) L2.

  In this case, by setting the widthwise length W2 of the protrusion 5 within the above-described range, a part of the water flow in the first straight groove 2A can be smoothly diverted to the first lug groove 3 side, The resistance of the water flow flowing through the first straight groove 2A can be reduced. Similarly, by setting the length L in the longitudinal direction of the protrusion 5 in the above-described range, a part of the water flow in the first straight groove 2A can be smoothly diverted to the first lug groove 3 side. At the same time, the resistance of the water flow flowing in the first straight groove 2A can be reduced.

  Accordingly, when the vehicle travels on a wet road surface, when the water flow moves in the first anti-rotation direction in the first straight groove 2A, it is deflected by the action of the protruding portion 5 at the branching point of the first lug groove 3, Since the part is smoothly drifted toward the first lug groove 3, the drainage performance is improved. In addition, the water flow that has traveled over the protrusion 5 toward the first straight groove 2 </ b> A generates a vortex on the downstream side of the protrusion 5. However, since the curved portions 21b and 21c are formed on the protruding portion 5 and the plurality of convex portions 6 are provided, the vortex is subdivided into small pieces, and the water flow is separated from the wall surface 11b of the first straight groove 2A. It becomes difficult and resistance to water flow becomes small. In this case, the drainage performance can be improved without substantially changing the basic tread pattern, and can be achieved without substantially affecting other tire performances.

  Moreover, the shape of the protrusion part 5 and the convex part 6 of this invention is not limited to embodiment mentioned above. For example, as shown in FIG. 5, the projection 31 is provided with a first curved portion 32 b having a concave curved shape on the front side in the tire rotation direction R from the top 32 a, as in the above-described projection 5. A second curved portion 32c having a convex curved shape is provided on the rear side in the tire rotation direction R from 32a. And the protrusion part 31 is provided with the some convex part 33 which protrudes from the 2nd curved part 32c. The plurality of convex portions 33 have a hemispherical shape, and are arranged so as to be shifted in the height direction (the depth direction of the first straight groove 2A) with respect to the longitudinal direction (the longitudinal direction of the first straight groove 2A). .

  In addition, each convex part 6 and 33 is not limited to hemispherical shape, It is good also as a pyramid shape, a truncated cone shape, a truncated pyramid shape, etc. Moreover, each convex part 6 and 33 is not limited to each arrangement | positioning mentioned above, You may arrange | position with a predetermined arrangement | sequence form, and may provide it at random.

  As shown in FIGS. 6 and 7, the protrusion 41 has a first straight groove that is opposed to the branch position of the first lug groove 3 (see FIG. 1) in the width direction of the first straight groove 2 </ b> A. It is provided so as to protrude in a curved shape from the first wall surface 11b of 2A to the branch position side of the first lug groove 3, that is, to the second wall surface 11c of the first straight groove 2A.

  The protruding portion 41 is provided with a top portion 42a that protrudes most from the first wall surface 11b of the first straight groove 2A toward the branching position side of the first lug groove 3 to form a curved shape, and the tire rotation direction R from the top portion 42a. A first curved portion 42b having a concave curved shape is provided on the front side, and a second curved portion 42c having a convex curved shape is provided on the rear side in the tire rotation direction R from the top portion 42a.

  And as for the projection part 41, the surface (the top part 42a, the 1st curved part 42b, the 2nd curved part 42c) is the upper part with respect to the 1st wall surface 11b of the 1st straight groove 2A, ie, the opening part of the 1st straight groove 2A It is set to be inclined and curved with respect to the bottom portion 11a so that the side approaches the first wall surface 11b side. That is, the protrusion 41 is set so that the cross-sectional area parallel to the tread surface decreases from the bottom 11a of the first straight groove 2A toward the opening.

  In addition, the protrusion 41 is provided with a plurality of protrusions (uneven portions) 43 on the rear side in the tire rotation direction R, that is, on the second curved portion 42c. The plurality of convex portions 43 are provided so as to protrude from the second curved portion 42c to the second wall surface 11c side of the first straight groove 2A, and have a hemispherical shape. And the some convex part 43 is set so that the presence density may increase toward the back side (right side in FIG. 7) of the tire rotation direction R. As shown in FIG.

