JP2849576B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of improving performance on ice and driving performance on dry pavement.

[0002]

2. Description of the Related Art Since the use of spiked tires has been banned to prevent road damage and dust pollution, pneumatic tires called so-called studless tires have been widely used in snowy areas and the like. In recent years, such pneumatic tires have adopted a block pattern in which a large number of blocks are formed on a tread surface, in addition to the development of a tread rubber material or the like which can maintain flexibility even in a low-temperature environment, and a large number of blocks are used. The performance on snow is greatly improved by the provision of siping.

[0003] However, pneumatic tires without spikes are still inferior to spiked tires in terms of running performance on slippery icy roads. Therefore, this type of pneumatic tire has been conventionally improved in performance on ice. There have been many suggestions for doing so.

For example, Japanese Unexamined Patent Publication (Kokai) No. 59-199306 discloses that a large number of blocks are formed on a tread surface, and each block has a wavy shape substantially in the tire axial direction as shown in FIG. It is proposed to improve the on-ice performance by increasing the edge component of the sipe by forming a sipe b extending.

[0005]

However, FIG.
In the case of the siping b as shown in (A), when the block a receives the shear force F in the tire circumferential direction as shown in FIG.
In addition to damage such as chipping of the blocks, satisfactory improvement of the performance on ice cannot be obtained due to a decrease in the rigidity of the blocks and a decrease in the ground contact area, and the steering performance also decreases on dry paved roads.

The present invention has been devised in view of the above-mentioned problems, and while improving the on-ice performance by increasing the edge component of the sipe, the on-ice performance is suppressed by suppressing the opening of the sipe. The purpose of the present invention is to provide a pneumatic tire capable of improving the driving performance of a dry pavement road.

[0007]

Means for Solving the Problems In the present invention, claim 1 is provided.
The described invention provides a tread groove comprising a vertical groove extending in the tire circumferential direction and a horizontal groove extending in a direction intersecting the vertical groove on a tread surface between the tread edges E, E. Alternatively, a block surrounded by a side wall formed by the tread edge is formed, and the block has a siping formed by connecting a first opening that opens on one side wall and a second opening that opens on another side wall. A pneumatic tire including a sipe-containing block, wherein the sipe includes a first sipe piece extending into the block from the first opening, and a second sipe piece extending into the block from the second opening. Between the inner ends of the first and second siping pieces, the first and second siping pieces are bent and inclined with respect to a virtual reference straight line connecting the first opening and the second opening. Together comprising a central inclined portion splicing, the sipes, first, the length of the reference straight line parallel to parallel component of the second sipes piece W1, W2 sum of (W
1 + W2) is is larger in than the length W of the reference straight line, the first, together and before the a substantially Z-shape by having the parallel component overlaps the overlapping portion of the second sipes piece
The siping may be a first siping piece or a second siping.
The pneumatic tire is characterized in that the tongue is bent in a zigzag or wavy shape .

Further, in the invention described in claim 2, the siping is defined by each ratio (V) between the length V of the overlapping portion and the lengths W1 and W2 of the parallel components of the first and second siping pieces.
/ W1) and (V / W2) are 0.1 or more and 0.67 or less.

Further, in the invention according to claim 3, in the siping, the inclination angle θ of the central inclined portion is larger than 0 ° and equal to or less than 83 °, and the reference straight line is aligned with the tire axial direction. And extends within an angle range of ± 15 °.

Further, in the invention according to claim 4, the siping has a length 0.1 times the length W of the reference straight line from an inner end of the first siping piece to the first siping piece and the center inclined. Depth D1 of the first bent portion in the range separated to the side
B is smaller than the average depth D1A of the first siping piece excluding the first bent portion, and is 0.1 times the length W of the reference straight line from the inner end of the second siping piece. Second
Of the siping piece and the second part of the area separated by the central slope
The average depth D2B of the bent portion is smaller than the average depth D2A of the second siping piece excluding the second bent portion, and the central slope excluding the first bent portion and the second bent portion. The average depth DT of the portion is smaller than the average depths D1A and D2A of the first and second siping pieces.

