JP2004098938A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire having excellent draining performance and hardly causing uneven wear, particularly, a pneumatic radial tire for small truck mainly commercially used on a good road. <P>SOLUTION: In this pneumatic tire, at least three main grooves 2a-2c continuously extended in the tire circumferential direction C are arranged in a tread part 1 to form a plurality of lines of ribs 3a-3d. The tire equatorial-side land parts 5a and 5c of the ribs 3b and 3c are formed of a number of pseudo blocks 6a and 6b partitioned by a number of lateral grooves 7a and 7b extended from the main grooves 2a facing thereto in the direction crossing the direction C, circumferential thin grooves 9a and 9b consisting of first thin groove parts 8a and 8c and second thin groove parts 8b and 8d intermittently arranged in zigzag on two tire circumferences within the ribs 3b and 3c, and lateral sipings 10a-10d arranged between the grooves 7a and 7b and the grooves 9a and 9b when the grooves 7a and 7b don't communicate with the grooves 9a and 9b and between the groove parts 8a and 8c and the groove parts 8b and 8d, and extended in the direction crossing to the direction C. Further, the rigidity of the tire equatorial-side land part 5a and 5c is smaller than that of the tread end-side land parts 5b and 5d. <P>COPYRIGHT: (C)2004,JPO

Description

【００４８】
（性能評価）
（１）排水性能評価試験
排水性能は、上記各供試タイヤをリム（サイズ：５．５Ｊ）に組み付けてタイヤ車輪とし、このタイヤ車輪を２トントラックに装着し、かかるトラックで濡れた路面（鉄板路）を時速４０ｋｍで走行させ、その後、急ブレーキをかけたときの制動距離を測定し、この測定値から評価した。
【００４９】
（２）偏摩耗評価試験
偏摩耗は、上記各供試タイヤをリム（サイズ：５．５Ｊ）に組み付けてタイヤ車輪とし、このタイヤ車輪を２トントラックに装着し、かかるトラックで良路（高速道路５０％＋一般道路５０％）を２万ｋｍ走行させた後、タイヤ赤道側に位置するリブのトレッド端側陸部部分でヒールアンドトゥ摩耗により生じた段差量を測定し、この測定値から偏摩耗の発生度合いを評価した。
【００５０】
表２にその評価結果を示す。表２中の排水性能及び偏摩耗の数値はいずれも、従来例２を１００とした指数比で示してあり、小さいほど排水性能が優れ、偏摩耗の発生が抑制されている。
【００５１】
【表２】

【００５２】
表２に示す評価結果から、実施例１〜５はいずれも、従来例１および従来例２に比べて、排水性能と偏摩耗特性の総合バランス性能に優れている。
【００５３】
【発明の効果】
この発明は、リブのタイヤ赤道側陸部分を多数個の擬似ブロックで構成することによって、偏摩耗を抑制しつつ排水性能の向上を図った空気入りタイヤ、特に商用で良路主体で使用される小型トラック用空気入りラジアルタイヤの提供が可能になった。
【図面の簡単な説明】
【図１】この発明に従う空気入りタイヤのトレッド部の一部の展開図である。
【図２】この発明に従う他の空気入りタイヤのトレッド部の一部の展開図である。
【図３】横溝の実施態様を示す斜視図である。
【図４】横溝の他の実施態様を示す斜視図である。
【図５】横溝の他の実施態様を示す斜視図である。
【図６】横溝の他の実施態様を示す斜視図である。
【図７】従来タイヤ（従来例１）のトレッド部の一部の展開図である。
【符号の説明】
１　トレッド部
２，　２ａ〜２ｃ　主溝
３ａ〜３ｄ　リブ
４ａ，　４ｂ　トレッド端
５ａ，　５ｃ　リブのタイヤ赤道側陸部部分
５ｂ，　５ｄ　リブのトレッド端側陸部部分
６ａ，　６ｂ　擬似ブロック
７ａ，　７ｂ　横溝
８ａ，　８ｃ　第１細溝部
８ｂ，　８ｄ　第２細溝部
９ａ，　９ｂ　周方向細溝
１０ａ〜１０ｄ　横サイプ
１１　タイヤ赤道側
１２　トレッド端側
１３　横溝の溝壁
１４　タイヤ径方向
１５　一端開口サイプ
１６　切欠き部
１７　周方向補助サイプ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire for improving drainage performance while suppressing uneven wear, and more particularly to a pneumatic radial tire for a light truck which is mainly used on a commercial road.
