JP5519176B2 - Pneumatic tire - Google Patents

Description

  The present invention provides a plurality of block land by disposing a plurality of tire circumferential grooves extending in the tire circumferential direction and a plurality of lateral grooves communicating with two adjacent tire circumferential grooves in the tread portion. The present invention relates to a pneumatic tire in which a plurality of block land portion rows made up of sections are defined.

  In general, in a pneumatic tire having a tread pattern in which block land portions are arranged in the entire tread portion, uneven wear due to heel and toe wear occurring during traveling in proportion to a load applied is likely to occur. Here, heel and toe wear is the amount of wear between the stepping-in end (first grounding part) and the kicking-out end (final grounding part) due to excessive deformation of the block land during tire load rolling. This refers to wear that increases. Therefore, especially in heavy-duty pneumatic tires, uneven wear due to this heel and toe wear causes a wear difference mainly between the central portion of the block land and both ends in the tire circumferential direction, resulting in a short tire service life. There is a problem of becoming.

  Many countermeasures have been tried as countermeasures against such uneven wear. And among them, for example, as disclosed in Patent Document 1, a part of the lateral groove that defines the block is made shallower, that is, by providing a bottom raised portion in the lateral groove, the block land portion in the tire circumferential direction is provided. It is said that it is effective to increase stress against the falling deformation to suppress an increase in driving force load per unit area and prevent uneven wear due to the falling deformation.

  Here, in a heavy-duty pneumatic tire or the like having a large tire flatness ratio and high belt rigidity, as shown in FIG. 1, the tread that is in contact with the rotation of the belt portion when the driving force is applied and the road surface is grounded. Due to the friction of the portion, a displacement difference is generated between the belt portion and the tread portion, and the tread portion falls excessively and deforms (see the dotted line in FIG. 1). As a result, since the driving force burden per unit area of the tread portion increases, a slip phenomenon occurs on the road surface of the block land portion, and the wear amount of the block land portion increases due to the slip phenomenon. However, in the pneumatic tire described in Patent Document 1, although there is a certain effect in preventing uneven wear, it is not possible to sufficiently suppress the collapse deformation of the block land portion at the time of tire load rolling. It is not possible to suppress an increase in the amount of wear in the block land due to the above. Therefore, the pneumatic tire described in Patent Document 1 still has a problem in terms of wear resistance. In general, it is possible to effectively reduce the amount of wear of the block land portion by increasing the rigidity of the rubber constituting the block land portion and suppressing excessive falling deformation of the block land portion. If the rigidity of the part is excessively increased, the block land part may be destroyed by baldness or cracks when rolling the tire. Therefore, there is a need for a pneumatic tire that has improved uneven wear resistance and wear resistance without deteriorating steering stability and drainage performance by optimizing the shape of the block land portion and the arrangement position thereof. .

JP-A-6-171318

  On the other hand, by arranging a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of lateral grooves communicating two adjacent circumferential grooves, a plurality of block land portions are formed. In the pneumatic tire in which the block land portion row is partitioned, the length of the cross section of the block land portion in the tire width direction is determined by at least two block land portion rows adjacent to each other across the circumferential groove. The block land portions that are increased from the center to the center portion of the block land portion, and the block land portions constituting the two adjacent block land portion rows are shifted from each other in the tire circumferential direction and are adjacent to each other in the tire width direction The extending direction of the groove portion is inclined with respect to the tire width direction and the tire circumferential direction so that the distance between the block land portions adjacent in the tire width direction is shorter than the distance between the block land portions adjacent in the tire circumferential direction. Accordingly, it is conceivable to optimize the shape and arrangement position of the block land portion.

  If the block land portion having such a shape and position is used, for example, as shown in FIG. 2, when the block land portion 4 is grounded obliquely with respect to the road surface, a compressive stress is applied to the central region of the block land portion 4. Even if the force concentrates and the rubber in the central region of the block land portion 4 is deformed from the kicking end toward the stepping end, the tire circumferential direction on the kicking end side of the block land portion 4 is affected. Since a force (arrow Q in FIG. 2) is generated to cause the wall portion of the inclined block land portion 4 to swell in the normal direction, the component force R is offset in the block land portion 4. Further, the other component force P resists the force that the rubber in the central region of the block land portion 4 tries to deform from the kicking end toward the stepping end. Therefore, in the pneumatic tire described above, excessive deformation of the block land portion can be suppressed without deteriorating steering stability and drainage, and uneven wear and sliding wear of the block land portion can be prevented.

