JP2007176282A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve abrasion resistant performance without lowering on-snow travelling performance. <P>SOLUTION: First and second block rows R1, R2 in which blocks divided by lateral grooves 4 are arranged in the circumferential direction on both sides of a piece of longitudinal groove 3b extending in the circumferential direction are arranged on a tread part 2. A plurality of sipings S are formed on each of the blocks 5a, 5b of the first and second block rows. The lateral grooves 4a, 4b actually open at opposed positions through the longitudinal groove 3a. Deformation restraining parts 6 to restrain deformation in the tire circumferential direction of the blocks facing the lateral grooves are provided on the lateral grooves 4a, 4b of the first and second block rows R1, R2. The deformation restraining parts 6 are arranged on every other blocks in the circumferential direction on each of the block rows R1, R2 and arranged zigzag to straddle over the longitudinal groove 3a by dislocating their phases in the tire circumferential direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire having a plurality of block rows in a tread portion, and more particularly to a pneumatic tire capable of improving uneven wear resistance performance without deteriorating running performance on snow.

  Conventionally, in a pneumatic tire such as a studless tire suitable for traveling on an icy and snowy road, a plurality of block rows are formed in the tread portion, and each block row has a plurality of blocks extending in the tire axial direction. A book siping is formed (see Patent Documents 1 and 2 below). In this type of pneumatic tire, the thin water film on the ice road surface is removed by the edge effect or wiping effect of siping, and the grip force necessary for driving and braking is ensured.

JP2003-63211A JP-A-2005-47397

  However, when a block provided with siping travels on a road surface where a sufficient grip force is obtained, such as a dry asphalt road surface, the amount of deformation at the end of the block in the tire circumferential direction during driving or braking and the road surface The amount of slip increases. For this reason, uneven wear such as heel and toe wear where wear concentrates on the end of the block is likely to occur. In particular, in a studless tire in which a soft rubber composition is used for the tread portion, the above-described uneven wear appears more remarkably.

  The present invention has been devised in view of the above situation, and provided with a deformation suppressing portion that suppresses deformation in the tire circumferential direction of the block in the horizontal groove of the adjacent block row via the vertical groove, Based on the fact that one deformation suppression part is placed in the tire circumferential direction in each block row and its phase is shifted in the tire circumferential direction, it is arranged in a zigzag shape straddling the vertical groove, and the running performance on snow is improved. The main object is to provide a pneumatic tire that can suppress the occurrence of uneven wear without reducing it.

  The invention according to claim 1 of the present invention is the first block row in which blocks divided by lateral grooves are arranged in the tire circumferential direction on both sides of one vertical groove extending continuously in the tire circumferential direction on the tread portion. And a plurality of sipings extending in the tire axial direction are formed in each block of the first and second block rows, and the first block. The horizontal groove of the row and the horizontal groove of the second block row are opened at positions substantially opposed to each other via the vertical groove, and the horizontal groove of the first block row and the second block row includes: A deformation suppressing portion that suppresses deformation in the tire circumferential direction of the block facing the lateral groove is provided, and the deformation suppressing portions are arranged alternately in the tire circumferential direction in each block row, and the phase thereof is changed to the tire. Shift in the circumferential direction Characterized in that it is arranged in a zigzag pattern across the longitudinal groove by the.

  According to a second aspect of the present invention, the deformation suppressing portion is a tie bar in which the groove depth of the transverse groove is reduced by raising the groove bottom and / or a narrow portion in which the groove width of the transverse groove is partially reduced. The pneumatic tire according to Item 1.

  According to a third aspect of the present invention, in the lateral groove of the first block row, the deformation suppressing portion is formed of the tie bar, and in the second block row, the deformation suppressing portion is formed of a narrow portion. 2. The pneumatic tire according to 2.

  According to a fourth aspect of the present invention, the first block row is disposed at a position closest to the tire equator, and the second block row is disposed on the outer side in the tire axial direction. It is a pneumatic tire.

  According to a fifth aspect of the present invention, the lateral groove of the first block row has a greater depth on the second block row side by providing the tie bar on the tire equator side. Tire.

  According to a sixth aspect of the present invention, the tread portion includes a third block in which a plurality of blocks that are partitioned by lateral grooves and provided with a plurality of sipings are arranged in the tire circumferential direction on the outer side in the tire axial direction of the second block row. The horizontal groove of the third block row having a block row is provided at a position that does not face the horizontal groove of the second block row, and the pitch in the tire circumferential direction of the siping provided in the block of the third block row Is a pneumatic tire according to any one of claims 1 to 5, which is larger than a pitch in the tire circumferential direction of siping provided in the blocks of the second block row.