[0002]
[Prior art]
Pneumatic tires, especially tires mounted on vehicles such as the above-mentioned light trucks, have excellent drainage due to an increased edge component when a block pattern is employed as a tread pattern, but have a heel-and-toe structure. The problem of uneven wear such as wear occurs.
[0003]
For this reason, in such a tire, in order to eliminate the above-mentioned problem, it is general to adopt a pure rib-based pattern as a tread pattern.
[0004]
However, when a pure rib-based pattern is employed, sufficient drainage performance cannot be obtained because of insufficient edge components.
[0005]
Therefore, it has been difficult for a tire having a conventional tread pattern to both suppress uneven wear and improve drainage.
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire, in which the tire equatorial land portion of a rib is constituted by a large number of pseudo blocks, thereby improving drainage performance while suppressing uneven wear, particularly for use mainly on a commercial road. To provide a pneumatic radial tire for light trucks.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a pneumatic tire in which at least three main grooves continuously extending in a tire circumferential direction are arranged in a tread portion to form a plurality of rows of ribs. When at least one row of the ribs is further subdivided into two rows in the tire circumferential direction, a tire equatorial side land portion and a tread end side land portion, the tire equatorial side land portion faces it. It is composed of a number of lateral grooves extending from the main groove in a direction intersecting the tire circumferential direction, and a first narrow groove portion and a second narrow groove portion intermittently arranged in a staggered manner on two tire circumferences in the rib. A circumferential narrow groove, disposed between the lateral groove and the circumferential narrow groove when the transverse groove and the circumferential narrow groove are not in communication with each other, and between the first narrow groove portion and the second narrow groove portion, and arranged in the tire circumferential direction. A large number of compartments separated by transverse sipes It consists of similar blocks, and the rigidity of the tire equator-side land zone is a pneumatic tire characterized by less than the rigidity of the tread end side land zone.
[0008]
Further, the lateral groove preferably extends at an angle of 50 to 90 ° with respect to the tire circumferential direction.
[0009]
Further, the lateral groove is a dead end groove having a terminal end in the rib, or the lateral groove is an open-ended groove communicating with both main grooves and the rigidity of the land portion of the rib due to the provision of the lateral groove has a tire equator side. It is preferable that the land portion is smaller than the land portion on the tread end side.
[0010]
When the lateral groove is a dead end groove, the end position of the lateral groove is within a range of 30 to 50% of the rib width from the main groove to be opened, and the groove width of the lateral groove is equal to the groove width of the main groove. More preferably, it is in the range of 20 to 40% and / or the groove depth of the lateral groove is in the range of 20 to 100% of the groove depth of the main groove.
[0011]
When the lateral groove is an open groove at both ends, the groove depth of the lateral groove is preferably shallower from the tire equator side of the rib toward the tread end, and, in addition, the groove depth of the lateral groove is the main groove. More preferably, the groove depth is in the range of 25 to 100% on the tire equator side and 10 to 30% on the tread end side. It is preferable that the width of the lateral groove is 20 to 40% of the width of the main groove on the tire equator side and 10 to 20% on the tread end side with respect to the width of the main groove. %, And the angle of the groove wall with respect to the tire radial direction is preferably increased from the tire equator side to the tread end side of the rib. Is the angle of the groove wall to the tire radial direction In the range of 0 to 20 ° in ya equator side, it is more preferably in the range of 10 to 25 ° at the tread end side.
