JP2004090769A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for suppressing any partial wear of a shoulder part forming the inner side when the tire is fitted to a vehicle. <P>SOLUTION: At least two circumferential grooves 2 continuously extending in the circumferential direction are formed in a tread. The circumferential rigidity of land part arrays 3 on the end side in the width direction forming the inner side when the tire is fitted to a vehicle out of the land part arrays demarcated by the circumferential grooves 2 is set to be larger than the circumferential rigidity of the land part array 4 on the end side of the width direction forming the outer side when the tire is fitted to the vehicle. A plurality of holes 10 independent from the circumferential grooves are formed in the land part array 3 on the end side in the width direction forming the inner side when the tire is fitted to the vehicle with the maximum depth thereof being ≥ 1/3 of the depth of the circumferential grooves. The volume of the recessed parts of the land part array on the end side in the width direction with respect to the line Ci passing through the center in the width direction of the land part array 3 is set to be larger than the volume of the recessed part of the land part array on the inner side in the width direction of the line passing through the center in the width direction. <P>COPYRIGHT: (C)2004,JPO

Description

【００４８】
表１において、比較例タイヤ１と実施例タイヤ１とを比較すると、実施例タイヤ１は、比較例タイヤ１に較べ、大幅に、車両に装着されて内側となる陸部列の偏摩耗を防止できていることが分かる。
比較例タイヤ１と比較例タイヤ２とを比較すると、車両に装着されて外側となる陸部列の横溝成分を小さくし、細幅周溝を設けて幅方向内側と外側との陸部列部分に分離して、孔を設けると、旋回時の横力を負担しきれず、偏摩耗抑制性能はかえって悪くなる事がわかる。この場合、細幅周溝の外側の陸部列が横力に対しては機能せず、内側陸部列に偏摩耗が発生するため、外観も悪くなる。
【００４９】
実施例タイヤ１と比較例タイヤ５とを比較すると、幅方向内側の陸部列部分に孔を設けることにより、偏摩耗をさらに抑制できていることが分かる。
実施例タイヤ１と実施例タイヤ２とを比較すると、細幅周溝により車両に装着されて内側となる陸部列を幅方向外側と内側に分離することにより、偏摩耗をさらに抑制することができることが分かる。
実施例タイヤ１と比較例タイヤ３とを比較すると、幅方向外側の陸部列部分の幅が大きすぎると、偏摩耗の抑制効果が小さいことが分かる。
実施例タイヤ２と比較例タイヤ４とを比較すると、孔の配列は、幅方向外側の孔の直径を大きくするほうが、偏摩耗を抑制するに際し効果的であることが分かる。
【００５０】
【発明の効果】
以上に述べたところから明らかなように、この発明によれば、トレッドに、その周方向に連続して延びる少なくとも二本の周溝を設け、それらの周溝により区画される陸部列のうち、車両に装着されて内側となる幅方向端側の陸部列の周方向剛性を、車両に装着されて外側となる幅方向端側の陸部列の周方向剛性よりも大きくし、車両に装着されて内側となる幅方向端側の陸部列に周溝から独立した、最大深さが周溝の深さの１／３以上である複数の孔を設け、その陸部列の幅方向中心を通る線に対して幅方向端側の陸部列部分の凹部容積が、幅方向中心を通る線の幅方向内側の陸部列部分の凹部容積より大きくすることにより、装着内側の幅方向端側の陸部列の回転半径が、装着外側の幅方向外側の陸部列の回転半径に較べて小さくなって、装着内側の幅方向端側の陸部列が回転半径の大きい装着外側の幅方向端側の陸部列に対して車両進行方向とは逆方向の力、つまり制動方向の力を受け、偏摩耗が発生することを防止することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図２】本発明のトレッドパターンの一部を示す幅方向断面図である。
【図３】本発明の他の実施の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図４】比較例タイヤの形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図５】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図６】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図７】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図８】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【符号の説明】
１　トレッド部
２　周溝
３　陸部列（装着内側）
４　陸部列（装着外側）
５　横溝
６　陸部列
７　陸部列
８　横溝
９　横溝
１０　孔
１１　細幅周溝
１２　陸部列部分（幅方向外側）
１３　陸部列部分（幅方向内側）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire suitable for use in a passenger car, and particularly proposes a technique for suppressing uneven wear.