  However, if the rubber in the central region of the block land portion is increased in force against the force that tends to deform from the kicking end toward the stepping end, the occurrence of uneven wear is more effectively prevented. There was room for improvement in that it could be prevented.

An object of the present invention is to advantageously solve the above-described problems. In the pneumatic tire of the present invention, the opening edge of each groove wall extends in a zigzag shape along the tire circumferential direction in the tread portion. A pair of circumferentially thick grooves are disposed across the tire equator, the tread portion is divided into a central region and both lateral regions, and at least one zigzag extending along the tire circumferential direction in the central region And a plurality of transverse grooves extending between the circumferential thick grooves and the circumferential narrow grooves and / or between two adjacent circumferential narrow grooves, are located in the central region. The land portion is partitioned into at least two rows of central block land portions, each having a plurality of block land portions having an n-gonal shape (where n ≧ 6) in plan view, and the plurality of central block land portions Located in two adjacent central block land sections of the row The block land portions are in a positional relationship shifted from each other in the tire circumferential direction, and the block land portions located in the central block land portion row have tire cross-section lengths from both ends in the tire circumferential direction of the block land portions. The distance between the block land portions adjacent to each other in the tire width direction is shorter than the distance between the block land portions adjacent to each other in the tire circumferential direction. The block land portion located in the central block land portion row adjacent to the block land portion has an angle formed by the side wall angle of the adjacent circumferential thick groove side with the tread surface of the block land portion adjacent to the circumferential thick groove. small in the tire circumferential ends of the parts, at the center rather greater than the tire circumferential ends, the peripheral block land portions located adjacent each other across the direction thick groove is coordinating the tire circumferential direction position matches with each other The circumferential thick groove has a bellows shape in which the groove opening shape is formed by connecting a plurality of trapezoidal openings along the tire circumferential direction by alternately turning over the upper base and the lower base, and The groove bottom center position of the circumferential thick groove has a shape extending linearly in the tire circumferential direction . According to the pneumatic tire having such a configuration, the circumferentially thick grooves and the circumferentially narrow grooves extend in a zigzag shape in the tire circumferential direction, and the land portion located in the central region is an n-square shape in plan view (however, n ≧ 6), so that when the block land portion is grounded obliquely with respect to the road surface, the compressive stress is concentrated in the central region of the block land portion and the central region of the block land portion Even if the rubber is deformed from the kicking end toward the stepping-on end, a force is generated to cause the side wall on the kicking end side of the block land portion to bulge in the normal direction. Therefore, excessive deformation of the block land portion can be suppressed without deteriorating steering stability and drainage, and uneven wear and sliding wear of the block land portion can be prevented. Further, the tire of the block land portion is formed by making the side wall angle of the block land portion located in the central block land portion row adjacent to the circumferential thick groove an intersection angle with the tread surface of the block land portion adjacent to the circumferential groove. Since it is smaller at both ends in the circumferential direction and larger than both ends in the tire circumferential direction at the center, the area of the side wall on the kicking end side of the block land portion is increased, and the force that the side wall swells in the normal direction is large Become. Therefore, the occurrence of uneven wear can be more effectively prevented.
In the present invention, the “tread surface” refers to a surface that is in contact with the road surface during traveling, the “narrow groove” is a groove having a groove width smaller than the thick groove, and the “deviation positional relationship” is the tire width. This refers to a positional relationship in which the tire circumferential direction positions of the block land portions adjacent to each other in the direction are made different so that the tire circumferential ends of the block land portions do not coincide between the block land portions adjacent to each other in the tire width direction. Further, when the number of circumferential narrow grooves is one, there is no lateral groove extending between the circumferential narrow grooves.