[0012]
Further, the separation distance between the first narrow groove portion and the second narrow groove portion of the circumferential narrow groove measured along the tire circumferential direction is preferably in the range of 15 to 50% of the arrangement interval of the lateral groove. The circumferential length of each of the first narrow groove portion and the second narrow groove portion in the direction narrow groove is in the range of 10 to 45% of the interval between the horizontal grooves, and the width of the circumferential narrow groove is the groove of the main groove. It is more preferable that the width is in the range of 5 to 25% of the width and / or the groove depth of the circumferential narrow groove is in the range of 20 to 50% of the groove depth of the main groove.
[0013]
Further, it is preferable that the cut depth of the horizontal sipe is substantially the same as the groove depth of the main groove.
[0014]
Further, it is preferable to provide notches at the ends of the ribs at equal intervals on the tire circumference. In addition, the notch has a tire width direction dimension of 5 to 15% of the rib width. And the tire circumferential dimension is in the range of 10 to 30% with respect to the interval between the lateral grooves, and / or the depth dimension is 80% with respect to the groove depth of the main groove. More preferably, it is in the range of 100%.
[0015]
Furthermore, it is preferable to provide a one-end opening sipe extending from the main groove in the tire width direction at the end of the rib, and the one-end opening sipe has a cut length and a circumferential arrangement interval both smaller than the groove width of the main groove. It is more preferred that there be.
Note that a narrow circumferential auxiliary sipe extending in the tire circumferential direction may be provided in a rib defined by the tread end and the circumferential groove.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a part of a tread pattern of a pneumatic tire according to the present invention.
[0017]
In the pneumatic tire having the tread portion 1 shown in FIG. 1, at least three main grooves 2 extending continuously in the tire circumferential direction C are arranged in the tread portion 1 to form a plurality of rows of ribs 3. In FIG. 1, the main groove 2 includes one central main groove 2a located on the tire equator, and a pair of side main grooves 2b located between the central main groove 2a and the tread ends 4a, 4b. , 2c, and the tread portion 1 is defined by four rows of ribs 3a, 3b, 3c, 3d.
[0018]
In the present invention, since the configuration of the tread portion 1 is characteristic, the tire structure other than the tread portion 1 does not need to be modified, and therefore the description is omitted.
[0019]
The main feature of the configuration of the present invention is that at least one row of the ribs 3a to 3d (two rows of ribs 3b and 3c in the case of FIG. 1) is mounted on the tire equatorial side land in the tire circumferential direction C. When the tire portions 5a and 5c and the tread end side land portions 5b and 5d are further divided into two rows, the tire equatorial side land portions 5a and 5c are divided into a number of pseudo blocks 6a and 6b having appropriate shapes. And the rigidity of the tire equator side land portions 5a, 5c is made smaller than the rigidity of the tread end side land portions 5b, 5d. More specifically, the tire equatorial side land portions 5a, 5d are 5c has a large number of lateral grooves 7a, 7b extending from the main groove 2a facing the main groove 2a in a direction intersecting the tire circumferential direction C, and intermittently intermittently on two tire circumferences in the ribs 3b, 3c. The first narrow groove portions 8a, 8c provided and The circumferential narrow grooves 9a, 9b composed of the second narrow grooves 8b, 8d, and the transverse grooves 7a, 7b and the circumferential narrow grooves 9a, 9b when the transverse grooves 7a, 7b and the circumferential narrow grooves 9a, 9b do not communicate with each other. And between the first narrow grooves 8a, 8c and the second narrow grooves 8b, 8d, and are defined by horizontal sipes 10a, 10b, 10c, 10d extending in a direction intersecting the tire circumferential direction C. And the rigidity of the tire equator side land portions 5a and 5c is made smaller than the rigidity of the tread end side land portions 5b and 5d. By adopting it, it is possible to improve drainage performance while suppressing uneven wear.
[0020]
Hereinafter, the process of completing the present invention will be described together with the operation.
