JP2010018126A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of ensuring wet performance of the tire while improving the rib-tear resistance performance and uneven wear resistance of the tire. <P>SOLUTION: In this pneumatic tire, amplitude As of a zigzag shape of a shoulder peripheral direction main groove 22 and amplitude Ac of the zigzag shape of a center peripheral direction main groove 21 have the following relationship; 0.3≤As/Ac≤0.7. The shoulder peripheral direction main groove 22 is constituted by a plurality of narrow grooves 221 extended to the tire peripheral direction, and a narrow rib 222 partitioned by the narrow grooves 221. The narrow rib 222 closes a see-through part of the shoulder peripheral direction main groove 22. A groove width Ws of the narrow groove 221 and a groove width Wc of the center peripheral direction main groove 21 have the following relationship; 0.3≤Ws/Wc≤0.7. A rib width Wr of the narrow rib 222 and a groove width Ws of the narrow groove 221 have the following relationship; 1.0≤Wr/Ws≤3.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can ensure wet performance of a tire while improving the rib tear performance and uneven wear resistance performance of the tire.

  In recent pneumatic tires, in a configuration having a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of ribs defined by these circumferential main grooves, the center circumferential main groove and the shoulder circumferential direction The main groove has a groove shape extending in a zigzag shape in the tire circumferential direction. Such a configuration is preferable in that the rib tear is reduced. As a conventional pneumatic tire related to such a problem, a technique described in Patent Document 1 is known.

JP 2001-187519 A

  On the other hand, in a pneumatic tire, there exists a subject which should make the rib tear performance, uneven wear-proof performance, and wet performance of a tire compatible.

  Therefore, the present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire that can ensure the wet performance of the tire while improving the rib tear performance and uneven wear resistance performance of the tire.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of land portions defined by the circumferential main grooves. The circumferential main groove disposed in the tread portion center region is referred to as a center circumferential main groove, and the circumferential main groove disposed in the tread portion shoulder region is referred to as a shoulder circumferential main. When the groove 22 is called, the center circumferential main groove and the shoulder circumferential main groove have a groove shape extending in a zigzag shape in the tire circumferential direction, and the zigzag amplitude As of the shoulder circumferential main groove and A zigzag amplitude Ac of the center circumferential main groove has a relationship of 0.3 ≦ As / Ac ≦ 0.7, and the shoulder circumferential main groove extends in the tire circumferential direction. And the thin ribs defined by the narrow grooves, the thin ribs are disposed so as to close the see-through portions of the shoulder circumferential main grooves, and the groove width Ws of the narrow grooves and the center circumferential main The groove width Wc has a relationship of 0.3 ≦ Ws / Wc ≦ 0.7, and the rib width Wr of the fine rib and the groove width Ws of the fine groove are 1.0 ≦ Wr / Ws. It has a relationship of ≦ 3.0.

  In this pneumatic tire, (1) since the center circumferential main groove and the shoulder circumferential main groove have a groove shape extending in a zigzag shape in the tire circumferential direction, entry of foreign matter into the shoulder circumferential main groove is reduced. Thus, there is an advantage that the tire's rib tear resistance performance is improved. At this time, the relationship between the zigzag amplitude As of the shoulder circumferential main groove and the zigzag amplitude Ac of the center circumferential main groove is optimized (0.3 ≦ As / Ac ≦ 0.7). There is an advantage that uneven wear of the rib can be reduced. Further, (2) the shoulder circumferential main groove is composed of a plurality of narrow grooves extending in the tire circumferential direction and thin ribs defined by these narrow grooves, and the groove width Ws of the narrow groove and the center The groove width Wc of the circumferential main groove is optimized (0.3 ≦ Ws / Wc ≦ 0.7). By making the shoulder circumferential main groove into a plurality of narrow grooves and satisfying 0.3 ≦ Ws / Wc ≦ 0.7, the thin rib is arranged in the shoulder circumferential main groove, while the groove width Ws of the narrow groove is It is optimized. Thereby, there is an advantage that the groove area of the tread portion is appropriately secured and the wet performance of the tire is secured. (3) Since the thin rib blocks the see-through portion of the shoulder circumferential main groove, a circumferential main groove that is not in communication with the tire circumferential direction is formed. As a result, the intrusion of foreign matter into the shoulder circumferential main groove is effectively reduced, and there is an advantage that the rib tear resistance performance of the tire is further improved. At this time, since the relation between the rib width Wr of the fine rib and the groove width Ws of the fine groove is optimized (1.0 ≦ Wr / Ws ≦ 3.0), the rigidity of the fine rib is ensured and the fine rib is secured. There is an advantage that the tier is reduced.