Further, as described above , the positions of the block land portions adjacent to each other in the tire width direction across the circumferential thick groove are made the same, that is, between the block land portions adjacent to each other in the tire width direction. If the ends in the circumferential direction are matched, the drainage performance when traveling on the WET road surface can be improved . In addition, since the timing of stepping and kicking out the block land portion is the same in the tire width direction, stability during straight traveling can be increased .

Furthermore, as described above , the groove opening shape of the circumferentially thick groove is a bellows shape, and the groove bottom center position extends linearly, thereby further improving the drainage performance when traveling on the WET road surface. I can . In the present invention, the “groove bottom center position” refers to the center position in the tire width direction of the bottom surface of the groove.

Further, in the pneumatic tire of the present invention, the tread portion is provided with a pair of circumferential thick grooves in which the opening edge of each groove wall extends in a zigzag shape along the tire circumferential direction with the tire equator interposed therebetween, The tread portion is divided into a central region and both lateral regions, and at least one circumferential narrow groove extending zigzag along the tire circumferential direction in the central region, and between the circumferential thick groove and the circumferential narrow groove And / or a plurality of transverse grooves extending between two adjacent circumferential narrow grooves, and a land portion located in the central region is formed into an n-gonal shape (where n ≧ 6) in plan view. The block is formed into at least two rows of central block land portions, each of which is located in two adjacent central block land portions of the plurality of central block land portions. The block land portions are in a positional relationship shifted from each other in the tire circumferential direction. The block land portion located in the central block land portion row has a length in the tire width direction cross section that increases from both ends in the tire circumferential direction of the block land portion to the central portion of the block land portion, and the central block land portion row Then, the distance between the block land portions adjacent in the tire width direction is shorter than the distance between the block land portions adjacent in the tire circumferential direction, and the block land portion located in the central block land portion row adjacent to the circumferential groove is, The side wall angle on the adjacent circumferential groove is the intersection formed with the tread surface of the block land adjacent to the circumferential groove, and is small at both ends of the block land in the tire circumferential direction, and the tire circumference at the center portion. greater than opposite end portions, one of said circumferential thick groove, the block land portions located adjacent each other across a single circumferential thick groove will become disposed the tire circumferential direction position matches each other, the rest of the circumferential direction Across a large groove The block land portions positioned in contact with, a layout of the tire circumferential position shifted by a predetermined pitch from each other, wherein one circumferential thick groove, the groove opening shape, a plurality of trapezoidal shape along the tire circumferential direction The opening has a bellows shape in which the upper base and the lower base are alternately turned over and connected, and the center position of the groove bottom center of the one circumferential circumferential groove extends linearly in the tire circumferential direction. It is characterized by. If it does in this way, while being able to enlarge the freedom degree of design, it can balance both the advantage at the time of making it match with the advantage at the time of shifting the tire peripheral direction position of an adjacent block land part. .

  And as for the pneumatic tire of this invention, it is preferable that the opening groove width of the said circumferential direction large groove is 10 mm or more. This is because if the opening groove width is 10 mm or more, the intersection angle between the side wall and the tread surface at the center of the block land portion can be increased. In the present invention, “the opening groove width is 10 mm or more” means that the groove width is 10 mm or more at the narrowest opening groove width in the tire width direction.

  In the pneumatic tire of the present invention, it is preferable that the block land portion has a narrow groove having a groove width of 4 mm or less extending between the central portions of the block land portion. In this way, if a narrow groove extending between the central part of the block land part is provided, the grip force can be improved as a whole while ensuring the rigidity of the block land part, and the torque from the engine is efficiently driven. This is because it can be converted into force.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire provided with the block land part which can prevent generation | occurrence | production of uneven wear more effectively can be provided.