  In the present invention, the tread portion is provided with first and second block rows adjacent to each other through vertical grooves, and a plurality of sipings extending in the tire axial direction are formed in each block. By these, performance on snow and performance on ice are exhibited. Further, a deformation suppressing portion that suppresses deformation in the tire circumferential direction is provided in the lateral groove of the first and second block rows. Therefore, the wear resistance of the block is improved. Furthermore, since the deformation suppressing portions are arranged in a zigzag manner across the longitudinal grooves by placing one in the tire circumferential direction in each block row and shifting the phase in the tire circumferential direction, the performance on snow is improved. The uneven wear resistance performance is improved without causing a significant decrease.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a development view of the tread portion 2 of the pneumatic tire of the present embodiment. The tread portion 2 is provided with a plurality of vertical grooves 3 extending continuously in the tire circumferential direction and a plurality of horizontal grooves 4 extending in a direction intersecting with the vertical grooves. The pneumatic tire of this embodiment is configured as a studless tire for passenger cars.

  The vertical groove 3 includes one central vertical groove 3a extending on the tire equator C, a pair of external vertical grooves 3c, 3c arranged on both sides thereof and extending most on the ground contact end E side. It includes a pair of intermediate vertical grooves 3b and 3b extending between the groove 3c and the central vertical groove 3a. In the present embodiment, the longitudinal grooves 3b and 3c are provided at substantially symmetrical positions with respect to the tire equator C.

  In the present embodiment, the central longitudinal groove 3a extends linearly in the tire circumferential direction. On the other hand, the intermediate and outer longitudinal grooves 3b and 3c are formed in a zigzag shape with a small pitch and amplitude at the groove edges, but extend substantially along the tire circumferential direction. Such a groove is preferable in terms of increasing the length of the edge and thus improving the gripping force on ice. However, the shape of the longitudinal groove 3 is not limited to such a form, and can include various shapes such as a wave shape and a clear zigzag shape.

  The width and depth of each longitudinal groove 3 in the tire axial direction are not particularly limited, but the groove width in the tire axial direction of the longitudinal groove 3 is preferably 4 mm or more in order to exhibit sufficient running performance on snowy roads. More preferably, it is 5 mm or more, and the upper limit is preferably 8 mm or less, more preferably 7 mm or less. The depth of the longitudinal groove 3 is preferably 8 mm or more, more preferably 9 mm or more, and preferably 12 mm or less, more preferably 11 mm or less.

  The transverse groove 4 includes a central transverse groove 4a extending across the central longitudinal groove 3a and the intermediate transverse groove 3b, and an intermediate transverse groove 4b extending across the intermediate longitudinal groove 3b and the outer longitudinal groove 3c. And an outer lateral groove 4c extending between the outer longitudinal groove 3c and the ground contact E.

  As a result, the first block row R1 in which the center block 5a is arranged in the tire circumferential direction is formed between the central vertical groove 3a and the intermediate vertical groove 3b, and the intermediate vertical groove 3b and the outer vertical groove 3c. A second block row R2 in which the middle blocks 5b are arranged in the tire circumferential direction is interposed therebetween, and a third block row R3 in which the shoulder blocks 5c are arranged in the tire circumferential direction between the outer vertical groove 3c and the ground contact E. Is formed.

  Each of the blocks 5a to 5c is provided with a plurality of sipings S extending in the tire axial direction and spaced substantially in parallel. Each siping S is formed as a slit-like cut having a narrow width so that the wall surfaces come into contact with each other during traveling. Although not particularly limited, the thickness of the siping S is preferably about 0.3 to 1.0 mm, for example. The depth of the siping S is not particularly limited, but is preferably 50 to 100%, more preferably about 60 to 85% of the maximum depth of the lateral groove 4.

  In addition, “siping extending in the tire axial direction” means that a straight line connecting both ends of the siping S is inclined at 45 degrees or less with respect to the tire axial direction, and more preferably at a small angle of 0 to 35 degrees. It is desirable to be tilted. Furthermore, the siping S can be formed by combining one or more of various shapes such as a straight shape, a wavy shape and / or a zigzag shape. As the particularly preferred siping S, a full open or semi-open type in which the central portion is zigzag and the straight portions are connected to both ends, particularly, both ends open to the longitudinal groove 3 as shown in FIG. 1 is desirable. . Such a siping S can exhibit an excellent grip performance on ice by functioning an edge in various directions.