[0011] In the invention of claim 5, wherein the first
The angle of intersection α1 at the acute angle where the siping piece intersects the central inclined portion at the inner end, the angle of intersection α2 at the acute angle where the second siping piece intersects the central inclined portion at the inner end, the first siping A virtual acute angle side intersection angle β at which a virtual first straight line connecting the first opening of the piece and the inner end intersects the central inclined portion.
1 and a virtual acute angle side intersection angle β2 at which the virtual second straight line connecting the second opening of the second siping piece and the inner end intersects the central inclined portion, α1−β1 ≧ 10 ° α2− It is characterized by satisfying the relationship β2 ≧ 10 °.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 illustrates a tread pattern when the pneumatic tire of the present invention is employed as a heavy-duty tire preferably used for trucks, buses, and the like. FIG. 2 shows the partial internal structure, which has a carcass 14 of a radial structure ply made of a steel cord, and a belt layer 15 made of four plies that give the carcass a tag effect and tighten. I have.

In the figure, a pneumatic tire has a tread groove TG comprising a vertical groove 3 extending in the tire circumferential direction and a horizontal groove 4 extending in a direction intersecting the vertical groove 3 on a tread surface 2 between tread edges E. To form a block 7 surrounded by the side wall 5 of the tread groove TG or the side wall 6 formed by the tread edge E. In this example, the winter tire has a configuration in which the total block surface area with respect to the total tread surface area is 60 to 67%.

In the present embodiment, each of the vertical grooves 3 is formed as a straight groove extending straight, and seven grooves are provided on the tread surface 2 as an example. Similarly, in the present embodiment, the lateral groove 4 is formed as a straight groove extending continuously between the tread edges E in the tire axial direction.
Exemplifies a vertically long rectangular shape.

The vertical grooves 3 and the horizontal grooves 4 can be formed in various shapes other than those shown in the drawings, such as those bent in a wavy shape or a zigzag shape. When the tire is filled with a normal internal pressure, the groove width measured on the tread surface is measured. However, the groove depth is preferably 5 to 20 mm, and the groove depth is, for example, 7 mm according to the previous example.
It is desirable to set it to 20 mm.

Next, the block 7 has a first opening 9 opened on one side wall 5 or 6 and another side wall 5 or 6.
Including a siping-containing block 7a in which a siping 11 extending from the second opening 10 opening at
In this example, all blocks are blocks 7 with siping.
a.

The siping 11 preferably has a groove width of 0.3 to 2.0 mm in tires for heavy loads, passenger cars, and the like. In particular, when the siping 11 is vulcanized by a mold, the thickness is desirably 0.5 to 2.0 mm in consideration of the thickness of the knife blade of the mold. When emphasis is placed, the groove width of the siping is 0.5 to 1.5 mm, more preferably 0.5 to 1.0 mm so as not to reduce the block rigidity.
It is desirable that

The siping 11 extends from the first opening 9 into the block and from the second opening 10 into the block, as is apparent from FIG. Second siping piece S2
And inner ends S1 of the first and second siping pieces S1 and S2.
i, S2i. In the present example, the first and second siping pieces S1, S2 and the central inclined portion SC are all represented by one straight line.
You. In addition, in the pneumatic tire of the present invention,
As described in claim 1, the first siping piece S1 or the first siping piece
2 siping piece S2 is bent in a zigzag or wave shape
It is a requirement to be able to get up. However, in the drawing
7 and 8, except for the first siping piece S1.
Virtual straight line V connecting the first opening 9 and its inner end S1i.
L1 (shown in FIG. 7), second opening of the second siping piece
Imaginary second straight line VL2 connecting the inner end 10 and the inner end S2i.
(Both are shown in FIG. 7).
Ping pieces S1 and S2 are displayed as straight lines.

The central inclined portion SC has first and second inclined portions.
Of the first and second siping pieces S1, S2
Imaginary reference line VL connecting the opening 9 and the second opening 10
Are arranged at an inclination angle θ with respect to. In the present embodiment, the length W of the reference straight line VL is set equal to the width of the block 7a.

Further, in the siping 11, the sum (W1 + W2) of the lengths W1 and W2 of the parallel components of the first and second siping pieces S1 and S2 parallel to the reference straight line VL is larger than the length W of the reference straight line VL. Is also large.

Thus, the siping 11 has a substantially Z-shape by having the overlapping portion 12 where the parallel components of the first and second siping pieces S1 and S2 overlap.

Such a substantially Z-shaped siping 11 is
Helping to improve on-ice performance by substantially increasing the edge component of the siping, especially the axial edge component.