[0002]
[Prior art]
In general, in the case of a pneumatic tire, there is often a problem with a front wheel in terms of abrasion of a portion which is mounted on a vehicle and which is inside the vehicle. This is because the original vehicle setting is negative camber or toe-out is relatively large, and the load on the front wheel increases during braking, and the alignment of the front wheel increases negatively and toe-out. It is a factor.
In the case of negative camber, the ground contact length of the shoulder part on the inside of the mounting is longer than the ground contact length of the outside, so if a small slip angle of toe-in or toe-out is added in this state, the lateral displacement of the tire will increase, The shoulder portion inside the mounting portion bears extra lateral force, and this causes uneven wear in which the shoulder portion inside the mounting portion is more worn on the outer shoulder portion.
[0003]
In addition, since the vertical deflection of the shoulder portion on the inner side of the mounting is larger than that of the outer shoulder portion, the width is widened, and the widened region is dragged and receives a force in the braking direction, which also causes uneven wear. .
In addition, the shoulder portion on the inner side of the mounting has a large deflection and a smaller radius of rotation than the outer shoulder portion, so that the shoulder portion is dragged and receives a force in the braking direction. The burden of this force increases in the region closer to the ground contact end, and uneven wear nuclei tend to occur in this region. In this way, uneven wear generated on the shoulder part inside the mounting is difficult to see in the state of mounting on the vehicle and it is difficult for the driver to notice, so if left untreated, the uneven wear will progress In the worst case, there is a possibility that a failure such as a tire burst may occur.
[0004]
[Problems to be solved by the invention]
In order to solve such a problem, the present inventor has proposed a tire in Japanese Patent Application Laid-Open No. 2001-354010 in which the circumferential rigidity of the shoulder portion inside the mounting is larger than the circumferential rigidity of the shoulder portion inside the mounting. did. According to this, when the negative camber was attached, it was possible to suppress an increase in the shearing force in the braking direction inside the mounting, and to suppress uneven wear of the shoulder portion inside the mounting.
[0005]
The present invention is a further improvement of the prior art, and provides a pneumatic tire that can more effectively suppress uneven wear of the shoulder portion on the inner side when mounted.
[0006]
[Means for Solving the Problems]
The pneumatic tire according to the present invention, on the tread, provided at least two circumferential grooves extending continuously in the circumferential direction, of the land portion row defined by those circumferential grooves, mounted on the vehicle inside and The circumferential rigidity of the land portion row on the width direction end side is larger than the circumferential rigidity of the land portion row on the width direction end side that is mounted on the vehicle and becomes outer, and the width direction becomes inner when mounted on the vehicle. A plurality of holes having a maximum depth of 1/3 or more of the depth of the circumferential groove are provided in the land row on the end side, independent of the circumferential groove, and the width is defined with respect to a line passing through the center in the width direction of the land row. The recessed volume of the land row portion on the side of the direction end is larger than the recessed volume of the land row portion on the width direction inner side of the line passing through the center in the width direction.
[0007]
Here, the circumferential rigidity is defined as G = (a × b × E) / (where a is the circumferential length of the land portion, b is the length in the width direction, t is the thickness in the radial direction, and E is the Young's modulus. 3 × t × (1 + ／ (t / a) ² )).
The concave volume is a value obtained by integrating all the volumes of the circumferential groove, the lateral groove, and the hole in each of the land row portions on the end side in the width direction and on the inner side over the entire circumference of the tire.
Further, the circumferential groove is a groove extending in the tire circumferential direction having a width of 2.5% or more of the tread width.