  Although not particularly limited, the groove width of each lateral groove 4 is preferably 3 mm or more, more preferably 5 mm or more, and preferably 9 mm in order to exhibit a high snow column shearing ability in a snowy road. Hereinafter, it is desirable to include a portion of 7 mm or less. Moreover, the groove depth of the horizontal groove 4 is not particularly limited, but preferably 90 to 100% of the groove depth of the vertical groove 3 is included.

  In the present embodiment, the central lateral groove 4a is inclined at a small angle, for example, about 5 to 30 degrees with respect to the tire axial direction. Thereby, the center block 5a is divided into substantially parallelogram shapes. Further, the central lateral grooves 4a are arranged at a substantially constant pitch in the tire circumferential direction. Since the pitch is “almost constant”, the central lateral groove 4a can have a varying pitch based on a variable pitch technique or the like.

  In the present embodiment, the intermediate lateral groove 4b is formed in a substantially V shape including a portion that protrudes to one side in the tire circumferential direction at the intermediate portion in the length direction. Such an intermediate lateral groove 4b can be expected to improve the biting property to the road surface on a snowy road. In addition, on an icy road, a high grip force can be obtained by increasing the edge length and causing the edge to function in various directions. Moreover, it is desirable that the inclination of the intermediate lateral groove 4b with respect to the tire axial direction is smaller than that of the central longitudinal groove 4a. Thereby, the rigidity of the both ends of the tire circumferential direction of the middle block 5b improves, and the heel and toe wear is suppressed.

  Further, the middle block 5 divided by the intermediate lateral groove 4b is provided with a small groove 9 extending substantially in the middle in the width direction in the tire circumferential direction. The small groove 9 is formed with, for example, a groove width of 20 to 50% of the vertical groove 3 and a groove depth of 20 to 50% of the groove depth of the vertical groove 3. The small groove 9 is preferably non-linear. The small groove 9 of the present embodiment includes the bent portion and extends in the tire circumferential direction, thereby increasing the groove edge and further improving the performance on ice.

  The intermediate horizontal groove 4b provided in the second block row R2 is opened at a position substantially opposed to the central horizontal groove 4a of the first block row R1 through the intermediate vertical groove 3b. Here, “substantially opposite” means that, as shown in FIG. 2 (A), a plane VP parallel to the plane including the tire equator C is located on the side of the intermediate longitudinal groove 3b of each lateral groove 4a, 4b. The projection openings 4ao and 4bi (which are shown in FIG. 2B) that project the openings have an overlapping portion X that overlaps at least partly.

  In this way, by opening the central lateral groove 4a and the intermediate lateral groove 4b to face each other through the intermediate longitudinal groove 3b, a groove crossing portion G having a substantially cross shape as shown in FIG. Can be formed. The groove crossing portion G can form a large cross-shaped snow column with high rigidity on the ground contact surface when traveling on a snowy road, and can shear it, thereby exerting a large driving or braking force. Therefore, the pneumatic tire 1 of the present embodiment can significantly improve the snow road running performance.

  On the other hand, at the groove crossing portion G, the corner portions 5ae and 5be of the center block 5a and the middle block 5b approach each other, and heel and toe wear is likely to occur at the portions. The reason is that when slippage occurs at the corner portion 5ae of one block 5a, it is presumed that the slip is transmitted to the corner portion 5be of the other block 5b via the vertical groove 3b.

  Therefore, in the present embodiment, the central lateral groove 4a and the intermediate lateral groove 4b are provided with a deformation suppressing portion 6 that can suppress deformation in the tire circumferential direction of the block facing the lateral groove, for example, collapse deformation.

  In one embodiment, the deformation suppressing portion 6 is formed by raising the groove bottom of the lateral groove 4 as shown in, for example, FIG. 3A and FIG. In this example, a tie bar 7 in which the groove depth d2 of the lateral groove 4 is partially reduced to d1 is included. The tie bar 7 of this embodiment is shown by partially reducing the groove depth d2 of the lateral groove 4. Such a tie bar 7 can suppress deformation in the tire circumferential direction of the blocks 5a and 5a arranged on both sides thereof, thereby suppressing slippage at both ends of the block 5a in the tire circumferential direction, and thus uneven wear on the blocks 5a and 5a. Can be suppressed.