It is explanatory drawing which shows the displacement difference between the belt part and tread part which arise when a driving force is loaded. It is a perspective view of the block land part which can prevent partial wear and sliding wear. It is a partial development view of a tread portion of an example of a pneumatic tire according to the present invention. (A) is a perspective view of an example of a block land portion according to the present invention, and (b) is a side view of the block land portion shown in FIG. 4 (a) as seen from the tire circumferential direction. It is sectional drawing which shows an example of the shape of the circumferential direction large groove of a pneumatic tire according to this invention, and a groove bottom position along the II line, the II-II line, and the III-III line of FIG. (A)-(c) is explanatory drawing which shows the example of the block land part shape of the pneumatic tire according to this invention. (A)-(c) is explanatory drawing which shows the example of the narrow groove shape of the pneumatic tire according to this invention. (A) is a figure which shows another example of arrangement | positioning of the block land part according to this invention, (b) is the IV-IV line of FIG. It is sectional drawing shown along a V line and a VI-VI line.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the tire according to the present invention, as shown in FIG. 3, a pair of circumferential thick grooves 2 in which the opening edge of each groove wall extends in a zigzag shape along the tire circumferential direction is sandwiched between the tire equator E and the tread portion 1. The tread portion 1 is divided into a central area 5 and two side areas 6.

  Here, the central region 5 includes two circumferential narrow grooves 7 extending in a zigzag shape along the tire circumferential direction, and two adjacent circumferential grooves between the circumferential thick grooves 2 and the circumferential narrow grooves 7. A plurality of transverse grooves 8 extending between the directional narrow grooves 7 are disposed. The land portion located in the central region 5 is a hexagonal shape having a vertex projecting in the tire width direction in plan view due to the circumferential thick groove 2, the circumferential narrow groove 7, and the lateral groove 8. The block land portions 4 are divided into five rows of central block land portion rows 9. And the block land parts 4 located in the adjacent two central block land part row | line | columns 9 are in the positional relationship which mutually shifted | deviated to the tire circumferential direction. That is, the block land portions 4 of the adjacent two central block land portion rows 9 are located at half the pitch in the tire circumferential direction (half the length of the block land portion 4 in the tire circumferential direction). ) It's off.

  Further, in each lateral region 6, two adjacent circumferential narrow grooves 7 extending in a zigzag shape along the tire circumferential direction, and the two adjacent circumferential narrow grooves 2 and the circumferential narrow grooves 7. A plurality of transverse grooves 8 extending between the circumferential narrow grooves 7 and between the circumferential narrow grooves 7 and the tread ends are disposed. And the land part located in the side area 6 is a hexagon which has the vertex which planar view protrudes in a tire width direction by the circumferential direction thick groove 2, the circumferential direction fine groove 7, and the horizontal groove 8. A block land portion 10 composed of two block land portions 4 and a plurality of block land portions 12 located on the tread end side of the block land portion row 10 and having a pentagonal plan view. It is divided into rows 11.

  And the block land part 4 of the center area 5 and the block land part 4 of the side area 6 which adjoin and are located on both sides of the circumferential direction thick groove 2 are mutually shifted by a predetermined pitch in the tire circumferential direction. That is, the block land portions 4 that are adjacent to each other across the circumferential thick groove 2 are shifted by a half pitch in the tire circumferential direction (half the length of the block land portion 4 in the tire circumferential direction). ing. In this way, since the timing of stepping and kicking out the block land portion can be varied in the tire width direction, the generation of noise can be suppressed.

  Here, the circumferential thick groove 2 preferably has a groove width of 10 mm or more, and has a zigzag shape with a constant groove width along the tire circumferential direction. The circumferential narrow groove 7 preferably has a groove width of 1.0 to 5.0 mm, and the lateral groove 8 preferably has a groove width of 3.0 to 10.0 mm.

  Further, in the central region 5 of the tread portion 1, the block land portion 4 located in the central block land portion row 9 adjacent to the circumferential thick groove 2 is located on the side of the circumferential thick groove 2 adjacent to the block land portion 4. The angle of the side wall located is an intersection angle formed with the tread surface of the block land portion 4 adjacent to the circumferential thick groove 2, and is small at both ends in the tire circumferential direction of the block land portion 4, and both ends in the tire circumferential direction at the center portion Greater than. Further, in the side region 6, the block land portion 4 located in the block land portion row 10 adjacent to the circumferential thick groove 2 is a side wall located on the circumferential thick groove 2 side adjacent to the block land portion 4. The angle is an intersection angle formed with the tread surface of the block land portion 4 adjacent to the circumferential thick groove 2, and is smaller at both ends in the tire circumferential direction of the block land portion 4, and larger than both ends in the tire circumferential direction at the center portion. The block land portion 4 other than the block land portion adjacent to the circumferential thick groove 2 has a hexagonal column shape.