In general, if the tire has a rib pattern, heel and toe wear does not occur, but sufficient drainage performance is not obtained.On the other hand, by arranging a lateral groove communicating with the two main grooves dividing the tread portion into ribs, If the tire has a block pattern in which ribs are divided into a large number of blocks, good drainage is obtained, but heel-and-toe wear is likely to occur.
[0021]
For this reason, the inventor has studied to develop a new tread pattern excellent in drainage performance while suppressing uneven wear such as heel-and-toe wear, taking into account the advantages of the rib pattern and the block pattern.
[0022]
As a result, the land portion of the tire block having the block pattern located on the tread end side, that is, the main groove located on the tread end side (in FIG. 1, the side main groove 2b) , 2c), it is found that heel and toe wear is apt to occur in the portion of the lateral groove adjacent to the vehicle, particularly when it is attached to the front wheel of the vehicle. Strictly speaking, by terminating the rib at the tire equatorial side land portion, and forming a dead end groove (see FIG. 3) that does not open to the side main groove, the rib tread end side land portion is formed as a rib. It has been found that the occurrence of heel-and-toe wear can be suppressed. In addition, a horizontal sipe may be provided instead of the horizontal groove provided on the tire equator side land portion of the rib, but such a case is not preferable because drainage performance and edge rigidity are inferior.
[0023]
It was also found that the circumferential narrow grooves 9a and 9b that divide the ribs into the tire equator side land portions should preferably be narrow grooves instead of sipes in consideration of drainage performance and edge rigidity. In the present invention, the case where the groove width is 2 to 5 mm is distinguished as "small groove", and the case where the cut width is less than 2 mm is distinguished as "sipe".
[0024]
Furthermore, the circumferential narrow grooves 9a and 9b are arranged in a straight shape in the tire circumferential direction in order to increase the edge component in the tire width direction and effectively improve drainage performance, particularly braking performance on a wet road surface. However, it was also found that the first and second fine grooves 8a and 8c and the second and fine grooves 8b and 8d, which are intermittently arranged in a zigzag pattern on the two tire circumferences in the ribs, were also good.
[0025]
In addition, when the lateral groove and the circumferential narrow groove are not in communication with each other, they extend in a direction intersecting the tire circumferential direction between the lateral groove and the circumferential narrow groove, and between the first narrow groove and the second narrow groove. It has also been found that if the transverse sipes 10a, 10b, 10c, 10d are provided, it is possible to further increase the tire width direction component while suppressing heel and toe wear.
[0026]
In this manner, the tire equator-side portions 5a, 5c of the ribs 3b, 3c are substantially formed by the main groove 2a, the lateral groove 7a or 7b, the circumferential narrow groove 9a or 9b, and the lateral sipes 10a, 10b or 10c, 10d. By configuring a large number of pseudo blocks 6a or 6b sectioned into, and by setting the rigidity of the tire equator side land portion 5a or 5c smaller than the rigidity of the tread end side land portion 5b or 5d, They succeeded in improving drainage while suppressing heel and toe wear, and completed the present invention.
[0027]
Further, it is preferable that the lateral grooves 7a and 7b extend at an angle of 50 to 90 ° with respect to the tire circumferential direction C. If the angle is less than 50 °, the edge component in the tire width direction may be insufficient, and it may not be possible to effectively improve braking performance particularly on a wet road surface.
[0028]
When the lateral grooves 7a and 7b are dead ends, it is preferable that the end positions of the lateral grooves 7a and 7b are within a range of 30 to 50% of the rib width W1 from the main groove 2a to be opened. If it is less than 30%, the edge component in the tire width direction tends to be insufficient, and if it exceeds 50%, heel and toe wear may not be sufficiently suppressed.
[0029]
Further, the groove width w2 of the lateral grooves 7a and 7b is preferably in the range of 20 to 40% of the groove width w1 of the main groove 2a. If it is less than 20%, sufficient drainage tends not to be obtained, and if it exceeds 40%, the rigidity of the land portion on the equatorial side of the tire becomes low, and heel and toe wear is likely to occur.