  Although there is no particular limitation, if the depth d1 of the portion of the lateral groove 4 where the tie bar 7 is provided is too small, there is a risk that the snow drainage performance on the snow will deteriorate, and conversely if it is too large, the above-mentioned block There is a possibility that the deformation suppressing effect of the material is reduced. From this point of view, the depth d1 of the lateral groove 4 is preferably 10% or more, more preferably 30% or more of the maximum depth d2 of the lateral groove 4, and the upper limit is preferably 80% or less. More preferably, 50% or less is desirable. However, when the tie bar 7 is provided over the entire length range of the horizontal groove 4, the maximum depth d2 is the same as the maximum depth of the horizontal groove (described later) that is not provided with the tie bar 7. Is adopted.

  In the present embodiment, the tie bar 7 includes a base portion 7a extending in the transverse groove at a constant height, and a sub-portion 7b that is connected to the base portion 7a and gradually decreases in height. In this embodiment, the tie bar 7 is composed of one base portion 7a and one sub-portion 7b. However, the configuration of the tie bar 7 is not limited to the mode shown in the figure, and includes various modes such as a mode having sub-parts 7b on both sides of the base 7a, and a type whose height repeatedly increases and decreases.

  The length TL along the horizontal groove 4 of the tie bar 7 is also not particularly limited. However, if it is too small, the above-described deformation suppressing effect of the block 5 tends to be lowered, and conversely if too large, drainage performance, performance on snow, etc. may be degraded. . From this point of view, the length TL of the tie bar 7 along the lateral groove 4 is preferably 20% or more, more preferably 40% or more of the total length GL of the lateral groove 4, and the upper limit is preferably 80%. Below, 60% or less is more desirable.

  FIG. 4 shows a cross-sectional view taken along the line BB in FIG. As shown in FIG. 4 (A), the tie bar 7 can be formed integrally with the groove walls 4w, 4w of the lateral groove 4. In this case, deformation of the block 5a in the tire circumferential direction is further effectively suppressed. Further, as shown in FIG. 4B, the tie bar 7 may be separated from the groove walls 4w and 4w by narrow slits 7e and 7e. In this embodiment, since the reduction in the groove volume is minimized, it is preferable in that the reduction in drainage and the like are suppressed.

  Moreover, as shown in FIG. 5, the deformation | transformation suppression part 6 can contain the narrow part 8 which reduced the groove width W1 of the horizontal groove 4 partially to W2, as FIG. 5 shows. When the shearing force in the tire circumferential direction acts on the block 5 b, the narrow narrow portion 8 easily contacts the groove walls and integrates the adjacent blocks 5 b and 5 b via the narrow portion 8. As a result, the rigidity of the block can be increased and deformation in the tire circumferential direction can be suppressed. Therefore, the narrow portion 8 can also suppress slippage at both ends of the block 5a in the tire circumferential direction and improve its uneven wear resistance.

  Although not particularly limited, if the groove width W2 of the narrow portion 8 is too large, the above-described block deformation suppressing effect may be reduced. From such a viewpoint, the groove width W2 of the narrow portion 8 is preferably 1.8 mm or less, more preferably 1.0 mm or less.

  The length SL of the narrow portion 8 is not particularly limited, but if it is too small, the above-described block deformation suppressing effect may be reduced, and conversely if it is too large, the snow drainage tends to be remarkably reduced. From such a viewpoint, the length SL of the narrow portion 8 is preferably 20% or more, more preferably 30% or more of the total length GL of the lateral groove 4, and the upper limit is preferably 50% or less. Preferably it is 40% or less.

  Here, the length TL of the tie bar 7, the length of the narrow portion 8, and the total length of the lateral groove 4 are all path lengths along the groove center line GC (shown in FIG. 5) of the lateral groove 4. .

  Although not shown, the deformation suppressing unit 6 naturally includes a mode in which the groove bottom of the narrow portion 8 is raised.

  As shown in FIG. 1, in the pneumatic tire 1 of the present embodiment, the deformation suppressing portions 6 are arranged alternately in the tire circumferential direction in the first and second block rows R1 and R2, respectively. By shifting the phase in the tire circumferential direction, the deformation suppressing portion 6 is disposed in a zigzag shape while straddling the intermediate vertical groove 3b. In other words, when the deformation suppressing portions 6 provided on both sides of the intermediate vertical groove 3b are alternately connected, a zigzag curve is drawn.