Further, even if a shearing force in a direction perpendicular to the siping 11 acts on the block 7a, the siping 11 forms a substantially Z-shape as described above, so that the block small pieces 7F, 7R divided by the siping 11 are formed. Can engage with each other to suppress the opening of the siping 11 as shown in FIG. 4, so that damage such as chipping of the block can be prevented, and a decrease in block rigidity and a decrease in ground contact area can be prevented. Steering stability on dry paved roads can be improved.

Here, the present inventors, in order to confirm that the opening of the siping 11 is suppressed, FIG.
As shown in the figure, the falling angle δ of the block was measured. This inclination angle δ is provided at 14 measurement positions at equal intervals in the circumferential length of the block, and the inclination angle of each position with respect to the normal direction is measured. The magnitude of the lateral force is 60 (kgf), and one siping is provided in the middle of the circumferential length of the block.

FIG. 5 (B) shows the results, where ● represents the result of the siping of the present embodiment, and ○ represents the result of the conventional siping consisting of one straight line (shown in FIG. 10) extending in the tire axial direction. . In the case where the siping of the present embodiment is provided,
The average falling angle of the first-arrival side after the siping is 23.3
6 °, that of the rear arrival side is 21.78 °, the difference between the two is 1.
58 °. However, with conventional siping,
The average inclination angle of the first arrival side is 24.64 °, that of the last arrival side is 21.42 °, and the difference between them is extremely large at 3.22 °.

As described above, the siping 11 of the present invention comprises:
Falling angle δ at each of the first and last positions of the block
Is smaller than that of the conventional siping, and it can be confirmed that they fall almost uniformly. Therefore, the opening amount of the siping 11 is naturally smaller than the conventional one.

In this connection, the siping 11 of the present invention
Can make the ground pressure of the block uniform because the block falls down substantially uniformly as a whole. Therefore,
In a tire having a block pattern, uneven wear such as heel and toe wear caused by uneven contact pressure can be suppressed, and the anti-wear performance can be improved.

When the vehicle turns, a slip angle is given to the tire. When the slip angle is given in a direction intersecting with the central inclined portion SC, especially when the block 7a is integrated. As a result, the rigidity of the block is increased, so that the sliding of the block is suppressed and the steering stability performance can be further improved.

Next, the siping 11 has a ratio (V / W1) between the length V of the overlapping portion 12 and the lengths W1 and W2 of the parallel components of the first and second siping pieces. V /
W2) is preferably 0.1 to 0.9, more preferably 0.1 to 0.82, and still more preferably 0.1 to 0.6.
7, more preferably 0.18 to 0.67.

The ratios (V / W1) and (V / W2) are
In the case of 0.1 or more, the effect of preventing the opening of the siping is enhanced by making the siping 11 substantially Z-shaped,
If it is less than 0.1, the effect of preventing the opening of the siping tends to decrease, and each of the first and second siping pieces S
1, S2 tends to be close to the reference straight line VL, and a crack is easily generated at the bottom of the siping.

Conversely, each of the ratios (V / W1), (V / W
When 2) exceeds 0.9, the overlapping portion becomes large and the opening of the siping can be suppressed, but the first siping piece S1 is on the acute angle side where it intersects with the central inclined portion SC at the inner end S1i. The intersection angle α1 and the intersection angle α2 on the acute angle side where the second siping piece S2 intersects with the central inclined portion SC at the inner end S2i tend to be small, and cracks are easily generated at the intersection of the siping bottom and the like. .

From such a viewpoint, the intersection angle α
1, about α2, preferably 16 ° or more, more preferably 24 ° or more, still more preferably 36 ° to 70 °,
It is more preferable that the angle is 36 ° to 56 ° to prevent the occurrence of cracks at the intersection.

In this embodiment, the ratio (V / W)
1) and (V / W2) are equalized to exemplify a case in which the central inclined portion SC is provided at an intermediate position of the siping 11. This case is preferable in that the effect of preventing the opening of the siping is higher and the appearance of the siping as a design is improved.

The reference straight line VL of the siping is
The extension direction of the siping 11 is specified by connecting the first opening 9 and the second opening 10 of the siping. The inclination angle θ of the central inclined portion SC of the siping 11 with respect to the reference straight line VL is preferably 0 °. And 83 ° or less, more preferably 30 ° or more and 83 ° or less, still more preferably 30 ° or more and 76 ° or less, and more preferably 3 ° or more and 76 ° or less.
It is desirable that the angle is not less than 0 ° and not more than 63 °.