[0030]
Further, the groove depth d2 of the lateral grooves 7a and 7b is preferably in the range of 20 to 100% of the groove depth d1 of the main groove 2a. If it is less than 20%, sufficient drainage may not be obtained.
[0031]
The case where the lateral grooves 7a and 7b are dead-end grooves has been described so far. However, as another embodiment, as shown in FIG. In addition, the land rigidity of the ribs 3b, 3c due to the arrangement of the lateral grooves 7a, 7b may be configured to be smaller in the tire equator side land portions 5a, 5c than in the tread end side land portions 5b, 5d. .
[0032]
Specifically, for example, as shown in FIG. 4, the groove depth d2 of each of the lateral grooves 7a and 7b is configured so as to be shallower from the tire equator side 11 to the tread end side 12 of the rib, or as shown in FIG. As shown, the groove width w2 of the lateral grooves 7a, 7b is configured so as to become narrower from the tire equator side 11 of the ribs 3b, 3c toward the tread end side 12, or, as shown in FIG. , 7b so that the angle θ of the groove wall 13 with respect to the tire radial direction 14 increases from the tire equator side 11 of the ribs 3b, 3c toward the tread end side 12. 3 to 6 are conceptually shown so that the shapes of the lateral grooves 7a and 7b can be easily understood.
[0033]
When changing the groove depth d2 of the lateral grooves 7a and 7b, the groove depth d2 of the lateral grooves 7a and 7b is set to 25 to 100% on the tire equator side 11 with respect to the groove depth d1 of the main groove 2a. , The range of 10 to 30% on the tread end side 12 is more preferable. If it is less than 25% on the tire equator side 11, sufficient drainage may not be obtained. On the other hand, if it is less than 10% on the tread end side 12, sufficient drainage may not be obtained. If it exceeds 30%, there is a tendency that heel and toe wear cannot be suppressed.
[0034]
When the groove width w2 of the lateral grooves 7a, 7b is changed, the groove width w2 of the lateral grooves 7a, 7b is set in the range of 20 to 40% on the tire equator side 11 with respect to the groove width w1 of the main groove 2a. It is more preferable to set the range of 10 to 20% on the tread end side 12. If it is less than 20% on the tire equator side 11, sufficient drainage may not be obtained. If it exceeds 40%, heel-and-toe wear tends to occur. If it is less than 10%, sufficient drainage tends not to be obtained, and if it exceeds 20%, heel and toe wear is likely to occur.
[0035]
Further, when changing the groove wall angle θ of the lateral grooves 7a and 7b, the angle θ of the groove wall 13 with respect to the tire radial direction 14 is in the range of 0 to 20 ° on the tire equator side 11 when changing the groove wall angle θ of the lateral grooves 7a and 7b. It is more preferable that the angle is in the range of 10 to 25 ° on the tread end side 12. If the tire is more than 20 ° on the equator side 11, sufficient drainage may not be obtained due to abrasion of the tread rubber after the middle period of use of the tire. This is because when the angle exceeds 25 °, a groove bottom having a large curvature cannot be formed, and problems such as cracks are likely to occur.
[0036]
In addition, the separation distance L1 measured along the tire circumferential direction C between the first narrow groove portions 8a, 8c and the second narrow groove portions 8b, 8d of the circumferential narrow grooves 9a, 9b is 15 times the horizontal groove arrangement distance D. It is preferably in the range of 50% to 50%. If it is less than 15%, the tire width direction edge component exhibiting traction drainage tends to be insufficient, and if it exceeds 50%, the tire circumferential edge component exhibiting lateral drainage tends to be insufficient. Because there is.
[0037]
The circumferential length a1 of the first narrow groove portions 8a, 8c of the circumferential narrow grooves 9a, 9b and the circumferential length a2 of the second narrow groove portions 8b, 8d are both 10 to 45 of the spacing D of the transverse grooves 7a, 7b. % Is preferable. If it is less than 10%, there is a tendency that the tire circumferential edge component exhibiting lateral drainage tends to be insufficient, and if it exceeds 45%, the tire width direction edge component exhibiting traction drainage is insufficient. This is because they tend to do so.