  While the deformation suppressing unit 6 suppresses uneven wear of the block, the groove volume of the lateral groove 4 is partially reduced, so that there is a tendency to reduce snow drainage. In particular, when the deformation suppressing portions 6 are provided in all the horizontal grooves 4a and 4b of the block rows R1 and R2, the performance on snow is remarkably deteriorated. However, in the first block row R1 and the second block row R2, the phase of the generation cycle of the deformation suppressing unit 6 is shifted in the tire circumferential direction, so that each of the block rows R1 and R2 has one lateral groove. Only one deformation suppressing portion 6 periodically provided every other portion appears in all the groove intersections G. That is, the deformation suppressing portions 6 are distributed in a well-balanced manner and arranged in the first and second block rows R1 and R2, so that the occurrence of uneven wear can be suppressed while minimizing the decrease in performance on snow.

  Here, according to the experiments by the inventors, in the case where each of the block rows R1 and R2 is provided with two deformation suppression portions 6, the uneven wear suppression effect is sufficiently exhibited in each of the block rows R1 and R2. It has been confirmed that it will not.

  Further, as described above, in the cross-shaped groove crossing portion G, the deformation suppressing portion 6 is provided only in any one of the facing lateral grooves 4a and 4b. For this reason, in the corner portion 5ae of one block 5a provided with the deformation suppressing portion 6, when the slip to the road surface is suppressed, the propagation of the slip to the corner portion 5be of the block 5b described above also occurs. Can be kept small. Thereby, the uneven wear of the corner portion is efficiently suppressed even for the block facing the lateral groove 4 where the deformation suppressing portion 6 is not provided.

  Here, since the center block 5a included in the first block row R1 closest to the tire equator C receives the greatest ground pressure, the slip on the road surface is smaller than the middle block 5b included in the second block row R2. Relatively small. For this reason, about the center block 5a, it is more effective to suppress the fall of on-snow performance than the improvement of uneven wear-proof performance. On the other hand, the middle block 5b arranged on the outer side in the tire axial direction of the center block 5a has a greater slippage with respect to the road surface due to a relative decrease in the contact pressure than the center block 5a. It is effective to relatively increase the wear performance.

  Further, since the performance on snow is greatly influenced by the groove width of the lateral groove 4, the tie bar 7 in the deformation suppressing portion 6, which does not substantially decrease the groove width of the lateral groove 4, has better performance on snow than the narrow portion 8. The decrease can be kept small.

  In view of the above, in the present embodiment, the central lateral groove 4a extending over the first block row R1 employs a tie bar 7 with a small decrease in performance on snow as the deformation suppressing portion 6, and the second block row R2 A narrow portion 8 is employed as the deformation suppressing portion 6 effective for uneven wear resistance in the extending intermediate lateral groove 4b. As a result, in the two block rows R1 and R2, the performance on snow and the resistance to uneven wear can be improved in a balanced manner.

  Furthermore, as shown in FIG. 3, the lateral groove 4a at the center of the first block row R1 is partially provided with a tie bar 7 on the tire equator side. Thereby, the central lateral groove 4a can secure a large depth on the second block row R2 side (that is, on the groove intersecting portion G side). In such a substantial form, when traveling on a snowy road, the snow column that has been compacted by the central lateral groove 4a tends to move toward the greater groove depth, and the groove intersection G has a high density and high rigidity. A cross-shaped snow column can be formed. Therefore, when this is sheared, a large driving force or braking force is obtained, and the performance on snow is further improved. In order to reliably achieve such an action, it is desirable that the tie bar 7 has at least the second block row R2 side portion 7b on which the raised height smoothly decreases.

  In the present embodiment, the outer lateral groove 4c that traverses the third block row R2 is inclined at a small angle of about 5 to 30 degrees with respect to the tire axial direction. The outer lateral groove 4c is inclined in the opposite direction to the central lateral groove 4a.

  In the present embodiment, the outer lateral groove 4c is provided at a position that does not oppose the intermediate lateral groove 4b via the outer longitudinal groove 3b. The definition of opposite is as described above. Accordingly, the respective openings of the outer lateral groove 4c and the intermediate lateral groove 4b that open at the outer longitudinal groove 3c do not have overlapping portions when projected onto a plane parallel to the tire equator. Since the shoulder block 5c inherently tends to cause uneven wear, it is preferable to prevent the alignment of the block corners on both sides of the outer longitudinal groove 3c and improve the uneven wear resistance performance by configuring as described above. .