In this embodiment, the reference straight line VL of the siping 11 extends in the tire axial direction in order to further enhance the performance on ice by the siping 11. That is, in such a case, when the vehicle is suddenly braked, a large shearing force acts in the tire circumferential direction to push the siping 11 open, so that the effect of the present invention becomes more remarkable.

Note that such an effect is similarly exerted even when the reference straight line VL of the siping extends substantially in the tire axial direction, that is, when the reference straight line VL extends within an angle range of ± 15 ° with respect to the tire axial direction. sell.

Further, the reference straight line VL may have an angle other than ± 15 ° with respect to the tire axial direction. This case is preferable in that the opening of the siping can be prevented when the vehicle turns.

As shown in FIG. 6, the siping 11 having a substantially Z shape has a length 0.1 times the length W of the reference straight line VL from the inner end S1i of the first siping piece S1. The height t is determined by the first siping piece S1 and the central inclined portion SC.
To the first bent portion 12 in the range separated to the side, and to the second bent portion 13 in the range separated from the inner end of the second siping piece S2 to the side of the second siping piece S2 and the central inclined portion SC. In some cases, cracks are likely to occur at the bottom portion because stress tends to concentrate.

From this viewpoint, in the present embodiment, the average depth D1B of the first bent portion 12 in the siping 11
Is smaller than the average depth D1A of the first siping piece S1 excluding the first bent portion 12.

Similarly, the average depth D of the second bent portion 13
2B is smaller than the average depth D2A of the second siping piece S2 excluding the second bent portion 13.

As described above, the first and second bent portions 12 and 13
When the average depths D1B and D2B are relatively shallow, the bottom portion of each of the bent portions can be effectively reinforced, which is more preferable in that damage such as cracks can be prevented.

The ratio of the average depth (D1B / D1)
A) and (D2B / D2A) are set to about 0.6 to 0.9, preferably about 0.6 to 0.8, and it is preferable that both are equal.

Also, during turning of the vehicle, the block that is in contact with the ground receives a torsional force. In this case, a large stress is concentrated on the central inclined portion SC of the siping 11, and a crack may easily occur at the bottom.

From this point of view, as shown in FIG. 6, in this embodiment, the average depth DT of the central inclined portion SC excluding the first and second bent portions 12 and 13 is equal to the first depth DT. Average depth D of siping piece S1 and second siping piece S2
A preferred embodiment is shown in which reinforcement is made smaller than 1A and D2A to prevent cracking at the bottom of the central inclined portion SC. In this case, (DT / D1A) or (DT
/ D2A) is, for example, 0.6 to 0.9, preferably 0.1 to 0.9.
It may be about 6 to 0.8.

The first and second siping pieces S1,
The average depth D1A, D2A of S2 is 4 times the groove depth of the vertical groove 3.
The content is desirably 0 to 100%, more preferably 40 to 70%.

FIGS. 7A and 7B show the first siping.
The piece S1 and the second siping piece S2 meet the requirements of claim 1.
FIG. The form of this implementation
In the state, the first and second siping pieces S1 and S2 are both
It is bent in a zigzag shape. Therefore, d of siping 11
And the on-ice performance can be improved.

In this case, an imaginary first straight line VL1 connecting the crossing angles α1, α2 of the siping 11 and the first opening 9 of the first siping piece S1 to the inner end S1i is formed with the central inclined portion SC. A virtual acute angle side intersection angle β1 that intersects, and a virtual acute angle side intersection angle β2 where the virtual second straight line VL2 that connects the second opening of the second siping piece and the inner end intersects the central inclined portion. , Α1−β1 ≧ 10 °, α2−β2 ≧ 10 °.

In this case, the first and second siping pieces S
1, which is preferable in that the intersection angles α1, α2 between the respective inner ends S1i, S2i of the S2 and the central inclined portion SC are prevented from being sharply sharpened, so that cracks that are likely to occur at the bottom of the siping can be effectively prevented. Becomes

FIGS. 8A to 8E show still another embodiment. In this embodiment, the first and second siping pieces S1, S2 are formed by a combination of straight lines and smooth curves or arcs. Also, FIGS. (B), (C),
(D) and (E) show the positions of the first and second openings 9 and 10 shifted in the length direction of the block.

