JP4285617B2 - Pneumatic radial tire - Google Patents

Description

【００４４】
表１より、周方向溝及び斜め溝の溝深さが同じ比較例１のタイヤと比較して、実施例タイヤはいずれもタイヤ騒音の悪化を抑えながら湿潤路排水性能及び乾燥路操縦安定性能が良好であることを示している。特に、周方向溝の溝深さＤが斜め溝の溝深さｄの５０％〜８５％までのタイヤ（Ｄ／ｄが０．５〜０．８５）の場合、比較例１タイヤと比較してタイヤ騒音を低減しながら湿潤路排水性能及び乾燥路操縦安定性能が向上している。
【００４５】
また、上記周方向溝の溝幅が４ｍｍ未満の比較例４タイヤの場合、ブロック剛性が高くなってタイヤ騒音及び排水性が悪化しており、また接地幅比が１５％を超える比較例５タイヤの場合は、周方向溝に沿ってバックリングが発生し易くなり、乾燥路面における操縦安定性が低下している。
【００４６】
【発明の効果】
以上の通り、本発明の空気入りラジアルタイヤは、タイヤトレッド面に、タイヤ赤道付近からタイヤショルダー端にまで延びる斜め溝と、この斜め溝に交差してタイヤ周方向に延びる周方向溝を有する空気入りラジアルタイヤにおいて、
上記周方向溝は溝幅が４ｍｍ以上で且つ接地幅の１５％以内であり、
上記周方向溝の溝深さが上記斜め溝の溝深さより浅く且つ上記斜め溝の溝深さの５０〜８５％に設定され、
上記周方向溝と上記斜め溝の交点での溝深さは当該斜め溝の溝深さであり、
上記斜め溝はタイヤ赤道付近から両接地端にかけて小さな傾斜角から大きな傾斜角へ傾斜角が変化し、ショルダー部の角度変化がセンター部及びメディエイト部での角度変化より大きい構成であり、
上記周方向溝が少なくとも片側のショルダー部に配置されている空気入りラジアルタイヤであるので、タイヤ騒音の低減を図りつつ、湿潤路面における排水性と乾燥路面における操縦安定性の向上を同時に図ることができる。
【図面の簡単な説明】
【図１】本発明に係る空気入りラジアルタイヤの一実施形態を示すトレッドパターンの概略展開図である。
【図２】同他実施形態を示すトレッドパターンの概略展開図である。
【図３】同他実施形態を示すトレッドパターンの概略展開図である。
【図４】タイヤの回転方向を持たない同他実施形態を示すトレッドパターンの概略展開図である。
【図５】非対称パターンで構成された同他実施形態を示すトレッドパターンの概略展開図である。
【図６】図１におけるタイヤの概略断面図である。
【符号の説明】
１ タイヤトレッド部
２ 斜め溝
３ 斜め溝
４ 接地端
５ 接地端
６ 周方向溝
７ 周方向溝
８ ショルダーブロック
９ ショルダーブロック
１０ 横溝
１１ 横溝
１２ 周方向溝
１３ 周方向溝
１４ メディエイトブロック
１５ メディエイトブロック
１６ 周方向溝
１７ 斜め溝
１８ センターブロック
１９ センターブロック
２０ 斜め溝
２１ ショルダーブロック
２２ 斜め溝
２３ 周方向溝
２４ 横溝
２５ ショルダーブロック
ＳＨ タイヤショルダー部
ＳＥ タイヤショルダー端[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic radial tire provided with a block pattern, and particularly to a technique for improving drainage performance on a wet road surface and steering stability on a dry road surface while reducing tire noise.
[0002]
[Prior art]
Conventionally, in order to reduce tire noise while ensuring drainage performance on wet road surfaces, circumferential grooves having the same or deeper groove depths are formed on the tire tread surface from the vicinity of the tire equator to the tire shoulder end. At least in the tire shoulder portion, the block rigidity of the tire shoulder portion is reduced, the impact sound generated when the block hits the road surface is suppressed, and furthermore the block shape is the same, resulting in the placement of the deformed block Tires that suppress the occurrence of pattern noise are provided.