[0038]
The groove width w3 of the circumferential narrow grooves 9a, 9b is preferably in the range of 5 to 25% of the groove width w1 of the main groove 2a. If it is less than 5%, the negative rate may be insufficient and sufficient drainage may not be obtained, and if it is more than 15%, the rigidity of the entire rib is reduced, and the wear resistance and steering stability are adversely affected. This is because there is a tendency to exert
[0039]
The groove depth d3 of the circumferential narrow grooves 9a, 9b is preferably in the range of 20 to 50% of the groove depth d1 of the main groove 2a. If it is less than 20%, there is a risk that it will be worn out immediately and it will not be possible to obtain sufficient drainage properties after the middle stage of wear, and if it is more than 50%, the rigidity of the entire rib may be reduced. .
[0040]
Further, it is preferable that the cut depth d4 of the lateral sipes 10a to 10d is substantially the same as the groove depth d1 of the main groove 2a from the viewpoint of securing edge components until the end of wear.
[0041]
Furthermore, in order to reduce the forced abrasion of the end of the rib 3 due to the lateral input, it is preferable to provide the one end opening sipe 15 extending from the main groove 2 in the tire width direction at the end of the rib 3.
More preferably, the one-end opening sipe 15 has a cut length x1 and a circumferential arrangement interval y1 both smaller than or equal to a groove width w1 of the main groove 2.
[0042]
Furthermore, in the case where the one-end opening sipe 15 is provided at the end of the rib 3, at the land portion where the sipe 15 is arranged, it is possible to prevent the riverware generated from heel and toe wear or the like from being connected in the circumferential direction. From the viewpoint of increasing the edge component in the tire width direction, it is preferable to provide notches 16 at the ends of the ribs 3 at equal intervals on the tire circumference.
The notch 16 has a width in the tire width range of 5 to 15% with respect to the width of the rib, and a circumferential dimension m5 of the notch 16 is 10 to 10 with respect to the interval D between the lateral grooves 7a and 7b. A point of 30% and a dimension d5 in the depth direction of 80 to 100% with respect to the groove depth d1 of the main groove 2 optimize the rigidity of the rib and suppress uneven wear. Is more preferable.
The shape of the notch 16 is preferably a semi-elliptical shape or a semi-circular shape, in addition to the trapezoidal shape shown in FIG.
[0043]
In order to suppress the one-sided wear of the shoulder ribs, a narrow width extending in the tire circumferential direction, preferably 1 mm or less, is provided in the ribs 3a, 3d defined by the tread ends 4a, 4b and the circumferential grooves 2b, 2c. May be provided.
[0044]
What has been described above is merely an example of the embodiment of the present invention, and various changes can be made within the scope of the claims. FIG. 1 shows a case where the pseudo blocks 6a and 6b are formed in the tire equatorial side land portions 5a and 5c of the two rows of ribs 3b and 3c located on the tire equatorial side among the ribs 3a to 3d. A pseudo block may be formed at the tire equatorial side land portion of the ribs 3a and 3d.
[0045]
【Example】
Next, a pneumatic tire according to the present invention was prototyped and its performance was evaluated, and will be described below.
The tire of Example 1 has the tread pattern shown in FIG. 1, and the tires of Examples 2 to 5 (however, Example 3 has a shape in which the lateral groove changes) have the tread pattern shown in FIG. The tire size is 195 / 85R16 and has the specifications shown in Table 1. The tire structure other than the tread pattern was the same as a normal pneumatic radial tire for a small truck.
[0046]
For comparison, a tire having a rib pattern shown in FIG. 7 (conventional example 1) and a lateral groove having a tread pattern shown in FIG. 2 but having constant dimensions (groove width, groove depth, groove wall angle, etc.) are shown. The tire having the conventional block pattern (conventional example 2) was also prototyped.