  In the pneumatic tire according to the present invention, the zigzag pitch Ps of the shoulder circumferential main groove and the zigzag pitch Pc of the center circumferential main groove satisfy 0.3 ≦ Ps / Pc ≦ 0.7. Have a relationship.

  In this pneumatic tire, the zigzag pitch Ps of the shoulder circumferential main groove is set smaller than the zigzag pitch Pc of the center circumferential main groove (0.3 ≦ Ps / Pc ≦ 0.7). There is an advantage that the tear of the shoulder rib in the shoulder circumferential main groove is reduced.

  In the pneumatic tire according to the present invention, a region of TDW / 2 centered on the tire equator plane with respect to the tread development width TDW is defined as a tread portion center region, and the remaining region is defined as a tread portion shoulder region. In addition, the groove area ratio Gc of the tread portion center region and the groove area ratio Gs of the tread portion shoulder region have a relationship of 0.8 ≦ Gs / Gc ≦ 1.2.

  In this pneumatic tire, since the groove area ratio Gc of the tread portion center region and the groove area ratio Gs of the tread portion shoulder region are substantially equal, there is an advantage that the uneven wear resistance performance and the wet performance of the tire are ensured.

  In the pneumatic tire according to the present invention, (1) the center circumferential main groove and the shoulder circumferential main groove have a groove shape extending in a zigzag shape in the tire circumferential direction, so that foreign matter enters the shoulder circumferential main groove. There is an advantage that the rib tear resistance performance of the tire is improved. At this time, the relationship between the zigzag amplitude As of the shoulder circumferential main groove and the zigzag amplitude Ac of the center circumferential main groove is optimized (0.3 ≦ As / Ac ≦ 0.7). There is an advantage that uneven wear of the convex portion of the rib is reduced. Further, (2) the shoulder circumferential main groove is composed of a plurality of narrow grooves extending in the tire circumferential direction and thin ribs defined by these narrow grooves, and the groove width Ws of the narrow groove and the center The groove width Wc of the circumferential main groove is optimized (0.3 ≦ Ws / Wc ≦ 0.7). By making the shoulder circumferential main groove into a plurality of narrow grooves and satisfying 0.3 ≦ Ws / Wc ≦ 0.7, the thin rib is arranged in the shoulder circumferential main groove, while the groove width Ws of the narrow groove is It is optimized. Thereby, there is an advantage that the groove area of the tread portion is appropriately secured and the wet performance of the tire is secured. (3) Since the thin rib blocks the see-through portion of the shoulder circumferential main groove, a circumferential main groove that is not in communication with the tire circumferential direction is formed. As a result, the intrusion of foreign matter into the shoulder circumferential main groove is effectively reduced, and there is an advantage that the rib tear resistance performance of the tire is further improved. At this time, since the relation between the rib width Wr of the fine rib and the groove width Ws of the fine groove is optimized (1.0 ≦ Wr / Ws ≦ 3.0), the rigidity of the fine rib is ensured and the fine rib is secured. There is an advantage that the tier is reduced.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an explanatory view showing a modification of the pneumatic tire shown in FIG. FIG. 3 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