As described in detail above, only one of the first and second siping pieces S1 and S2 may be zigzag, or one or both of them may be wavy. It can be changed as appropriate, such as using a combination of zigzags. In the above example, the number of sipings is preferably one per block as a preferable one, but is not limited to this.

Further, in the pattern shown in FIG. 1, the present invention can be modified in various modes, such as those in which the sipings arranged on the left and right sides of the tread surface with respect to the tire equator C are axisymmetric.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Tire of the present invention having a tire size of 11R22.5, having the structure shown in FIGS. 1 and 2, and having variously different siping shapes (shown in FIGS. 7 and 9) (Example) 1-10) and various tests using actual vehicles were conducted. Tires whose sipings (shown in FIGS. 10 and 11) do not satisfy the requirements of the present invention (Comparative Example 1,
For 2), a prototype was also produced and the performance was compared. Details such as the tire structure are as follows.

Belt layer Belt layer Steel cord (3 + 6) 4 plies, angle of steel cord to tire equator C (from inside radial direction of tire) 50 ° R, 18 ° R, 18 ° L, 18
° L Carcass One ply of steel cord (3 + 7), angle of steel cord with respect to tire equator C: 90 ° Tread width (ground contact width) TW = 230 mm Block size Tire circumferential length 30 mm, tire axial width 20 mm

In the test, a test tire was measured at 7.50 × 22.
5 rims (internal pressure 8.0 kgf / cm ² ), 2/2
-D was mounted on all wheels of a vehicle (load capacity of 10 tons) and performed as follows.

A) Braking performance on ice On a slippery icy road, the braking distance was examined by applying lock sudden braking from a speed of 30 km / h, and the comparative example 1 was evaluated as 1
It is indicated by an index of 00. The larger the value, the shorter the braking distance and the better the braking performance on ice.

(B) Cornering performance on ice On a slippery icy road, the test course was circled, and the evaluation was made according to the index of Comparative Example 1 as 100 by the feeling of the test driver. The larger the value, the better the cornering performance on ice.

(C) Steering stability of the actual vehicle The vehicle was run on a dry pavement and evaluated according to the feeling of the test driver. The higher the value, the better the steering stability on dry roads.

D) Actual vehicle durability performance After completing a running distance of 10,000 km (breakdown: about 5000 km on a dry pavement, 2500 km on a wet pavement, 2500 km on a dirt road), check the tread surface for damage, and The damage condition of the tire with the most damage and the magnitude of the damage are described. Table 1 shows the test results.

[0059]

[Table 1]

As a result of the test, it was confirmed that the performance of the example was improved on ice and the steering performance on the dry pavement was improved as compared with that of the comparative example.

[0061]

According to the pneumatic tire of the present invention, the substantially Z-shaped siping can improve the performance on ice by substantially increasing the edge component of the siping.

Even if a shear force acts on the block,
Since the opening of the siping can be suppressed by making the siping substantially Z-shaped, it is possible to prevent damage such as chipping of the block, and to prevent a decrease in block rigidity and a decrease in the ground contact area, thereby improving performance on ice. Steering stability on dry paved roads can be improved.

Further, the provision of the substantially Z-shaped siping allows the block to fall down substantially uniformly as a whole and the ground pressure of the block to be uniform, so that uneven wear such as heel and toe wear can be achieved. Can also be suppressed.

[Brief description of the drawings]

FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention.

FIG. 2 is a partial sectional view showing the internal structure of the tire.

FIG. 3 is an enlarged plan view showing details of a block.

FIG. 4 is a schematic diagram showing the behavior of the block when the ground is touched.

FIG. 5A is a side view illustrating a measurement position,
(B) is a graph showing a test result of the present invention.

FIG. 6 is a perspective view of a block for explaining a depth of siping.

7 (A), is a plan view showing an implementation form of (B) the present invention.

8 (A) to 8 (E) are plan views of blocks showing another embodiment of the present invention.

FIG. 9 is a plan view of a block showing another embodiment of the present invention.

FIG. 10 is a plan view of a block of a comparative example.

FIG. 11 is a plan view of a block according to a comparative example.

FIG. 12A is a plan view illustrating a conventional siping, and FIG. 12B is a conceptual diagram illustrating its behavior.