[0008]
Here, the tread width refers to a contact width when the tire is mounted on the applicable rim, a specified air pressure is charged, and a mass corresponding to the maximum load capacity is applied thereto. Here, the applicable rim means the rim specified in the following standard, the maximum load capacity means the maximum mass that can be applied to the tire in the following standard, and the specified air pressure is the following standard Means the air pressure defined corresponding to the maximum load capacity.
The standard is determined by an industrial standard effective in a region where the tire is manufactured or used. For example, in the United States "The Tire and Rim Association Inc., Year Book", in Europe, "The European Tire and Rim Technical Organization, Standards Manual";
[0009]
By making the circumferential rigidity of the land portion row on the width direction end side on the inner side of the mounting larger than the circumferential rigidity of the land portion row on the width direction end side on the outer side of the mounting, when the negative camber is provided, The turning radius of the land row at the end in the width direction is smaller than the turning radius of the land row at the end in the width direction outside the mounting, and the land row at the width end at the inside of the mounting is It is possible to prevent uneven wear from being generated by receiving a force relative to the shoulder portion in the direction opposite to the vehicle traveling direction, that is, in the braking direction.
[0010]
In addition, by providing a plurality of holes having a maximum depth of 1/3 or more of the depth of the circumferential groove independent of the circumferential groove, a plurality of holes are provided in the land portion row on the width direction end side which is mounted on the vehicle and located inside. When the lateral force increases by reducing the shear stiffness of the area provided with, the load of the lateral force in this area is reduced, the generation of the reaction force against the lateral force is suppressed, and this area is braked. Even in the case of being dragged in the direction, generation of a reaction force to the force in the braking direction can be suppressed, and occurrence of uneven wear can be suppressed. Further, by setting the maximum depth of the holes to be at least 1/3 of the depth of the circumferential groove, even if the wear of the tire progresses, the effect of suppressing the occurrence of uneven wear by providing a plurality of holes is ensured. be able to.
Furthermore, by making the recessed volume larger in the land portion row portion in the width direction outside the center line of the land portion row inside the mounting than in the land portion row portion in the width direction inward from the center line, uneven wear is likely to occur in the width direction. On the outside, the effect of suppressing uneven wear can be enhanced.
[0011]
Further, preferably, the land portion row on the width direction end side which is attached to the vehicle and becomes inside is divided into a land portion row portion on the outside in the width direction and a land portion row portion on the inside in the width direction by the narrow width circumferential groove. The width of the land row portion on the outer side in the width direction is made smaller than the width of the land row portion on the inner side in the width direction, and is set to 1/10 or less of the tread width.
[0012]
According to this, it is possible to separate the land portion near the ground end where the uneven wear is most likely to occur from the land row, and suppress the progress of wear to the land row located inside the land section. Here, the width of the land portion row portion on the outer side in the width direction is smaller than the width of the land portion row portion on the inner side in the width direction and is set to 1/10 or less of the tread width, so that uneven wear volume is reduced and the appearance is kept good. be able to.
Here, the narrow circumferential groove is a groove having a width of less than 2.5% of the tread width and extending in the tire circumferential direction.
[0013]
More preferably, at least one of the centers of curvature of the outer contour shape in the cross section in the tire width direction of the outer surface of the land portion row portion on the outer side in the width direction is positioned outside the contour line, while the width direction The center of curvature of the outer contour shape of the inner land row portion is located inside the contour line.
[0014]
According to this, it is possible to reduce the uneven wear volume of the land portion row portion on the width direction outer side in the land portion row on the width direction end side which is attached to the vehicle and becomes inside, and it is possible to maintain good appearance.
[0015]
Here, it is preferable that the width of the narrow circumferential groove is gradually increased from the groove bottom toward the tread surface side.
[0016]
According to this, even when the narrow circumferential groove has caught foreign matter such as pebbles on the road surface, the foreign matter is easily released, and traveling while holding the foreign matter causes the uneven wear nuclei to become inward in the width direction. This can be prevented from occurring in the land row portion of the vehicle.