[0003]
[Problems to be solved by the invention]
However, in the case of a tire in which the tire shoulder portion has the same block shape by a circumferential groove section that is the same as or deeper than the oblique groove, when the tire is subjected to a high load during traveling, the circumference that defines the block is defined. Since the so-called buckling in which the edge of the block floats along the directional groove is likely to occur, and the circumferential groove is formed with the same or deeper groove depth than the oblique groove, the tire shoulder block It is not necessarily preferable in terms of steering stability on a dry road surface due to excessively low rigidity.
[0004]
On the other hand, an oblique groove extending from the tire equator to the tire shoulder end is disposed on the tire tread surface, and a large block defined by the oblique groove and the oblique groove adjacent to each other in the tire circumferential direction is substantially disposed near the tire shoulder. There is also provided a tire having a lateral groove extending upward. Since such a tire has no circumferential groove on the tire tread surface, even when a heavy load is applied to the tire during traveling, buckling that occurs along the circumferential groove like the tire described above is suppressed. This makes it possible to increase the block rigidity and ensure the steering stability.
[0005]
However, in the case of such a tire, in order to suppress a striking sound generated when a large block partitioned between adjacent oblique grooves hits the road surface, it is often a pattern in which a shoulder block is formed by dividing by a lateral groove, and different blocks The configuration is such that the shape is arranged in the circumferential direction in the tire shoulder portion, and pattern noise due to the arrangement of the deformed blocks tends to occur during traveling, which is not necessarily preferable in terms of preventing tire noise. In addition, step wear may occur in the shoulder block.
[0006]
An object of the present invention is to provide a pneumatic radial tire that can simultaneously improve drainage performance on wet road surfaces and steering stability on dry road surfaces while reducing tire noise.
[0007]
[Means for Solving the Problems]
The present invention provides a pneumatic radial tire having a diagonal groove extending from the vicinity of the tire equator to the tire shoulder end on the tire tread surface and a circumferential groove extending in the tire circumferential direction intersecting the diagonal groove.
The circumferential groove has a groove width of 4 mm or more and within 15% of the ground contact width,
The groove depth of the circumferential groove is set to be less than the groove depth of the oblique groove and 50 to 85% of the groove depth of the oblique groove,
The groove depth at the intersection of the circumferential groove and the oblique groove is the groove depth of the oblique groove,
The oblique groove has a structure in which the inclination angle changes from a small inclination angle to a large inclination angle from the vicinity of the tire equator to both contact ends, and the angle change of the shoulder portion is larger than the angle change in the center portion and the mediate portion ,
A pneumatic radial tire characterized in that the circumferential groove is disposed at least on one side of the tire shoulder.
[0008]
As described above, the tire of the present invention has the oblique groove extending from the vicinity of the tire equator to the tire shoulder end, and the circumferential groove extending in the tire circumferential direction intersecting the oblique groove, so that only the oblique groove is provided. Compared with tires that are configured with the above, because of the pattern configuration, block rigidity can be reduced by forming circumferential grooves and diagonal grooves, thereby reducing the impact sound that occurs when the block contacts the road surface can do.
[0009]
Further, the tire according to the present invention is different from a tire in which a large block partitioned between adjacent oblique grooves as described above is divided into transverse grooves to form a shoulder block, and the tire is formed by the partition between the oblique grooves and the circumferential grooves. The blocks adjacent to each other in the circumferential direction can have the same block shape, and it is possible to prevent the occurrence of pattern noise due to the arrangement of irregular blocks such as conventional tires.
[0010]
In addition, the tire according to the present invention is set along the circumferential groove by adjusting the groove depth of the circumferential groove because the groove depth of the circumferential groove is set to be shallower than the groove depth of the oblique groove. Easy buckling of the block edge can be suppressed. Moreover, the tire of this invention can suppress the fall of the block rigidity which went too much by the division by this shallow circumferential groove | channel compared with the tire which made the groove depth of the circumferential groove | channel equal or deeper than the diagonal groove | channel. Therefore, the tire of the present invention can also ensure steering stability with respect to a dry road surface.
[0011]
Particularly in the tire of the present invention, the groove depth of the circumferential groove is 50 to 85% of the groove depth of the oblique groove. This is because, when the groove depth of the circumferential groove is less than 50% of the groove depth of the oblique groove, the drainage performance on the wet road surface is deteriorated, and the block rigidity is increased and the tire noise is deteriorated. When the groove depth of the circumferential groove exceeds 85% of the groove depth of the oblique groove, the buckling of the block edge portion easily occurs along the circumferential groove, and the steering stability on the dry road surface Decreases.