[0047]
[Table 1]

[0048]
(Performance evaluation)
(1) Drainage performance evaluation test The drainage performance was determined by assembling each of the test tires described above on a rim (size: 5.5 J) to form a tire wheel, mounting the tire wheel on a 2-ton truck, and using a wet road surface (iron plate) Road) at a speed of 40 km / h, and then the braking distance when a sudden brake was applied was measured and evaluated from the measured values.
[0049]
(2) Uneven wear evaluation test Uneven wear is evaluated by assembling each of the test tires described above on a rim (size: 5.5 J) to form tire wheels, mounting the tire wheels on a 2-ton truck, and using such a truck on a good road (expressway). (50% + 50% of a general road)) after traveling 20,000 km, measure the amount of step caused by heel and toe wear at the land portion on the tread end side of the rib located on the tire equator side. The degree of occurrence was evaluated.
[0050]
Table 2 shows the evaluation results. The drainage performance and uneven wear values in Table 2 are all shown as index ratios with Conventional Example 2 being 100. The smaller the value, the better the drainage performance and the more uneven wear is suppressed.
[0051]
[Table 2]

[0052]
From the evaluation results shown in Table 2, all of Examples 1 to 5 are superior to Conventional Example 1 and Conventional Example 2 in the overall balance performance of drainage performance and uneven wear characteristics.
[0053]
【The invention's effect】
The present invention is a pneumatic tire that improves drainage performance while suppressing uneven wear by forming the tire equatorial side land portion of the rib with a large number of pseudo blocks, and is particularly used mainly on a good road in commercial use. It is now possible to provide pneumatic radial tires for light trucks.
[Brief description of the drawings]
FIG. 1 is a developed view of a part of a tread portion of a pneumatic tire according to the present invention.
FIG. 2 is a developed view of a part of a tread portion of another pneumatic tire according to the present invention.
FIG. 3 is a perspective view showing an embodiment of a lateral groove.
FIG. 4 is a perspective view showing another embodiment of the lateral groove.
FIG. 5 is a perspective view showing another embodiment of the lateral groove.
FIG. 6 is a perspective view showing another embodiment of the lateral groove.
FIG. 7 is a development view of a part of a tread portion of a conventional tire (conventional example 1).
[Explanation of symbols]
1 Tread portion 2, 2a-2c Main grooves 3a-3d Ribs 4a, 4b Tread ends 5a, 5c Tire equator side land portions 5b, 5d of ribs Tread end side land portions 6a, 6b of ribs Simulated blocks 7a, 7b Side grooves 8a, 8c First narrow groove portions 8b, 8d Second narrow groove portions 9a, 9b Circumferential narrow grooves 10a to 10d Lateral sipes 11 Tire equator side 12 Tread end side 13 Groove walls 14 of lateral grooves 14 Tire radial direction 15 One end open sipes 16 Notch Part 17 Circumferential auxiliary sipe

Claims (25)

In a pneumatic tire in which at least three main grooves continuously extending in a tire circumferential direction are arranged in a tread portion to form a plurality of rows of ribs,
When considering at least one row of the ribs in the rib in the tire circumferential direction, it is further subdivided into two rows of a tire equatorial side land portion and a tread end side land portion,
The tire equatorial side land part,
A number of lateral grooves extending from the main groove facing it in a direction intersecting the tire circumferential direction,
A circumferential narrow groove comprising a first narrow groove and a second narrow groove intermittently arranged in a staggered manner on two tire circumferences in the rib;
It is disposed between the lateral groove and the circumferential narrow groove when the lateral groove and the circumferential narrow groove are not communicating with each other, and between the first narrow groove and the second narrow groove, and extends in a direction crossing the tire circumferential direction. With horizontal sipes,
Composed of a number of pseudo blocks partitioned by