[Pneumatic tire]
The pneumatic tire (pneumatic radial tire) 1 includes a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction, and a plurality of land portions defined by the circumferential main grooves 21 and 22 ( Ribs) 31 and 32 are provided in the tread portion (see FIG. 1). Here, the circumferential main groove 21 disposed in the tread portion center region is referred to as a center circumferential direction main groove, and the circumferential main groove 22 disposed in the tread portion shoulder region is referred to as a shoulder circumferential direction main groove 22. For example, in this embodiment, a single center circumferential main groove 21 is disposed along the tire equator line CL, and one shoulder circumferential main groove 22 is provided in the shoulder region of the tread on the left and right sides of the tire. Is arranged. Therefore, a total of three circumferential main grooves 21 and 22 are arranged in the tread portion. A pair of center ribs 31, 31 are defined by the center circumferential main groove 21 and the pair of shoulder circumferential main grooves 22, 22, and each shoulder circumferential main groove 22, 22 and the tread portion Shoulder ribs 32 and 32 are formed respectively by the end portions. Thereby, the rib pattern is formed in the tread portion.

  Further, the center circumferential main groove 21 and the shoulder circumferential main groove 22 have a groove shape extending in a zigzag shape in the tire circumferential direction in plan view of the tread portion (see FIG. 1). At this time, the zigzag amplitude As of the shoulder circumferential main groove 22 and the zigzag amplitude Ac of the center circumferential main groove 21 have a relationship of 0.3 ≦ As / Ac ≦ 0.7. The circumferential main grooves 21 and 22 may have a substantially zigzag shape as a whole in a plan view of the tread portion, and a notch portion or a sipe or the like is formed on the edge portion of the tread surface of the land portions 31 and 32. You may have (illustration omitted).

  The amplitude Ac of the center circumferential main groove 21 and the amplitude As of the shoulder circumferential main groove 22 can be appropriately selected depending on the tire specifications and the like. Generally, if the amplitude of the circumferential main groove is too large, riverware is likely to occur in the circumferential main groove.

  It should be noted that the amplitude Ac of the center circumferential main groove 21 and the amplitude As of the shoulder circumferential main groove 22 are set perpendicular to the flat plate in a no-load state while the tire is mounted on the applicable rim and a prescribed internal pressure is applied. This is the dimension at the contact surface between the tire and the flat plate when it is placed.

  Here, the applicable rim means “applied rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. The normal internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in the case of a tire for a passenger car, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  The shoulder circumferential main groove 22 includes a plurality of fine grooves 221 and 221 extending in the tire circumferential direction and fine ribs 222 defined by the fine grooves 221 and 221 (see FIG. 1). ). For example, in this embodiment, the shoulder circumferential main groove 22 is constituted by a pair of narrow grooves 221 and 221 extending in the tire circumferential direction and a single thin rib 222 sandwiched between the narrow grooves 221 and 221. Has been. Further, the pair of narrow grooves 221 and 221 extend in a zigzag shape in the tire circumferential direction, and form left and right groove walls (zigzag-shaped outer shape) of the shoulder circumferential main groove 22. Further, the thin ribs 222 defined by the thin grooves 221 and 221 have a zigzag shape (zigzag shape extending in the tire circumferential direction) along the shape of the shoulder circumferential main groove 22. That is, the shoulder circumferential main groove 22 is as if one thin rib 222 is arranged on the groove center line of a general circumferential main groove (for example, the center circumferential main groove 21 shown in FIG. 1). It has a configuration.

  In the shoulder circumferential main groove 22, the thin ribs 222 are arranged so as to close the see-through portion of the shoulder circumferential main groove 22 (see FIG. 1). The see-through portion refers to a portion that does not communicate in the circumferential direction where there is no open space in the circumferential direction. For example, in this embodiment, one thin rib 222 extends in a zigzag shape in the tire circumferential direction on the groove center line of the shoulder circumferential main groove 22, so that the see-through portion of the shoulder circumferential main groove 22 is formed. Is blocking. By arranging the thin rib 222, the amplitude As of the shoulder circumferential main groove 22 (the amplitude of the narrow groove 221) can be reduced, and the river wear is reduced. In addition, the intrusion of foreign matter into the groove is reduced, and the rib tear resistance performance of the tire is improved.

  In the shoulder circumferential main groove 22, the groove width Ws of the narrow groove 221 and the groove width Wc of the center circumferential main groove 21 have a relationship of 0.3 ≦ Ws / Wc ≦ 0.7. The groove width Ws of the narrow groove 221 and the groove width Wc of the center circumferential main groove 21 may be different from each other as long as this relationship is satisfied.