  Further, as shown in FIG. 1, the pitch Pc in the tire circumferential direction of the siping S provided in the shoulder block 5c is formed larger than the pitch Pb in the tire circumferential direction of the siping S provided in the middle block 5b. . As a result, the rigidity of the shoulder block 5b, which is more slippery relative to the road surface than the middle block 5b, can be prevented from lowering the rigidity, thereby suppressing the occurrence of uneven wear. Further, the rigidity in the tire circumferential direction of the middle block 5b and the shoulder block 5c is made uniform, and uneven wear can be prevented from concentrating on the shoulder block 5b. Thus, in the pneumatic tire of this embodiment, the uneven wear resistance performance is improved over the entire block of the tread pattern.

  Here, the ratio (Pc / Pb) between the pitch Pc of the siping S in the shoulder block 5c and the pitch Pb of the siping S in the middle block 5b is not particularly limited, but if it is too small, the shoulder block 5c The uneven wear may concentrate on the middle block 5b. On the contrary, the uneven wear may concentrate on the middle block 5b. From such a viewpoint, the ratio (Pc / Pb) is preferably 1.1 or more, more preferably 1.2 or more, and the upper limit is preferably 1.5 or less, more preferably 1.3. The following is desirable. The pitches Pb and Pc are average values.

  In the present embodiment, the pitch Pa in the tire circumferential direction of the siping S of the center block 5a is determined to be substantially the same as that of the middle block 5b.

  The pitch Pc in the tire circumferential direction of the siping S of the shoulder block 5c is not particularly limited, but if it is too small, uneven wear tends to concentrate on the shoulder block 5c. There is a tendency that the effect of removing the water film decreases. From this point of view, the pitch Ps is preferably 2.5 mm or more, more preferably 3.0 mm or more, and the upper limit is preferably 6.0 mm or less, more preferably 5.0 mm or less.

  The number of sipings S provided in each block 5a to 5c is determined as appropriate based on the length of each block in the tire circumferential direction, the pitch of the siping S, and the like.

  Although the embodiments of the present invention have been described above, the present invention is applicable to various categories of pneumatic tires in addition to passenger car tires. Further, the present invention is not limited to the specific tread pattern described above, and can be applied to various specific tread patterns. For example, all of the deformation suppressing units 6 may be the tie bars 7, or all may be configured by the narrow portions 8. Moreover, the deformation | transformation suppression part 6 can include the tie bar 7 and the narrow part 8 in each block row | line | column.

(Tread pattern A)
A pneumatic radial tire (studless tire) of size 195 / 65R15 having the pattern shown in FIGS. 6 to 9 was prototyped and the following performance was tested. The common specifications of each part are as follows.
Tread width TW: 160mm
Groove width of the longitudinal grooves 3a to 3c: 6.8 mm
Groove depth of vertical grooves 3a-3c: 10.0mm
Groove width W1: 5.8 mm of the lateral grooves 4a to 4c
Groove depth d2 of the lateral grooves 4a to 4c: 10.0 mm
Angle of the central lateral groove 4a with respect to the tire circumferential direction: 90 degrees Angle of the intermediate lateral groove 4b with respect to the tire circumferential direction: 90 degrees Angle with respect to the tire circumferential direction of the outer lateral grooves 4c: 80 degrees Siping thickness: 0.5 mm
The angle of siping with respect to the tire axial direction: 0 degree Further, the test method is as follows.

<Performance on ice>
Each test tire was mounted on a 2000cc domestic four-wheel drive vehicle, and the braking distance was measured by applying full-lock sudden braking at a speed of 15km / h on an icy road at an air temperature of 0 ° C. The results were expressed as an index with the comparative example 1 being 100 with respect to the reciprocal of each braking distance. The larger the value, the better the performance on ice.

<Snow performance>
The test vehicle was run on a snowy road tire test course, and characteristics relating to steering response, rigidity, grip, etc. were evaluated based on the sensuality of professional drivers. The results are displayed as evaluation points with Comparative Example 1 as 100. The larger the value, the better the performance on snow.

<Abrasion resistance>
The test vehicle traveled 3000 km on a dry asphalt road surface, and the difference between the wear amount (average value) at both ends in the tire circumferential direction of the block and the wear amount at the center of the block was measured. The measurement was performed on three blocks on the tire circumference, and the average value was calculated. The results were expressed as an index with the value of Comparative Example 1 as 100 with respect to the reciprocal of each average value. The larger the value, the better the uneven wear resistance performance.
Table 1 shows the test results.