Here, it is preferable to arrange the narrow circumferential groove only inside the mounting. When placed on the outside of the mounting, the effect of lateral force is large, so the land row on the outer side in the width direction of the circumferential groove can exert the effect of suppressing the progress of wear to the land section on the inner side in the width direction. This is because it is not possible to cause uneven wear directly on the land row in the width direction.
[0017]
Further, under the action of a load of 70% or more of the maximum load capacity of the tire, at least a part of a region where a plurality of holes are arranged in a land portion row on a width direction end side which is mounted on the vehicle and which is inside is grounded. It is preferred to configure the tread so that
[0018]
According to this, even when the rear wheel load is smaller than the front wheel and the contact width becomes smaller, for example, as in the case of the rear wheel at the time of braking of an FF vehicle, a hole is formed in the land portion row on the width direction end side inside the mounting. It is possible to ensure the effect of suppressing the occurrence and progress of uneven wear due to the provision of.
Here, the maximum load capacity refers to a maximum load allowed to be applied to the tire under prescribed conditions such as JATMA, ETRTO, and TRA.
[0019]
More preferably, the opening dimension of the hole is increased as the distance from the tire equator line increases in the land row on the width direction end side which is mounted on the vehicle and located inside.
[0020]
According to this, the effect of suppressing the occurrence and development of uneven wear by providing the above-described holes can be increased as approaching the ground contact end where the load of the lateral force and the braking force is large. In addition, by arranging holes in the area that is effective in suppressing uneven wear and by arranging as little as possible in other parts, maintaining good steering stability and tread durability in other parts Becomes possible.
[0021]
Here, in the land portion row on the width direction end side which is mounted on the vehicle and located inside, it is preferable that the distance between the plurality of holes is reduced as the distance from the tire equator line increases.
[0022]
In this way, the effect of suppressing uneven wear can be increased near the ground contact edge, and holes are arranged only in areas that are effective in suppressing uneven wear, so that steering stability and tread durability of other parts are Properties can be kept good.
[0023]
More preferably, the depth of the hole is increased as the distance from the tire equator line increases in a land portion row on the width direction end side which is mounted on the vehicle and located inside.
[0024]
In this way, the effect of suppressing uneven wear can be increased near the ground contact edge, and holes are arranged only in areas that are effective in suppressing uneven wear, so that steering stability and tread durability of other parts are Properties can be kept good.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded view of a tread pattern showing an embodiment of the present invention in a front view of a tire mounted on a vehicle. Since the internal structure of the tire is the same as that of a general radial tire, illustration is omitted here. The tread 1 is provided with at least two, three in the figure, circumferential grooves 2 extending continuously in the circumferential direction, and is mounted inside a vehicle in a row of land sections defined by the circumferential grooves 2. Of the land portion row 3 on the width direction end side and the land portion row 4 on the width direction end side mounted on the vehicle and being outside, the land portion row 4 is provided with a lateral groove 5, and the periphery of the land portion row 3 is provided. The lateral stiffness is set to be greater than the circumferential stiffness of the land portion row 4, and the other two land portion rows 6 and 7 defined between the three circumferential grooves are provided with lateral grooves 8 and 9, respectively. Can be
Further, a plurality of holes 10 independent of the circumferential groove 2 are provided in the land portion row 3, and the concave volume of the land portion row portion outside the center line Ci in the width direction from the center line Ci of the land portion row 3 is set inside the width direction of the center line. Is larger than the volume of the concave portion of the land row portion.
[0026]
According to this, by making the circumferential rigidity of the land part row 3 larger than the circumferential rigidity of the land part row 4, the land part row 3 is compressed and deformed in the ground contact surface, and the ground contact length becomes longer. The lateral groove shrinks, the radius of gyration decreases, and the shoulder in the land portion row 4 having a large radius of gyration receives a force in the direction opposite to the vehicle traveling direction, that is, a force in the braking direction, causing uneven wear. This can be prevented from occurring.
In addition, by reducing the number of lateral grooves in the land row 3, the number of circumferential geometric discontinuities can be reduced, and heel and toe wear, which is uneven wear in the circumferential direction, can also be suppressed. .