[Explanation of symbols]

2 Tread surface 3 Vertical groove 4 Horizontal groove 5, 6 Side wall 7 Block 9 First opening 10 Second opening 11 Siping 12 Overlapping part S1 First siping piece S2 Second siping piece SC Central inclined part S1i First siping piece S2i Inner end of second siping piece VL Reference straight line W Length of reference straight line W1 Length of parallel component parallel to reference straight line of first siping piece W2 Length of parallel component parallel to reference straight line of second siping piece Length θ Inclination angle of center inclined portion with respect to reference straight line V Length of overlapping portion V D1B Average depth of first bent portion D2B Average depth of second bent portion D1A Average depth of first siping piece D2A First siping Average depth of the piece DT Average depth of the central inclined portion α1 Intersection angle of the acute angle side where the first siping piece intersects the central inclined portion at the inner end α2 The second siping piece is forward at the inner end Intersecting angle β1 on the acute angle side intersecting with the central inclined portion β1 Intersecting angle on the acute acute side intersecting the first opening of the first siping piece and the inner end with the central inclined portion β2 Second siping piece A virtual second straight line connecting the second opening and the inner end of the virtual inclined line intersects the central inclined portion at a virtual acute angle side intersection angle

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-254406 (JP, A) JP-A-7-1919 (JP, A) JP-A-4-228308 (JP, A) JP-A-5-228 104909 (JP, A) JP-A-2-246810 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60C 11/11 B60C 11/12

Claims (5)

(57) [Claims] 1. A tread groove comprising a vertical groove extending in the tire circumferential direction and a horizontal groove extending in a direction intersecting the vertical groove is provided on a tread surface between tread edges E, E, so that a groove wall of the tread groove is provided. Or, while forming a block surrounded by a side wall formed by the tread edge, the block, a first opening that is opened by one side wall,
A pneumatic tire including a sipe-containing block formed with a sipe extending in connection with a second opening that is opened on another side wall, wherein the sipe extends from the first opening into the block. A second siping piece extending into the block from the second opening; and a first opening formed by bending the first and second siping pieces between inner ends of the first and second siping pieces. And a central inclined portion inclined and connected to an imaginary reference straight line connecting the second opening and the second opening. The siping has a length of a parallel component of the first and second siping pieces parallel to the reference straight line. Sum of W1 and W2 (W1 +
W2) is greater than the length W of the reference straight line, has a substantially Z-shape by having an overlapping portion where the parallel components of the first and second siping pieces overlap each other , and The first siping piece or the second
A pneumatic tire, wherein a siping piece is bent in a zigzag or wave shape . 2. The siping has a length V
And the length W of the parallel component of the first and second siping pieces.
1 and W2, each ratio (V / W1), (V / W2) is 0.
The pneumatic tire according to claim 1, wherein the value is not less than 1 and not more than 0.67. 3. The siping is such that the inclination angle θ of the central inclined portion is greater than 0 ° and 83 ° or less, and the reference straight line has an angle of ± 15 ° with respect to the tire axial direction.
The pneumatic tire according to claim 1, wherein the pneumatic tire extends within a range . 4. The method according to claim 1, wherein the siping is performed by extending the length of the reference straight line from the inner end of the first siping piece by 0.1 to 1 times the length W of the reference straight line.
Of the siping piece and the first part of the area separated by the central inclined part side
The average depth D1B of the bent portion is smaller than the average depth D1A of the first siping piece excluding the first bent portion, and the length W of the reference straight line W from the inner end of the second siping piece. Average depth D2B of the second bent portion in a range separating the 0,1 times length to the second siping piece and the center inclined portion side
Is smaller than the average depth D2A of the second siping piece excluding the second bent portion, and the average depth DT of the central inclined portion excluding the first bent portion and the second bent portion is The pneumatic tire according to claim 1, wherein the average depth D1A, D2A of the first siping piece and the second siping piece is smaller. 5. The siping according to claim 1, wherein the first siping piece or the second siping piece is bent in a zigzag or wavy manner, and the first siping piece intersects the central inclined portion at an inner end at an acute angle side. An angle α1, an acute angle side intersection angle α2 at which the second siping piece intersects the central inclined portion at the inner end, and a virtual first straight line connecting the first opening of the first siping piece and the inner end. A virtual acute angle side intersection angle β1 intersecting with the central inclined portion, and a virtual acute angle side intersection where a virtual second straight line connecting the second opening and the inner end of the second siping piece intersects with the central inclined portion. 2. The pneumatic tire according to claim 1, wherein the angle β2 satisfies a relationship of α1−β1 ≧ 10 ° and α2−β2 ≧ 10 °.