  As a result of the test, it was confirmed that the tires of the examples improved the wear resistance without deteriorating the running performance on snow and ice.

(Tread pattern B)
A pneumatic radial tire (studless tire) of size 195 / 65R15 having the substantially point-symmetric pattern of FIGS. 1 and 10 was prototyped based on the specifications in Table 2, and the same performance as above was tested. The common specifications of each part are as follows.
Tread width TW: 160mm
Groove width of the longitudinal grooves 3a to 3c: 5.0 mm (average)
Groove depth of vertical grooves 3a-3c: 10.0mm
Groove width W1 of lateral grooves 4a to 4c: 5.0 mm (average)
Groove depth d2 of the lateral grooves 4a to 4c: 10.0 mm
Angle of the central lateral groove 4a with respect to the tire circumferential direction: 70 degrees Angle of the intermediate lateral groove 4b with respect to the tire circumferential direction: 75 degrees, 85 degrees V-shaped angle with respect to the tire circumferential direction of the outer lateral grooves 4c: 80 degrees Test results, etc. Is shown in Table 2.

  As a result of the test, it was confirmed that the tires of the examples improved the wear resistance without deteriorating the running performance on snow and ice.

It is an expanded view of the tread pattern which shows embodiment of this invention. (A) is a partially enlarged view thereof, and (B) is a projection view showing an opening of a lateral groove projected onto the projection plane VP. (A) is the elements on larger scale, (B) is the AA expanded sectional view. (A) and (B) are BB expanded sectional views of Drawing 3 (B). It is the elements on larger scale of the tread pattern explaining a narrow part. It is an expanded view of the tread pattern of an Example. It is an expanded view of the tread pattern of an Example. It is an expanded view of the tread pattern of an Example. 6 is a development view of a tread pattern of Comparative Example 1. FIG. 6 is a development view of a tread pattern of Comparative Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Vertical groove 3a Center vertical groove 3b Middle vertical groove 3c Outer vertical groove 4 Horizontal groove 4a Central horizontal groove 4b Middle horizontal groove 4c Outer horizontal groove 5a Center block 5b Middle block 5c Shoulder block 6 Deformation Suppression part 7 Tie bar 8 Narrow part

Claims (6)

A pneumatic structure in which a first block row and a second block row are arranged on both sides of one longitudinal groove extending continuously in the tire circumferential direction on the tread portion, and blocks divided by the lateral grooves are arranged in the tire circumferential direction. Tire,
Each block of the first and second block rows is formed with a plurality of sipings extending in the tire axial direction,
The horizontal groove of the first block row and the horizontal groove of the second block row are opened at positions substantially opposed to each other through the vertical groove, and the first block row and the second block row The horizontal groove is provided with a deformation suppressing portion that suppresses deformation in the tire circumferential direction of the block facing the horizontal groove,
The deformation suppression unit is arranged in a zigzag manner across the longitudinal grooves by being arranged alternately in the tire circumferential direction in each block row and shifting its phase in the tire circumferential direction. Enter tire.   2. The pneumatic tire according to claim 1, wherein the deformation suppressing portion is a tie bar in which the groove depth of the transverse groove is reduced by raising the groove bottom and / or a narrow portion in which the groove width of the transverse groove is partially reduced.   3. The pneumatic tire according to claim 2, wherein in the lateral groove of the first block row, the deformation suppressing portion is formed of the tie bar, and in the second block row, the deformation suppressing portion is formed of a narrow portion.   The pneumatic tire according to claim 3, wherein the first block row is disposed at a position closest to the tire equator, and the second block row is disposed on the outer side in the tire axial direction.   The pneumatic tire according to claim 4, wherein the lateral groove of the first block row has a large depth on the second block row side when the tie bar is provided on the tire equator side. The tread portion has a third block row on the outer side in the tire axial direction of the second block row, in which blocks each divided by a lateral groove and provided with a plurality of sipings are arranged in the tire circumferential direction,
The lateral groove of the third block row is provided at a position not facing the lateral groove of the second block row,
The pitch in the tire circumferential direction of siping provided in the blocks in the third block row is larger than the pitch in the tire circumferential direction of siping provided in the blocks in the second block row. Pneumatic tires.

Images