[0027]
Also, by providing the lateral grooves 8, 9 also in the two land sections 6, 7, which are partitioned inward in the width direction from the land sections 3, 4, by the three circumferential grooves 2, the groove edges thereof are provided. Can effectively contribute to the increase in the braking force and the driving force, and at the same time, the drainage performance in the central region of the tread can be improved.
[0028]
These holes 10 reduce the shear stiffness of the area where they are provided, reduce the load on this area for lateral forces, suppress the generation of reaction forces, and also cause this area to be dragged in the braking direction. Also in this case, it is possible to suppress the occurrence of a reaction force against the braking force and to suppress the occurrence of uneven wear.
[0029]
Further, by setting the maximum depth of the holes 10 to be at least 1/3 of the depth of the circumferential groove 2, even when the wear of the tire progresses, the effect of suppressing the occurrence of uneven wear by providing the plurality of holes 10 is provided. Can be secured.
Furthermore, uneven wear is likely to occur by making the recessed volume larger in the land row portion in the width direction outside the center line Ci of the land row inside the mounting than in the land row portion in the width direction inside the center line Ci. On the outer side in the width direction, the effect of suppressing uneven wear can be enhanced.
[0030]
Also, preferably, the land portion row 3 on the width direction end side which is mounted on the vehicle and becomes inside is formed into a land portion row portion 12 on the outside in the width direction and a land portion row portion 13 on the inside in the width direction by the narrow circumferential groove 11. The width w of the land row portion 12 on the outer side in the width direction is made smaller than the width w0 of the land row portion 13 on the inner side in the width direction, and is set to 1/10 or less of the tread width W.
[0031]
According to this, the land row portion 12 on the outer side in the width direction near the grounding end where uneven wear is most likely to occur can be separated, and the progress of wear on the land row portion 13 inside the width can be suppressed. . Further, by making the width w of the land portion row portion 12 outside in the width direction smaller than the width w0 of the land portion row portion 13 inside in the width direction and 1/10 or less of the tread width W, the uneven wear volume is reduced. The appearance can be kept good.
[0032]
More preferably, as shown in FIG. 2, at least one center of curvature C1 of the outer contour shape in the cross section in the tire width direction, the outer surface of the land portion row portion 12 on the outer side in the width direction, is outside the contour line S1. On the other hand, the center of curvature C2 of the outer contour shape of the land portion row portion 13 on the inner side in the width direction is located inside the contour line S2.
[0033]
According to this, the uneven wear volume of the land portion row portion 12 in the width direction outside near the ground end where the uneven wear is most likely to occur can be further reduced, and the appearance can be kept good.
[0034]
Here, the width w10 of the narrow circumferential groove 11 is preferably gradually increased from the groove bottom toward the tread surface side as shown in FIG.
[0035]
According to this, even when the narrow circumferential groove 11 has caught foreign matter such as pebbles on the road surface, the foreign matter is easily released, and the uneven wear nucleus is formed in the width direction by running while holding the foreign matter. It is possible to prevent occurrence on the inner land row portion 13.
[0036]
Further, at least a part of the area where the plurality of holes 10 are arranged in the land row portion 13 in the width direction inside of the land row 3 on the inner side under the action of a load of 70% or more of the maximum load capacity of the tire. Preferably, the tread is configured such that it is grounded.
[0037]
According to this, even if the load is lower than the front wheels and the contact width is small, for example, as in the case of the rear wheels of an FF vehicle, uneven wear can be generated by contacting the formation region of the plurality of holes 10 described above with the ground. The effect of suppressing progress can be guaranteed.
[0038]
More preferably, in the land row portion 13 in the width direction inside of the land row 3 on the inside of the mounting, the opening dimension R of the hole 10 is increased as the distance from the tire equator increases.