[0012]
Moreover, in the tire of the present invention, the groove width of the circumferential groove is 4 mm or more and the groove width is within 15% of the ground contact width (distance between both ground contact ends). This is because, when the groove width of the circumferential groove is less than 4 mm, the block rigidity becomes high and the tire noise is deteriorated. However, when the contact width ratio exceeds 15%, the back along the circumferential groove is increased. This is because a ring is likely to be generated and steering stability on a dry road surface is lowered. The range of the groove width of the circumferential groove is a value under the condition that the ratio of all grooves in the tire tread portion is made constant by adjusting the groove width of the oblique grooves or the number of circumferential grooves.
[0013]
Further, in the tire of the present invention, the groove depth at the intersection of the circumferential groove and the oblique groove is configured as the groove depth of the oblique groove. Thereby, in addition to sufficiently ensuring drainage by the above-mentioned oblique grooves, drainage is also secured in the circumferential grooves, so that the drainage is improved as a whole.
[0014]
In all the configurations described above, the inclination angle of the oblique groove changes from a small inclination angle to a large inclination angle from the vicinity of the tire equator to both contact ends, and the angle change of the shoulder portion is more than the angle change in the center portion and the mediate portion. It can be most suitably applied to a tire having a large configuration. Further, by disposing the circumferential groove on at least one tire shoulder, it is possible to improve drainage on wet road surfaces and steering stability on dry road surfaces while reducing tire noise.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic radial tire according to the present invention.
[0016]
In the figure, 1 is a tire tread portion, and 2 and 3 are tire tread surfaces that are not connected to each other from the vicinity of the tire equator EQ and extend to both ground contact ends 4 and 5, respectively. This is a substantially V-shaped oblique groove in which the angle of inclination changes to the angle and the angle change of the shoulder portion is larger than the angle change in the center portion and the mediate portion . The oblique grooves 2 and 3 are configured as oblique main grooves having a deep groove depth, and a large number of them are juxtaposed at intervals in the tire circumferential direction. R indicates the forward rotation direction of the tire. This tire is a radial tire having a directional pattern in which the normal rotation direction of the tire is determined when the tire is mounted.
[0017]
Reference numerals 6 and 7 denote circumferential grooves extending in the tire circumferential direction so as to intersect each of the oblique grooves 2 and 3 described above. The circumferential grooves 6 and 7 are disposed in the tire shoulder portion SH, and the groove depth is set to be shallower than the groove depths of the oblique grooves 2 and 3, and the groove depth of the oblique grooves 2 and 3 is 50. It is set to ~ 85%. The groove depth at the intersection of the circumferential grooves 6 and 7 and the oblique grooves 2 and 3 is configured as the groove depth of the oblique grooves 2 and 3. Further, the circumferential grooves 6 and 7 are set to have a groove width of 4 mm or more and within 15% of the ground contact width. The circumferential grooves 6 and 7 define shoulder blocks 8 and 9 between the oblique grooves 2 and 2 and the oblique grooves 3 and 3 adjacent to each other in the tire circumferential direction.
[0018]
As described above, the tire according to the present embodiment includes the oblique grooves 2 and 3 and the circumferential grooves 6 and 7 that intersect the oblique grooves 2 and 3 and extend in the tire circumferential direction. Compared to tires, the block configuration can be reduced by forming the circumferential grooves 6 and 7 and the oblique grooves 2 and 3 in terms of the pattern configuration, so that the shoulder blocks 8 and 9 are in contact with the road surface. The striking sound that is generated when doing this can be reduced.
[0019]
In the tire according to the present embodiment, since the groove depth of the circumferential grooves 6 and 7 is set to be shallower than the groove depth of the oblique grooves 2 and 3, the shoulder is likely to occur along the circumferential grooves 6 and 7. Buckling of the edge portions of the blocks 8 and 9 can be suppressed. In addition, the tire according to the present embodiment has an excessive decrease in block rigidity compared with a tire in which the groove depth of the circumferential grooves 6 and 7 is the same as or deeper than that of the oblique grooves 2 and 3. , 7 can be suppressed. Therefore, the tire of this embodiment can also ensure the handling stability with respect to the dry road surface.