  The groove width Wc of the center circumferential main groove and the groove width Ws of the narrow groove are determined when the tire is mounted on the applicable rim and applied with a specified internal pressure and placed perpendicular to the flat plate in an unloaded state. The dimension at the contact surface between the tire and the flat plate.

  Further, the rib width Wr of the fine rib 222 and the groove width Ws of the fine groove 221 have a relationship of 1.0 ≦ Wr / Ws ≦ 3.0. Thereby, the relationship between the rib width Wr of the fine rib 222 and the groove width Ws of the fine groove 221 in the shoulder circumferential main groove 22 is optimized.

  In this pneumatic tire 1, only the shoulder circumferential main grooves 22, 22 have the thin ribs 222 that block the see-through portion. However, the present invention is not limited to this, and the center circumferential main groove 21 has the same thin ribs. You may have (illustration omitted).

  The groove width Wc of the center circumferential main groove 21 is preferably in the range of 4 [%] to 8 [%] with respect to the tread development width TDW of the tire (see FIG. 1). In addition, the amplitude Ac of the center circumferential main groove 21 is preferably in the range of 5 [%] to 15 [%] with respect to the tread development width TDW of the tire. Thereby, the general function of a tire is ensured appropriately.

  The tread development width TDW refers to a linear distance between both ends (ground contact ends) of the tread pattern portion of the tire when the tire is mounted on the applicable rim and applied with a specified internal pressure and is not loaded.

  Further, the groove depth of the narrow groove 221 of the shoulder circumferential main groove 22 may be the same as or shallower than the groove depth of the center circumferential main groove 21.

[effect]
In this pneumatic tire 1, (1) the center circumferential main groove 21 and the shoulder circumferential main groove 22 have a groove shape extending in a zigzag shape in the tire circumferential direction. There is an advantage that the invasion is reduced and the rib tear resistance performance of the tire is improved. At this time, the relationship between the zigzag amplitude As of the shoulder circumferential main groove 22 and the zigzag amplitude Ac of the center circumferential main groove 21 is optimized (0.3 ≦ As / Ac ≦ 0.7). There is an advantage that uneven wear of the convex portion of the shoulder rib is reduced. For example, when the groove widths are the same, there is a problem that rib tears occur when As / Ac <0.3, and uneven wear occurs at the convex portions of the shoulder ribs when 0.7 <As / Ac. There's a problem.

  (2) The shoulder circumferential main groove 22 is constituted by a plurality of fine grooves 221 and 221 extending in the tire circumferential direction, and fine ribs 222 defined by the fine grooves 221 and 221; and The ratio Ws / Wc between the groove width Ws of the narrow groove 221 and the groove width Wc of the center circumferential main groove 21 is optimized (0.3 ≦ Ws / Wc ≦ 0.7). Therefore, the narrow rib 222 is disposed in the shoulder circumferential main groove 22 while the groove width Ws of the narrow groove 221 is optimized. Thereby, there is an advantage that the groove area of the tread portion is appropriately secured and the wet performance of the tire is secured. For example, if Ws / Wc <0.3, the groove area of the tread shoulder region is insufficient, and the wet performance of the tire may be reduced. On the other hand, if 0.7 <Ws / Wc, there is a problem that rib tears are likely to occur.

  (3) Since the thin rib 222 closes the see-through portion of the shoulder circumferential main groove 22, a circumferential main groove that is not in communication with the tire circumferential direction is formed. As a result, the intrusion of foreign matter into the shoulder circumferential main groove 22 is effectively reduced, and there is an advantage that the rib tear resistance performance of the tire is further improved. At this time, since the relation between the rib width Wr of the fine rib and the groove width Ws of the fine groove is optimized (1.0 ≦ Wr / Ws ≦ 3.0), the rigidity of the fine rib 222 is ensured and thin. There is an advantage that the tear of the rib 222 is reduced. For example, if Wr / Ws <1.0, the rigidity of the thin ribs is insufficient, and there is a possibility that tearing occurs in the thin ribs. On the other hand, when 3.0 <Wr / Ws, there is a problem that the width of adjacent ribs becomes small, and rib tears and uneven wear are likely to occur due to a decrease in rigidity.