[0039]
According to this, the effect of suppressing the occurrence and development of uneven wear by providing the plurality of holes 10 described above can be increased as approaching the ground end where the load of the lateral force and the braking force is large. Further, by arranging the holes 10 in an area effective for suppressing uneven wear and by arranging the holes 10 as little as possible in other parts, the steering stability and tread durability are kept good in other parts. It becomes possible.
[0040]
Further, preferably, in the land portion row portion 13 on the inner side in the width direction of the land portion row 3 on the inner side of the mounting, the distance Q between the plurality of holes 10 decreases as the distance from the tire equator increases.
[0041]
In this way, the effect of suppressing uneven wear can be increased near the grounding end, and multiple holes are arranged only in the area effective for suppressing uneven wear to improve steering stability and tread durability. Can be kept.
[0042]
Preferably, the depth of the hole 10 is increased as the distance from the tire equator increases.
[0043]
In this way, the effect of suppressing uneven wear can be increased near the grounding end, and a plurality of holes 10 are arranged only in an area effective for suppressing uneven wear to improve steering stability and tread durability. Can be kept good.
[0044]
【Example】
For the purpose of evaluating the uneven wear suppressing performance of the pneumatic tire according to one embodiment of the present invention, two types of example tires having a size of 205/65 R15 and five types of comparative example tires are called. Attached to a 6J x 15 rim, the tire filling air pressure was set to 220 kPa, the tire was attached to a test vehicle, and after traveling 30,000 km, the abrasion of the tread portion inside the attachment was measured to evaluate the performance of suppressing uneven wear. Was done. Table 1 shows the results.
In the tread pattern of the first embodiment, as shown in FIG. 1, at least two, three in the figure, circumferential grooves 2 extending continuously in the circumferential direction are provided on a tread 1, and the tread 1 is partitioned by the circumferential grooves 2. Of the land portion rows, the land portion row 3 on the width direction end side which is mounted on the vehicle and becomes inside, and the land portion row 4 which is mounted on the vehicle and the width side end side which becomes the outside side. The row 4 is provided with a lateral groove 5 so that the circumferential rigidity of the land row 3 is greater than the circumferential rigidity of the land row 4, and the other two land rows partitioned between the three circumferential grooves. 6 and 7 are also provided with lateral grooves 8 and 9 respectively, and the land part row 3 is provided with a plurality of holes 10 independent of the circumferential groove 2, and the land part on the outside in the width direction from the center line Ci of the land part row 3. The recessed volume of the row portion is made larger than the recessed volume of the land row portion in the width direction inside of the center line, and the The land portion row 3 on the end side is divided into a land portion row portion 11 on the outside in the width direction and a land portion row portion 12 on the inside in the width direction by the narrow circumferential groove 10, and the land portion row portion 11 on the outside in the width direction is divided. Is smaller than the width of the land portion row portion 12 on the inner side in the width direction, and is 1/10 or less of the tread width.
[0045]
The depth of the narrow circumferential groove 10 is 5.0 mm, the width at the groove bottom is 1.5 mm, and the width at the tread surface is 3.0 mm. The width of the land row portion 11 is 2 mm, and the width of the land row portion 12 is 18 mm.
A plurality of holes 13 independent of the circumferential groove 2 and the narrow circumferential groove 10 are provided in a land row portion 8 on the inner side in the width direction of the land row which is mounted on the vehicle and becomes inner side. The plurality of holes 13 are composed of two rows of holes, the outer hole in the width direction has a diameter of 2.5 mm, the depth is 6 mm, the center-to-center distance is 7.5 mm, and the inner hole in the width direction has a diameter of 1 mm. 0.5 mm, the depth is 6 mm, and the center-to-center distance is 7.5 mm.
[0046]
As shown in FIG. 3, the tread pattern of the second embodiment is based on the first embodiment without providing a narrow circumferential groove, and has a diameter of 2.5 mm, a depth of 6 mm, and a center-to-center distance of 7 at that position. A hole array of 0.5 mm was provided.
As shown in FIG. 4, the tread pattern of Comparative Example 1 does not have a lateral groove on the land portion row on the outer side in the width direction on the outer side of the mounting, and has a lateral groove on the land portion row on the outer side in the width direction on the inner side of the mounting. It is.