[0020]
Particularly, in the tire according to this embodiment, the groove depth of the circumferential grooves 6 and 7 is 50 to 85% of the groove depth of the oblique grooves 2 and 3, and the groove width of the circumferential grooves 6 and 7 is set. The groove width is 4 mm or more and within 15% of the grounding width (distance between both grounding ends). As a result, a decrease in drainage performance on a wet road surface is suppressed, and an increase in block rigidity is prevented to prevent deterioration of tire noise, while buckling is suppressed to ensure steering stability on a dry road surface.
[0021]
Furthermore, in the tire of the present invention, the groove depth at the intersection of the circumferential grooves 6 and 7 and the oblique grooves 2 and 3 is the groove depth of the oblique grooves 2 and 3. Thereby, the drainage performance on the wet road surface is ensured by the oblique grooves 2 and 3 extending mainly from the vicinity of the tire equator EQ to the tire shoulder end SE through the ground contact ends 4 and 5, and in addition, the groove width is wide. The circumferential grooves 6 and 7 are also secured.
[0022]
Further, in the tire according to the present embodiment, the shoulder blocks 8 and 9 surrounded by the oblique grooves 2 and 3 and the circumferential grooves 6 and 7 are further divided into the lateral grooves 10 and 11 that divide the shoulder blocks 8 and 9. It is arranged with a deeper groove depth. Therefore, the shoulder blocks 8 and 9 further constitute small blocks 8a and 8b and small blocks 9a and 9b having the same block shape by the lateral grooves 10 and 11, respectively. Therefore, tire noise can be reduced and step wear can be suppressed by the small blocks 8a and 8b and the small blocks 9a and 9b.
[0023]
FIG. 2 is a schematic development view of a tread pattern showing another embodiment of the pneumatic radial tire according to the present invention. The tire of this embodiment is also a radial tire having a directional pattern in which the normal rotation direction of the tire is determined when the tire is mounted.
[0024]
As shown in the figure, the tire of this embodiment is shown in FIG. 1 except that circumferential grooves 12 and 13 extending in the tire circumferential direction are arranged on both sides near the tire equator EQ in the tire tread pattern shown in FIG. It is the structure provided with the same tread pattern as a tire. Therefore, in the tire of the present embodiment, the circumferential grooves 6 and 7 of the tire shoulder portion SH are shallower than the groove depths of the diagonal grooves 2 and 3 as in the tire of the embodiment shown in FIG. It is set, and is set to 50 to 85% of the groove depth of the oblique grooves 2 and 3. The groove depth at the intersection of the circumferential grooves 6 and 7 and the oblique grooves 2 and 3 is configured as the groove depth of the oblique grooves 2 and 3. Further, the circumferential grooves 6 and 7 are set to have a groove width of 4 mm or more and within 15% of the ground contact width. On the other hand, the circumferential grooves 12 and 13 arranged in the vicinity of the tire equator EQ are set so that the groove depth thereof is shallower than the groove depths of the oblique grooves 2 and 3, similarly to the circumferential grooves 6 and 7 of the tire shoulder portion SH. However, it can be set deeply, and the depth is not limited in the present invention. In the tire according to this embodiment, a total of four circumferential grooves intersecting with the oblique grooves 2 and 3 configured as oblique main grooves are arranged.
[0025]
Since the tire according to the present embodiment is as described above, the mediate block 14 defined by the oblique grooves 2, 2 and the two circumferential grooves 6, 12 at both mediate portions of the tire tread surface, and the oblique The mediate block 15 defined by the grooves 3 and 3 and the two circumferential grooves 7 and 13 is arranged. In addition, the other code | symbol in FIG. 2 has shown the site | part of the same code | symbol of FIG. 1 as it is.
[0026]
Accordingly, the tire according to the present embodiment can also improve drainage performance on a wet road surface and steering stability on a dry road surface while reducing tire noise as in the tire of FIG.
[0027]
FIG. 3 is a schematic development view of a tread pattern showing another embodiment of the pneumatic radial tire according to the present invention. The tire of this embodiment is also a radial tire having a directional pattern in which the normal rotation direction of the tire is determined when the tire is mounted.