[Modification]
In the pneumatic tire 1 shown in FIG. 1, the zigzag pitch Ps of the shoulder circumferential main groove 22 and the zigzag pitch Pc of the center circumferential main groove 21 are set to be the same (Ps = Pc). Yes.

  However, the pneumatic tire 1 is not limited thereto, and the zigzag pitch Ps of the shoulder circumferential main groove 22 and the zigzag pitch Pc of the center circumferential main groove 21 are 0.3 ≦ Ps / Pc ≦. It may have a relationship of 0.7 (see FIG. 2). In general, in the circumferential main groove, the smaller the zigzag pitch is, the less foreign material enters the groove. Therefore, when the zigzag pitch Ps of the shoulder circumferential main groove 22 is set smaller than the zigzag pitch Pc of the center circumferential main groove 21 (0.3 ≦ Ps / Pc ≦ 0.7), the shoulder There is an advantage that the tear of the thin rib 222 in the circumferential main groove 22 is reduced.

  Further, in the pneumatic tire 1, a region of TDW / 2 centered on the tire equatorial plane CL with respect to the tread development width TDW is defined as a tread portion center region, and the remaining region is defined as a tread portion shoulder region (see FIG. 2). At this time, it is preferable that the groove area ratio Gc of the tread portion center region and the groove area ratio Gs of the tread shoulder region have a relationship of 0.8 ≦ Gs / Gc ≦ 1.2. In such a configuration, the groove area ratio Gc of the tread portion center region and the groove area ratio Gs of the tread portion shoulder region are substantially equal, and therefore there is an advantage that the uneven wear resistance performance and the wet performance of the tire are ensured.

  In the above configuration, the groove area ratio Gc of the tread center region and the groove area ratio Gs of the tread shoulder region are preferably both in the range of 20 [%] to 30 [%]. This ensures the general performance of the tire.

[performance test]
In this example, performance tests regarding (1) rib tear resistance performance, (2) uneven wear resistance performance, and (3) wet performance were performed on a plurality of pneumatic tires having different conditions (see FIG. 3). In this performance test, a pneumatic tire having a tire size of 11R22.5 is assembled to a rim having a rim size of 22.5 × 7.50, and a pneumatic pressure of 700 [kPa] and a load of 26.72 [kN] are applied to the pneumatic tire. The

  (1) In the performance test related to the anti-rib tear performance, a pneumatic tire is mounted on the front shaft of the test vehicle, and the test vehicle rides on a curb with a height of 200 mm while turning. Then, the number of occurrences of tiers when the number of times the test vehicle rides on the curb is 20 is observed. Then, based on the observation result, index evaluation using the conventional example as a reference (100) is performed. The larger this value is, the more preferable it is.

  (2) In the performance test related to uneven wear resistance, a pneumatic tire is mounted on the front shaft of the test vehicle, and the test vehicle travels on a paved road for 50,000 [km]. And the partial wear which generate | occur | produced in the center land part and the shoulder land part after driving | running | working is observed. Based on this observation result, index evaluation is performed with the conventional example as a reference (100). An evaluation result is so preferable that the numerical value is large.

  (3) In the performance test relating to wet performance, a test vehicle equipped with a pneumatic tire travels on a wet road surface (a flooded asphalt road surface), and a braking distance from an initial speed of 40 [km / h] is measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. An evaluation result is so preferable that the numerical value is large.

  The pneumatic tire of the conventional example has a groove shape in which the center circumferential main groove and the shoulder circumferential main groove extend in a zigzag shape in the tire circumferential direction, and the zigzag amplitude As of the shoulder circumferential main groove and The zigzag amplitude Ac of the center circumferential main groove has a relationship of As / Ac = 0.8. Further, the shoulder circumferential main groove has a single structure (one circumferential groove). The ratio of the groove width of the shoulder circumferential main groove to the groove width of the center circumferential main groove is set to 0.8.