As shown in FIG. 5, the tread pattern of Comparative Example 2 is the one in which the tread pattern shown in Example 1 is reversed between the outer side and the inner side.
As shown in FIG. 6, the tread pattern of Comparative Example 3 is based on Example 1, and the width of the land portion row portion 11 on the outer side in the width direction is 14 mm, and the width of the land portion row portion 8 on the inner side in the width direction is 6 mm. The land row portion 12 is provided with a hole row having a diameter of 2.5 mm, a depth of 6 mm and a center-to-center distance of 7.5 mm.
As shown in FIG. 7, the tread pattern of Comparative Example 4 is based on Example 1 without providing a narrow circumferential groove, having a diameter of 3.0 mm, a depth of 6 mm, and a center-to-center distance of 7.5 mm. A row, a row of holes having a diameter of 2.0 mm, a depth of 6 mm, and a center-to-center distance of 7.5 mm, and a row of holes having a diameter of 1.0 mm, a depth of 6 mm, and a center-to-center distance of 7.5 mm, They are provided in this order from the inside in the width direction.
As shown in FIG. 8, the tread pattern of Comparative Example 5 is based on Example 1 and does not have a plurality of holes.
In the performance evaluation, Comparative Example Tire 1 was used as a control tire, and was evaluated out of 100 points. The smaller the value, the better.
[0047]
[Table 1]

[0048]
In Table 1, when the comparative example tire 1 and the example tire 1 are compared, the example tire 1 significantly prevents uneven wear of the land portion row which is mounted on the vehicle and located inside as compared with the comparative example tire 1. You can see that it is done.
When the comparative example tire 1 and the comparative example tire 2 are compared with each other, the lateral groove component of the land portion row which is mounted on the vehicle and which becomes the outside is reduced, and the narrow circumferential groove is provided to form the land portion row portion between the inside and the outside in the width direction. It can be seen that when the holes are provided separately, the lateral force during turning cannot be fully covered, and the uneven wear suppressing performance is rather deteriorated. In this case, the land portion row outside the narrow circumferential groove does not function with respect to the lateral force, and uneven wear occurs on the inner land row, so that the appearance is deteriorated.
[0049]
Comparing Example tire 1 with Comparative example tire 5, it can be seen that uneven wear can be further suppressed by providing a hole in the land row portion on the inner side in the width direction.
Comparing Example Tire 1 with Example Tire 2, it is possible to further suppress uneven wear by separating the land portion row, which is attached to the vehicle and becomes inside by the narrow circumferential groove, into the outside and inside in the width direction. You can see what you can do.
Comparing Example tire 1 with Comparative example tire 3, it can be seen that if the width of the land portion row portion outside in the width direction is too large, the effect of suppressing uneven wear is small.
Comparing the example tire 2 with the comparative example tire 4, it can be seen that the arrangement of the holes is more effective in suppressing uneven wear by increasing the diameter of the holes on the outer side in the width direction.
[0050]
【The invention's effect】
As is apparent from the above description, according to the present invention, the tread is provided with at least two circumferential grooves extending continuously in the circumferential direction, and the land portion row defined by those circumferential grooves is The circumferential rigidity of the land portion row on the width direction end side which is mounted on the vehicle and becomes inner side is made larger than the circumferential rigidity of the land portion row on the width direction end side which is mounted on the vehicle and becomes outer side. A plurality of holes, each having a maximum depth of 1/3 or more of the depth of the circumferential groove, are provided in the land portion row on the width direction end side, which is mounted inside, and is independent of the circumferential groove. By making the concave volume of the land row portion on the width direction end side with respect to the line passing through the center larger than the concave volume of the land row portion inside the width direction of the line passing through the center in the width direction, the width direction inside the mounting The radius of rotation of the land row on the end side is smaller than the radius of rotation of the land row on the outer side in the width direction on the outside of the installation. Land rows at the inner width direction end on the inside receive a force in the direction opposite to the vehicle traveling direction, that is, forces in the braking direction, against the land row at the outer width direction end on the outside with a large turning radius, causing uneven wear. Can be prevented from occurring.