[0028]
In the tire of this embodiment, as shown in the figure, one circumferential groove 16 extending in the tire circumferential direction is formed in the vicinity of the tire equator EQ, and an oblique groove 17 configured as a substantially V-shaped oblique main groove is formed. While continuing from the vicinity of the tire equator EQ, the inclination angle changes from the small inclination angle to the large inclination angle with respect to the tire anti-rotation direction toward the ground contact ends 4 and 5 respectively , and the shoulder angle changes at the center portion and the mediate portion. A pattern configuration similar to that of the tire shown in FIG. 1 is adopted except that the configuration is larger than the angle change . Therefore, also in the tire of this embodiment, the circumferential grooves 6 and 7 of the tire shoulder portion SH are set so that the groove depth is shallower than the groove depth of each oblique groove 17 as in the tire of the embodiment shown in FIG. And 50 to 85% of the depth of the oblique groove 17 is set. The groove depth at the intersection of the circumferential grooves 6 and 7 and the oblique groove 17 is configured as the groove depth of the oblique groove 17. Further, the circumferential grooves 6 and 7 are set to have a groove width of 4 mm or more and within 15% of the ground contact width. On the other hand, the circumferential groove 16 disposed in the vicinity of the tire equator EQ is also set to have a groove depth shallower than that of the oblique groove 17, similar to the circumferential grooves 6 and 7 of the tire shoulder portion SH. However, the depth is not limited in the present invention.
[0029]
Therefore, in the tire according to the present embodiment, the center block 18 defined by the oblique grooves 17 and 17 and the two circumferential grooves 6 and 16 is formed in the tire center portions located on both sides of the tire tread surface with the tire equator EQ interposed therebetween. And the center block 19 defined by the oblique grooves 17 and 17 and the two circumferential grooves 7 and 16 are arranged. In addition, the other code | symbol in FIG. 3 has shown the site | part of the same code | symbol of FIG. 1 as it is.
[0030]
Accordingly, the tire according to the present embodiment can also improve drainage performance on a wet road surface and steering stability on a dry road surface while reducing tire noise as in the tire of FIG.
[0031]
FIG. 4 is a schematic development view of a tread pattern showing still another embodiment of the pneumatic radial tire according to the present invention. The tire of this embodiment is a tire provided with the symmetrical pattern which does not have a specific rotation direction like illustration. The tire according to the present embodiment has an inclination angle from a small inclination angle to a large inclination angle with respect to the rotation direction, one of the tires in the counter-rotating direction and the other from the vicinity of the tire equator EQ to the ground contact ends 4 and 5 respectively. There is a substantially S-shaped slanted groove 2, 20 that changes and the angle change of the shoulder portion is larger than the angle change in the center portion and the mediate portion.
[0032]
That is, as shown in the figure, the right region across the tire equator EQ has the same pattern as in FIG. The reference numerals in this region are the same as those shown in FIG. On the other hand, the region on the left side of the tire equator EQ has a pattern opposite to that in FIG. In the tire according to the present embodiment, in the left region across the tire equator EQ, the oblique groove 20 has an oblique groove 20 whose inclination angle gradually changes from a small inclination angle to a large inclination angle with respect to the tire rotation direction. is doing. The circumferential groove 7 is set to have a groove depth shallower than that of the oblique groove 20, and intersects the oblique groove 20 at the groove depth of the oblique groove 20. The circumferential groove 7 defines a shoulder block 21 between the oblique grooves 20 adjacent to each other in the tire circumferential direction.
[0033]
Accordingly, the tire according to the present embodiment can also improve drainage performance on a wet road surface and steering stability on a dry road surface while reducing tire noise as in the tire of FIG.