  In the pneumatic tires 1 of Invention Examples 1 to 3, the center circumferential main groove 21 and the shoulder circumferential main groove 22 have a groove shape extending in a zigzag shape in the tire circumferential direction, and the shoulder circumferential main groove 22. The ratio As / Ac of the zigzag amplitude As of the center and the zigzag amplitude Ac of the center circumferential main groove 21 is in the range of 0.3 ≦ As / Ac ≦ 0.7 (see FIG. 1). Further, the shoulder circumferential main groove 22 is constituted by a pair of narrow grooves 221 and 221 extending in the tire circumferential direction and thin ribs 222 defined by these narrow grooves 221 and 221. That is, the shoulder circumferential main groove 22 is composed of two narrow grooves 221 and 221. Further, the thin rib 222 is disposed so as to close the see-through portion of the shoulder circumferential main groove 22, and the ratio Ws / Wc between the groove width Ws of the narrow groove 221 and the groove width Wc of the center circumferential main groove 21 is It is in the range of 0.3 ≦ Ws / Wc ≦ 0.7 (Ws / Wc = 0.5). Further, the rib width Wr of the fine rib 222 and the groove width Ws of the fine groove 221 have a relationship of 1.0 ≦ Wr / Ws ≦ 3.0.

  As shown in the test results, it can be seen that in the pneumatic tires 1 to 3 of the invention examples, the tire's rib tear performance and uneven wear resistance performance are improved, and the tire's wet performance is ensured (Fig. 3). Further, comparing Invention Example 1 and Invention Example 2, the ratio As / Ac between the zigzag amplitude As of the shoulder circumferential main groove 22 and the zigzag amplitude Ac of the center circumferential main groove 21 is optimized. This shows that the uneven wear resistance performance of the tire is improved. Further, when Invention Example 2 and Invention Example 3 are compared, the ratio Ps / Pc between the zigzag pitch Ps of the shoulder circumferential main groove 22 and the zigzag pitch Pc of the center circumferential main groove 21 is optimized. It can be seen that the rib tear performance of the tire is further improved.

  As described above, the pneumatic tire according to the present invention is useful in that the wet performance of the tire can be ensured while improving the rib tear performance and uneven wear resistance performance of the tire.

It is a top view which shows the tread surface of the pneumatic tire concerning the Example of this invention. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 21 Center circumferential main groove 22 Shoulder circumferential main groove 31 Center rib 32 Shoulder rib 221 Narrow groove 222 Narrow rib

Claims (3)

A pneumatic tire having a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of land portions defined by the circumferential main grooves in a tread portion,
When the circumferential main groove arranged in the tread portion center region is called a center circumferential main groove and the circumferential main groove arranged in the tread portion shoulder region is called a shoulder circumferential main groove 22.
The center circumferential main groove and the shoulder circumferential main groove have a groove shape extending in a zigzag shape in the tire circumferential direction, and the zigzag amplitude As of the shoulder circumferential main groove and the center circumferential main groove The zigzag amplitude Ac has a relationship of 0.3 ≦ As / Ac ≦ 0.7, and the shoulder circumferential main groove is partitioned by a plurality of narrow grooves extending in the tire circumferential direction and the narrow grooves. The narrow ribs are arranged so as to close the see-through portion of the shoulder circumferential main groove, and the groove width Ws of the narrow groove and the groove width Wc of the center circumferential main groove are 0. 3 ≦ Ws / Wc ≦ 0.7, and the rib width Wr of the fine rib and the groove width Ws of the fine groove have a relationship of 1.0 ≦ Wr / Ws ≦ 3.0. A pneumatic tire characterized by that.   The pneumatic according to claim 1, wherein the zigzag pitch Ps of the shoulder circumferential main groove and the zigzag pitch Pc of the center circumferential main groove have a relationship of 0.3≤Ps / Pc≤0.7. tire.   When the region of TDW / 2 centered on the tire equatorial plane with respect to the tread development width TDW is defined as the tread portion center region and the remaining region is defined as the tread portion shoulder region, the groove area ratio Gc of the tread portion center region The pneumatic tire according to claim 1 or 2, wherein the groove area ratio Gs of the shoulder region of the tread part has a relationship of 0.8≤Gs / Gc≤1.2.

Images