  Specifically, the block land portion 4 adjacent to the circumferential thick groove 2 can have a shape shown in FIG. 4, for example. In the block land portion 4, as shown in FIG. 4A, the shape of the block land portion tread 41 in contact with the road surface when traveling is a hexagon in plan view. And the angle of the side wall 42 located in the circumferential direction large groove 2 side is an intersection angle made with the tread 41 as shown in FIG. 4 (b) when the block land portion 4 is seen from the tire circumferential direction, and the block land portion 4 is smaller (angle α) at both ends in the tire circumferential direction and larger than angle α (angle β) at the center.

  3 has a groove bottom center line that connects the center positions of the groove bottoms in a zigzag shape in the tire circumferential direction (see the one-dot chain line in FIG. 3). Specifically, the cross-sectional shape of the circumferential thick groove 2 along the II, II-II, and III-III lines in FIG. 3 is as shown in FIG. Therefore, the circumferential thick groove 2 is less likely to cause stone biting.

  Further, the block land portion 4 of the tread portion 1 may be provided with a narrow groove 43 having a groove width of 4 mm or less, preferably 1 mm or less, or a shallow (depth 1 to 5 mm) hot water groove 44 extending between the central portions. good. Thus, by providing the narrow groove 43 and providing the kicking end again, the grip force of the block land portion 4 can be improved as a whole, and the torque from the engine can be efficiently converted into driving force. Is possible. In addition, the planar view shape of the block land part 4 can also be made into the shape as shown in FIG. Specifically, in addition to a general hexagon (see FIG. 6A), the hexagon is inclined (see FIG. 6B), or the octagonal edge is dropped into an octagon (see FIG. 6). (See (c)). Further, the narrow groove 43 may be bent or refracted in the block land portion 4 and may extend in a shape as shown in FIGS. 7A to 7C, for example.

  According to the pneumatic tire having the tread portion 1 configured as described above, when the block land portion 4 is grounded obliquely with respect to the road surface, compressive stress is concentrated in the central region of the block land portion 4 and the block land Force that the side wall of the block land portion 4 on the kicking end side swells in the normal direction even if the rubber in the central region of the portion 4 is deformed from the kicking end toward the stepping end. (See FIG. 2). Therefore, excessive deformation of the block land portion 4 can be suppressed, and uneven wear and sliding wear of the block land portion can be prevented. Further, since the circumferential narrow groove 7 is a narrow groove, the side walls that bulge when the block land portion 4 contacts the road surface are in contact with each other between the block land portions 4 adjacent in the tire width direction. We will support each other. Therefore, excessive deformation and destruction of the block land portion 4 can be prevented. Furthermore, the angle formed by the angle of the side wall 42 of the block land portion 4 located in the central block land portion row 9 adjacent to the circumferential thick groove 2 and the tread 41 of the block land portion 4 adjacent to the circumferential thick groove 2 is formed. Thus, it is smaller at both ends in the tire circumferential direction of the block land portion 4 and larger at both ends in the tire circumferential direction at the center portion, so that the area of the side wall on the kicking end side of the block land portion 4 adjacent to the circumferential thick groove 2 And the force that the side wall tends to bulge in the normal direction increases. Therefore, the occurrence of uneven wear can be more effectively prevented.