[0034]
FIG. 5 is a schematic development view of an asymmetric tread pattern showing another embodiment of the pneumatic radial tire according to the present invention. In the tire of the present embodiment, oblique grooves 22 extending from the vicinity of the tire equator to the tire shoulder end SE through the respective ground contact ends 4 and 5 are continuously formed in a substantially S shape. In this tire, a circumferential groove 23 having a groove depth shallower than that of the oblique groove 22 is provided only on one side of the tire shoulder portion SH across the tire equator. The circumferential groove 23 intersects the oblique groove 22 at the groove depth of the oblique groove 22. A lateral groove 24 extending from the ground contact end 5 to the circumferential groove 2 is formed in a region between the oblique grooves 22 in the tire circumferential direction. The lateral groove 24 divides the shoulder block 25 formed between the oblique groove 22 and the oblique groove 22, and the shoulder block 25 is composed of a small block 25a and a small block 25b.
[0035]
Therefore, in the case of this tire, it is possible to improve the drainage performance on the wet road surface and the steering stability on the dry road surface while reducing the tire noise in the tire shoulder portion SH on one side of the tire tread surface.
[0036]
By the way, as for the tire of the said embodiment, the groove depth of all the circumferential grooves is set shallower than the groove depth of the said diagonal groove | channel, and the said diagonal groove | channel cross | intersects in the groove depth of the said diagonal groove | channel. Yes. However, in the present invention, as long as the tire shoulder portion on at least one side of the tire tread surface has the circumferential groove, a tire having a circumferential groove other than the circumferential groove, an oblique groove other than the oblique groove, and other grooves is also included. It is what
[0037]
Moreover, in the tire of the said embodiment, although all the lateral grooves in a tire shoulder part are arrange | positioned in order to divide the shoulder block located between the diagonal groove | channel and the diagonal groove | channel in a tire circumferential direction, it is limited to this. Not. For example, in order to divide into two or more, two or more lateral grooves can be arranged. Further, in the tires of the above-described embodiments, the arrangement direction and the groove depth of the lateral grooves are all matched with the shoulder region portion of the oblique grooves described above, but the present invention is not limited to this. For example, the groove depth can be formed shallower or deeper than the shoulder region portion of the oblique groove while the lateral groove arrangement direction is extended to the mediate region portion.
[0038]
【Example】
1 has a tread pattern of FIG. 1 with a ground contact width of 173 mm, and tires of the tire size 215 / 45ZR17 of the example and the comparative example are manufactured under the conditions shown in Table 1, and a pattern noise test, a hydroplaning test, and a dry road Each performance evaluation test of the steering stability test was conducted. The ground contact width is a measured value based on the “G” chapter of the JATMA YEAR BOOK 1998 edition.
[0039]
In the pattern noise test, each tire of the example and the comparative example was incorporated in a rim of 17 × 7-JJ, and the in-vehicle sound was measured based on the test method of JASO-C606 under the conditions of an air pressure of 220 KPa and a load of 400 kg. Example 1 The measured value of a tire was expressed as an index, and the evaluation was made with the reciprocal value. The larger the value, the better the tire noise reduction effect.
[0040]
In the hydroplaning test, the tires of the example and comparative example were similarly mounted on a 17 × 7-JJ rim and mounted on an actual vehicle with an air pressure of 220 KPa, on a wet road surface with a water depth of 8 mm under the load condition of one passenger. The speed when hydroplaning occurred was measured, and the measured value of the tire of Comparative Example 1 was set to 100 and evaluated as an index. The larger the value, the better the wet road drainage performance.
[0041]
In the dry road handling stability test, the tires of the examples and comparative examples were similarly incorporated into a rim of 17 × 7-JJ, mounted on an actual vehicle with an air pressure of 220 KPa, and various kinds of dry road surfaces under the load conditions of one passenger. A feeling test in a running mode was performed, an average value thereof was calculated, and the measured value of Comparative Example 1 tire was displayed as an index and evaluated. The larger the value, the better the dry road steering stability performance. Examples of the various traveling modes include high-speed straight traveling, lane change and slalom traveling, and cornering traveling with large and small turning radii.
[0042]
Table 1 shows the results of these tests. In the table, the groove depth D of the circumferential groove, the groove width W of the circumferential groove, and the groove depth d of the oblique groove are as shown in FIG. FIG. 6 is a schematic cross-sectional view of the tire in FIG. As in FIG. 1, 1 is a tire tread portion, 2, 3 are oblique grooves, 4 and 5 are grounding ends, 6 and 7 are circumferential grooves, and 8 and 9 are shoulder blocks. In Table 1, D / d indicates the ratio of the groove depth D of the circumferential groove to the groove depth d of the oblique groove. Further, the contact width ratio of the circumferential groove indicates the groove width ratio (%) with respect to the contact width.