  In the present embodiment, the size (surface area) of each protrusion 43 is substantially the same, and the number (number per predetermined area) increases on the rear side (right side in FIG. 7) in the tire rotation direction R. Like to do. In this case, by changing the size (surface area) and the number (number per predetermined area) of each convex portion 43, the existence density may be set to increase, but the rear side of the tire rotation direction R ( The right side in FIG. 7 is preferably set to increase the existence density by decreasing the size (surface area) of each convex portion 43 and increasing the number (number per predetermined area). .

  In addition, although the convex part 6,33,43 was provided as an uneven | corrugated | grooved part provided in the projection part of this invention, it is good also as a recessed part, and the arrangement | positioning should just be carried out similarly to the convex part 6,33,43.

  As described above, in the pneumatic tire according to the present embodiment, the straight groove 2 (2A, 2B) extending in the tire circumferential direction T is provided on the tread surface of the tread portion 1, and the straight groove is formed on the tread surface of the tread portion 1. The first lug groove 3 branched from 2 is provided, and protrudes in a curved shape from the wall surface 11b of the first straight groove 2A facing the branch position of the first lug groove 3 to the branch position side of the first lug groove 3. The protrusion 5 (31, 41) is provided, and the protrusion 6 (33, 43) is provided on the rear side in the tire rotation direction R of the protrusion 5 (31, 41).

  Therefore, a part of the water flow in the first straight groove 2A can be smoothly diverted to the first lug groove 3 side by the projection 5 while maintaining the water flow in the first straight groove 2A smoothly. At this time, by reducing the vortex generated on the downstream side of the protrusion 5 by the convex portion 6 as much as possible, water flow separation can be prevented, and as a result, drainage performance can be improved.

  In this case, the protrusion 5 (31, 41) is provided with a top 21a that protrudes most from the first wall surface 11b of the first straight groove 2A to the branch position side of the first lug groove 3, and the protrusion 6 (33, 43). ) Is provided on the rear side in the tire rotation direction R from the top portion 21 a on the surface of the protrusion 5. Therefore, a part of the water flow in the first straight groove 2A can be smoothly diverted to the first lug groove 3 side, and the vortex generated on the downstream side of the protrusion 5 can be minimized.

  Further, in the pneumatic tire of the present embodiment, the protrusion 5 (31, 41) is provided with a first curved portion 21b having a concave shape on the front side in the tire rotation direction R from the top 21a, and the tire rotates from the top 21a. A second curved portion 21 c having a convex shape is provided on the rear side in the direction R. Therefore, a part of the water flow in the first straight groove 2A can be smoothly diverted to the first lug groove 3 side by the first curved portion 21b, and the water flow in the first straight groove 2A can be diverted by the second curved portion 21c. It can flow smoothly.

  Further, in the pneumatic tire of the present embodiment, the protrusion 41 is set so that the cross-sectional area parallel to the tread surface decreases from the bottom 11a of the first straight groove 2A toward the opening. Therefore, the resistance generated in the water flow flowing in the first straight groove 2A can be reduced, and the water flow in the first straight groove 2A can flow smoothly.

  Moreover, in the pneumatic tire of this Embodiment, the convex part 6 (33, 43) is made into hemispherical shape or a pyramid shape. Therefore, the vortex generated on the downstream side of the protrusion 5 (31, 41) can be minimized.

  In the pneumatic tire of the present embodiment, the existence density is increased toward the rear side in the tire rotation direction R at the convex portion 43. Accordingly, the vortex generated on the downstream side of the protrusion 41 by the protrusion 43 can be effectively reduced, and the water flow in the first straight groove 2A can be smoothly flowed by appropriately preventing water flow separation. .

  Moreover, in the pneumatic tire of the present embodiment, the tire circumferential direction length D from the front end in the tire rotation direction R of the protrusion 5 to the branch start position of the first lug groove 3 is in the range of 5 mm to 15 mm. Is set. Therefore, a part of the water flow in the first straight groove 2A can be smoothly diverted to the first lug groove 3 side by the protrusion 5 at the appropriate position.

  Further, in the pneumatic tire of the present embodiment, the width direction length W2 of the first straight groove 2A is set to a range of 10% to 30% of the width W1 of the first straight groove 2A, and the first straight groove The longitudinal length L of 2A is set in the range of 100% to 200% of the width W1 of the first straight groove 2A. Accordingly, a part of the water flow in the first straight groove 2A can be smoothly diverted to the first lug groove 3 side by the protrusion 5, and the vortex generated on the downstream side of the protrusion 5 can be effectively reduced. It is possible to reduce the resistance of the water flow flowing in the first straight groove 2A.