A pneumatic tire, wherein the rigidity of a land portion on the tire equator side is smaller than the rigidity of a land portion on the tread end side. The pneumatic tire according to claim 1, wherein the lateral groove extends at an angle of 50 to 90 ° with respect to the tire circumferential direction. The pneumatic tire according to claim 1, wherein the lateral groove is a dead end groove having a terminal end in the rib. The pneumatic tire according to claim 3, wherein the lateral groove has a terminal position within a range of 30 to 50% of a rib width from the main groove to be opened. The pneumatic tire according to claim 3, wherein the width of the lateral groove is in a range of 20% to 40% of the width of the main groove. The pneumatic tire according to claim 3, 4 or 5, wherein the lateral groove has a groove depth in a range of 20 to 100% of a groove depth of the main groove. The lateral groove is an open-ended groove communicating with both main grooves, and the land portion rigidity of the rib due to the provision of the lateral groove is smaller at the tire equator side land portion than at the tread end side land portion. The pneumatic tire as described. The pneumatic tire according to claim 7, wherein a depth of the lateral groove decreases from a tire equator side of the rib toward a tread end side. The pneumatic tire according to claim 8, wherein the lateral groove has a groove depth of 25 to 100% on the tire equator side and 10 to 30% on a tread end side with respect to the groove depth of the main groove. . The pneumatic tire according to claim 7, 8 or 9, wherein the width of the lateral groove becomes narrower from the tire equator side to the tread end side of the rib. The pneumatic tire according to claim 10, wherein the width of the lateral groove is 20 to 40% on the tire equator side and 10 to 20% on the tread end side with respect to the groove width of the main groove. 12. The pneumatic tire according to claim 8, wherein an angle of the groove wall with respect to the tire radial direction increases from the tire equator side to the tread end side of the rib. 13. The pneumatic tire according to claim 12, wherein the angle of the groove wall with respect to the tire radial direction is in a range of 0 to 20 degrees on the tire equator side and in a range of 10 to 25 degrees on the tread end side. 14. The separation distance between the first narrow groove portion and the second narrow groove portion of the circumferential narrow groove measured along the tire circumferential direction is in a range of 15 to 50% of the arrangement interval of the lateral groove. 2. The pneumatic tire according to claim 1. 15. The pneumatic pneumatic pump according to claim 1, wherein the circumferential length of each of the first narrow groove portion and the second narrow groove portion in the circumferential narrow groove is in a range of 10 to 45% of the interval between the horizontal grooves. tire. The pneumatic tire according to any one of claims 1 to 15, wherein a groove width of the circumferential narrow groove is in a range of 5 to 25% of a groove width of the main groove. The pneumatic tire according to any one of claims 1 to 16, wherein a groove depth of the circumferential narrow groove is in a range of 20 to 50% of a groove depth of the main groove. The pneumatic tire according to any one of claims 1 to 17, wherein a cut depth of the lateral sipe is substantially the same as a groove depth of the main groove. The pneumatic tire according to any one of claims 1 to 18, wherein a notch is provided at an end of the rib at an equal interval on the tire circumference. The pneumatic tire according to any one of claims 1 to 19, wherein the notch portion has a dimension in the tire width direction in a range of 5 to 15% with respect to the rib width. The pneumatic tire according to any one of claims 1 to 20, wherein the notch portion has a tire circumferential dimension in a range of 10 to 30% with respect to an arrangement interval of the lateral grooves. The pneumatic tire according to any one of claims 1 to 21, wherein the notch has a depth dimension in a range of 80 to 100% with respect to a groove depth of the main groove. The air retire according to any one of claims 1 to 22, wherein one end opening sipe extending in the tire width direction from the main groove is provided at an end of the rib. 24. The pneumatic tire according to claim 23, wherein the one-end opening sipe has a cut length and a circumferentially arranged interval both equal to or less than a groove width of the main groove. The pneumatic tire according to any one of claims 1 to 24, wherein a narrow circumferential auxiliary sipe extending in the tire circumferential direction is provided in a rib defined by the tread end and the circumferential groove.

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