[0043]
[Table 1]

[0044]
From Table 1, compared with the tire of the comparative example 1 with the same groove depth of the circumferential direction groove | channel and the diagonal groove | channel, all the Example tires have wet road drainage performance and dry road handling stability performance, suppressing the deterioration of tire noise. It shows that it is good. In particular, in the case of a tire (D / d is 0.5 to 0.85) in which the groove depth D of the circumferential groove is 50% to 85% of the groove depth d of the oblique groove, it is compared with the tire of Comparative Example 1. The wet road drainage performance and dry road handling stability performance are improved while reducing tire noise.
[0045]
Further, in the case of the comparative example 4 tire in which the groove width of the circumferential groove is less than 4 mm, the block rigidity is increased, the tire noise and the drainage are deteriorated, and the contact width ratio exceeds 15% in the comparative example 5 tire. In this case, buckling tends to occur along the circumferential groove, and the steering stability on the dry road surface is lowered.
[0046]
【The invention's effect】
As described above, the pneumatic radial tire of the present invention has air on the tire tread surface having an oblique groove extending from the vicinity of the tire equator to the tire shoulder end and a circumferential groove extending across the oblique groove and extending in the tire circumferential direction. In entering radial tires,
The circumferential groove has a groove width of 4 mm or more and within 15% of the ground contact width,
The groove depth of the circumferential groove is set to be less than the groove depth of the oblique groove and 50 to 85% of the groove depth of the oblique groove,
The groove depth at the intersection of the circumferential groove and the oblique groove is the groove depth of the oblique groove,
The oblique groove has a structure in which the inclination angle changes from a small inclination angle to a large inclination angle from the vicinity of the tire equator to both contact ends, and the angle change of the shoulder portion is larger than the angle change in the center portion and the mediate portion ,
Since the circumferential groove is a pneumatic radial tire arranged at least on one shoulder, it is possible to simultaneously improve drainage on wet road surfaces and steering stability on dry road surfaces while reducing tire noise. it can.
[Brief description of the drawings]
FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic radial tire according to the present invention.
FIG. 2 is a schematic development view of a tread pattern showing the other embodiment.
FIG. 3 is a schematic development view of a tread pattern showing the other embodiment.
FIG. 4 is a schematic development view of a tread pattern showing another embodiment having no tire rotation direction.
FIG. 5 is a schematic development view of a tread pattern showing another embodiment configured with an asymmetric pattern.
FIG. 6 is a schematic cross-sectional view of the tire in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tire tread part 2 Diagonal groove 3 Diagonal groove 4 Ground end 5 Ground end 6 Circumferential groove 7 Circumferential groove 8 Shoulder block 9 Shoulder block 10 Lateral groove 11 Lateral groove 12 Circumferential groove 13 Circumferential groove 14 Mediate block 15 Mediate block 16 circumferential groove 17 oblique groove 18 center block 19 center block 20 oblique groove 21 shoulder block 22 oblique groove 23 circumferential groove 24 lateral groove 25 shoulder block SH tire shoulder SE tire shoulder end

Claims (2)

In a pneumatic radial tire having an oblique groove extending from the tire equator to the tire shoulder end on the tire tread surface, and a circumferential groove extending in the tire circumferential direction intersecting the oblique groove,
The circumferential groove has a groove width of 4 mm or more and within 15% of the ground contact width,
The groove depth of the circumferential groove is set to be less than the groove depth of the oblique groove and 50 to 85% of the groove depth of the oblique groove,
The groove depth at the intersection of the circumferential groove and the oblique groove is the groove depth of the oblique groove,
The oblique groove has a structure in which the inclination angle changes from a small inclination angle to a large inclination angle from the vicinity of the tire equator to both contact ends, and the angle change of the shoulder portion is larger than the angle change in the center portion and the mediate portion ,
A pneumatic radial tire characterized in that the circumferential groove is disposed at least on one side of the tire shoulder. The pneumatic radial tire according to claim 1, wherein a lateral groove that divides the shoulder block is disposed in a shoulder block surrounded by the oblique groove and the circumferential groove.

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