[Brief description of the drawings]
FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention in a front view of a tire in a mounting posture to a vehicle.
FIG. 2 is a cross-sectional view in the width direction showing a part of the tread pattern of the present invention.
FIG. 3 is a development view of a tread pattern showing another embodiment of the present invention in a front view of a tire in a mounting posture to a vehicle.
FIG. 4 is a development view of a tread pattern showing the form of the comparative tire in a front view of the tire in a mounting posture to a vehicle.
FIG. 5 is a development view of a tread pattern showing another form of the comparative example tire in a front view of the tire in a mounting posture to a vehicle.
FIG. 6 is a developed view of a tread pattern showing another form of the comparative tire in a front view of the tire in a mounting posture to a vehicle.
FIG. 7 is a development view of a tread pattern showing another form of the comparative tire in a front view of the tire in a mounting posture to a vehicle.
FIG. 8 is a developed view of a tread pattern showing another form of the comparative tire in a front view of the tire in a mounting posture to a vehicle.
[Explanation of symbols]
1 Tread part 2 Circumferential groove 3 Land line (inside of mounting)
4 Land row (outside wearing)
5 Side groove 6 Land part row 7 Land part row 8 Side groove 9 Horizontal groove 10 Hole 11 Narrow peripheral groove 12 Land part row part (width direction outside)
13 Land row part (width direction inside)

Claims (8)

The tread is provided with at least two circumferential grooves extending continuously in the circumferential direction, and among the land part rows defined by those circumferential grooves, the land part row on the width direction end side which is mounted on the vehicle and becomes inside. The circumferential stiffness of the land portion row on the width direction end side which is mounted on the vehicle and becomes the outside is larger than that of the land portion row on the width direction end side which is mounted on the vehicle and becomes the inside. And a plurality of holes each having a maximum depth of 1/3 or more of the depth of the circumferential groove are provided independently of the land portion row portion on the width direction end side with respect to a line passing through the width direction center of the land portion row. A pneumatic tire in which a concave volume is larger than a concave volume of a land row portion on the inner side in the width direction of a line passing through the center in the width direction. The land portion row at the end in the width direction, which is attached to the vehicle and becomes inside, is divided into a land portion row portion on the outside in the width direction and a land portion row on the inside in the width direction by a narrow circumferential groove, and the outer side in the width direction. 2. The pneumatic tire according to claim 1, wherein the width of the land row portion is smaller than the width of the land row portion on the inner side in the width direction and is 1/10 or less of the tread width. At least one of the centers of curvature of the outer contour shape in the cross section in the tire width direction of the outer surface of the width direction outer land portion row portion is located outside the contour line, while the width direction inner land portion. The pneumatic tire according to claim 2, wherein the center of curvature of the outer contour shape of the row portion is located inside the contour line. The pneumatic tire according to any one of claims 2 to 3, wherein the width of the narrow circumferential groove is gradually increased from the groove bottom toward the tread surface side. Under the action of a load of 70% or more of the maximum load capacity of the tire, at least a part of the area where the plurality of holes are arranged in the land portion row on the widthwise end side which is mounted on the vehicle and which is inside is grounded. The pneumatic tire according to any one of claims 1 to 4, wherein the tread comprises a tread. The pneumatic tire according to any one of claims 1 to 5, wherein in a land portion row on the inner side in the width direction, which is mounted on the vehicle, the opening dimension of the hole increases as the distance from the tire equator increases. The pneumatic tire according to any one of claims 1 to 6, wherein a distance between the plurality of holes is reduced as the distance from the tire equator is reduced in a land portion row on a width direction end side which is mounted inside the vehicle. The pneumatic tire according to any one of claims 1 to 7, wherein a depth of the hole is increased as the distance from the tire equator is increased in a land portion row on a width direction end side which is mounted inside the vehicle.

Images