  Further, as shown in FIG. 8, the block land portions 4 that are partitioned and formed in the tread portion 1 of the pneumatic tire of the present invention have the tire circumferential direction positions of the adjacent block land portions 4 across the circumferential thick grooves 2. You may arrange | position so that it may correspond. In this case, the groove opening shape of the circumferential thick groove 2 is a bellows shape in which a plurality of trapezoidal openings are alternately turned over and connected along the tire circumferential direction. Further, the groove bottom center line of the circumferential thick groove 2 extends linearly in the tire circumferential direction as shown by a one-dot chain line in FIG. The cross-sectional shape of the circumferential thick groove 2 is as shown in FIG. And according to arrangement | positioning of the block land part 4 as mentioned above, drainage can be improved. In addition, since the timing of stepping and kicking out the block land portion is the same in the tire width direction, stability during straight traveling can be increased.

  Further, the pneumatic tire of the present invention may further include a plurality of circumferential thick grooves 2 in the central region 5, and the tire circumferential position of the block land portion 4 adjacent to the circumferential thick grooves 2 is The block land portions located adjacent to each other with the circumferential circumferential grooves positioned adjacent to each other are located adjacent to each other with the block land portions located adjacent to each other across at least one circumferential thick groove. The tire circumferential direction positions may be shifted from each other by a predetermined pitch. If it does in this way, while being able to enlarge the freedom degree of design, it can balance both the advantage at the time of making it match with the advantage at the time of shifting the tire peripheral direction position of an adjacent block land part. .

Example 1
A tire having block land portions arranged as shown in FIG. 8 with the specifications shown in Table 1 was made as a heavy load tire having a tire size of 495 / 45R22.5, and performance evaluation was performed by the following method. In addition, the load per tire at the time of running test is 5800 kg, the internal pressure is 900 kPa, the groove depth in the tire circumferential direction of the tread portion is 15 mm, the groove depth in the tire width direction is 12 mm, and the shoulder block The width was 60 mm.
( Reference Examples 2 to 4)
The arrangement of the block land portions was as shown in FIG. 3, and a heavy-duty tire having a tire size of 495 / 45R22.5 was prototyped according to the specifications shown in Table 1, and performance evaluation was performed by the following method. In addition, the load per tire at the time of running test is 5800 kg, the internal pressure is 900 kPa, the groove depth in the tire circumferential direction of the tread portion is 15 mm, the groove depth in the tire width direction is 12 mm, and the shoulder block The width was 60 mm.
(Conventional example 1, Comparative examples 1 to 4)
Except for changing to the specifications shown in Table 1, a heavy duty tire having a tire size of 495 / 45R22.5 was made in the same manner as in Reference Example 2, and performance evaluation was performed by the following method. In addition, the load per tire at the time of running test is 5800 kg, the internal pressure is 900 kPa, the groove depth in the tire circumferential direction of the tread portion is 15 mm, the groove depth in the tire width direction is 12 mm, and the shoulder block The width was 60 mm.

<DRY stability (steering stability on dry road)>
On a dry road surface, a straight running was performed at a speed of 80 km / h, and then a turning run was performed to reduce the turning radius from a radius of 70 m to a slalom having a radius of 20 m. The test driver evaluated the steering stability at that time. Then, the conventional example 1 was set to 100, and the DRY operability was evaluated as an index (the higher the value, the better the DRY operability). The results are shown in Table 2.
<WET operability (operation stability on WET road surface)>
On the WET road surface, new and 50% worn tires are installed, and after running straight at 80km / h, the turning radius is reduced from 70m to 40m and the turning stability is tested. The driver gave a score and evaluated. And the prior art example 1 was set to 100, and the WET operability was evaluated as an index (the higher the value, the better the WET operability). The results are shown in Table 2.
<Noise level>
The test driver scored and evaluated the noise feeling when traveling straight at a speed of 80 km / h on a dry road surface. Then, the noise level was indexed with the conventional example 1 as 100 (the higher the numerical value, the lower the noise level). The results are shown in Table 2.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Circumferential thick groove 4 Block land part 5 Central region 6 Side region 7 Circumferential narrow groove 8 Lateral groove 9 Central block land part row 10 Block land portion row 11 Block land portion row 41 Tread surface 42 Side wall 43 Narrow groove 44 Yuzo

Claims (4)