  FIG. 8 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. In the present embodiment, a performance test regarding drainage performance was performed on a plurality of types of pneumatic tires having different conditions.

  In this performance test, a pneumatic tire with a tire size of 205 / 55R16 91V is assembled to a normal rim, filled with 95% of the normal internal pressure, 97% of the normal load is applied, and the front steering of a 2-D / 4 test vehicle is performed. The test was carried out with the shaft attached. The regular rim here refers to “standard rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. The normal internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO.

  The evaluation method is a test vehicle equipped with pneumatic tires. When traveling at a constant speed in a hydro pool with a water depth of 8 mm, the speed is increased from a low speed stepwise. Measure the speed when generated and evaluate drainage performance. The evaluation result is indicated by a performance index with the evaluation result of Conventional Example 1 being 100, and the larger the performance index (the above value), the better the drainage performance.

  In FIG. 8, the pneumatic tire of Conventional Example 1 has no protrusion at the branch position of the lug groove in the straight groove, and the pneumatic tire of Conventional Example 2 is at the branch position of the lug groove in the straight groove. The pneumatic tire of Conventional Example 3 has a triangular protrusion, and has a curved protrusion at the branching position of the lug groove in the straight groove. There is no uneven part in the part. On the other hand, the pneumatic tire of the example has a protruding portion having a curved shape at a branch position of the lug groove in the straight groove, and has an uneven portion on the protruding portion.

  As is clear from the table in FIG. 8, the pneumatic tires of Examples 1 to 8 have protrusions and irregularities, and each condition is optimized, so that drainage performance is improved. You can see that

  As described above, the pneumatic tire according to the present invention is suitable for a pneumatic tire that improves drainage performance.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Straight groove 2A 1st straight groove 2B 2nd straight groove 3 1st lug groove 4 2nd lug groove 5,31,41 Projection part 6,33,43 Convex part (concavo-convex part)
21a, 32a, 42a Top portion 21b, 32b, 42b First bending portion 21c, 32c, 42c Second bending portion

Claims (10)

Straight grooves extending in the tire circumferential direction on the tread surface,
A lug groove branched from the straight groove on the tread surface;
A protrusion protruding in a curved shape from the wall surface of the straight groove facing the branch position of the lug groove to the branch position side of the lug groove;
An uneven portion provided on the rear side in the tire rotation direction of the protrusion,
A pneumatic tire characterized by comprising:   The protruding portion has a top portion that protrudes most from the wall surface of the straight groove toward the branching position side of the lug groove, and the uneven portion is provided on the rear side in the tire rotation direction from the top portion on the surface of the protruding portion. The pneumatic tire according to claim 1, wherein   The pneumatic tire according to claim 2, wherein the protrusion has a concave shape on the front side in the tire rotation direction from the top.   The pneumatic tire according to claim 2, wherein the protrusion has a convex shape on the rear side in the tire rotation direction from the top.   The pneumatic tire according to any one of claims 1 to 4, wherein the protrusion has a cross-sectional area that is parallel to a tread surface that decreases from the bottom of the straight groove toward the opening.   The said uneven | corrugated | grooved part has a some recessed part or a some convex part, and the said recessed part or the said convex part makes hemispherical shape or a pyramid shape, It is any one of Claim 1 to 5 characterized by the above-mentioned. Pneumatic tire.   The pneumatic tire according to claim 6, wherein the existence density of the concave portion or the convex portion increases toward the rear side in the tire rotation direction.   The tire circumferential direction length from the front side edge part of the tire rotation direction in the protrusion to the branch start position of the lug groove is set in a range of 5 mm to 15 mm. A pneumatic tire according to any one of the above.   The air according to any one of claims 1 to 8, wherein the protruding portion has a length in a width direction of the straight groove set in a range of 10% to 30% of a width of the straight groove. Enter tire.   9. The projection according to claim 1, wherein a length of the straight groove in a longitudinal direction is set in a range of 100% to 200% of a width of the straight groove. Pneumatic tire.

Images