In the tread portion, a pair of circumferentially thick grooves, in which the opening edge of each groove wall extends in a zigzag shape along the tire circumferential direction, is disposed across the tire equator, and the tread portion is formed in a central area and both lateral areas. Divided into
In the central region, between at least one circumferential narrow groove extending in a zigzag shape along the tire circumferential direction, between the circumferential thick groove and the circumferential narrow groove, and / or between two adjacent circumferential narrow grooves. A plurality of lateral grooves extending, and the land portion located in the central region is formed of a plurality of block land portions each having an n-gonal shape (where n ≧ 6) in a plan view. It is divided into block land rows,
Among the plurality of central block land portion rows, the block land portions located in the adjacent two central block land portion rows are in a positional relationship shifted from each other in the tire circumferential direction,
The block land portion located in the central block land portion row, the length of the cross section in the tire width direction increases from the tire circumferential direction both ends of the block land portion to the center portion of the block land portion,
In the central block land portion row, the distance between the block land portions adjacent in the tire width direction is shorter than the distance between the block land portions adjacent in the tire circumferential direction,
The block land portion located in the central block land portion row adjacent to the circumferential thick groove has an angle of intersection between the side wall angle of the adjacent circumferential groove portion and the tread surface of the block land portion adjacent to the circumferential groove. a manner, small in the tire circumferential ends of the block land portion, rather greater than the tire circumferential ends at the central portion,
The block land portions located adjacent to each other across the circumferential thick groove are arranged such that the tire circumferential direction positions coincide with each other.
The circumferential thick groove has a bellows shape in which a groove opening shape is formed by connecting a plurality of trapezoidal openings along the tire circumferential direction by alternately inverting the upper base and the lower base, and the circumferential thick groove A pneumatic tire characterized in that a groove bottom center position of the groove has a shape extending linearly in the tire circumferential direction . In the tread portion, a pair of circumferentially thick grooves, in which the opening edge of each groove wall extends in a zigzag shape along the tire circumferential direction, is disposed across the tire equator, and the tread portion is formed in a central area and both lateral areas. Divided into
In the central region, between at least one circumferential narrow groove extending in a zigzag shape along the tire circumferential direction, between the circumferential thick groove and the circumferential narrow groove, and / or between two adjacent circumferential narrow grooves. A plurality of lateral grooves extending, and the land portion located in the central region is formed of a plurality of block land portions each having an n-gonal shape (where n ≧ 6) in a plan view. It is divided into block land rows,
Among the plurality of central block land portion rows, the block land portions located in the adjacent two central block land portion rows are in a positional relationship shifted from each other in the tire circumferential direction,
The block land portion located in the central block land portion row, the length of the cross section in the tire width direction increases from the tire circumferential direction both ends of the block land portion to the center portion of the block land portion,
In the central block land portion row, the distance between the block land portions adjacent in the tire width direction is shorter than the distance between the block land portions adjacent in the tire circumferential direction,
The block land portion located in the central block land portion row adjacent to the circumferential thick groove has an angle of intersection between the side wall angle of the adjacent circumferential groove portion and the tread surface of the block land portion adjacent to the circumferential groove. And smaller at both ends in the tire circumferential direction of the block land portion, larger than both ends in the tire circumferential direction at the center portion,
Among the circumferential thick groove, the block land portions located adjacent each other across a single circumferential thick groove will become disposed the tire circumferential direction position matches with each other, adjacent to each other across the rest of the circumferential thick groove The block land portion is positioned so that the positions in the tire circumferential direction are shifted from each other by a predetermined pitch ,
The one circumferentially thick groove has a bellows shape in which the groove opening shape is formed by connecting a plurality of trapezoidal openings along the tire circumferential direction by alternately turning over the upper base and the lower base, and A pneumatic tire characterized in that the center position of the groove bottom of one circumferential groove has a shape extending linearly in the tire circumferential direction . The pneumatic tire according to claim 1 or 2, wherein the circumferential thick groove has an opening groove width of 10 mm or more. The pneumatic tire according to any one of claims 1 to 3 , wherein the block land portion has a narrow groove having a groove width of 4 mm or less extending between central portions of the block land portion.

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