WO2021085005A1

WO2021085005A1 - Pneumatic tire

Info

Publication number: WO2021085005A1
Application number: PCT/JP2020/036756
Authority: WO
Inventors: 孝志芝井
Original assignee: 横浜ゴム株式会社
Priority date: 2019-11-01
Filing date: 2020-09-29
Publication date: 2021-05-06
Also published as: FI20225425A1; FI130329B; CN114599528B; JP7172954B2; CN114599528A; JP2021070450A

Abstract

Provided is a pneumatic tire that has stud pins implanted on a tread surface of a tread part and that enables improvement of performance on ice and improvement of ride quality performance on a dry road surface. This pneumatic tire has stud pins P implanted on a tread surface of a tread part 1. When a region demarcated between a pair of tire meridians arranged such that a gap therebetween on a tire center line CL is 1/4 of a tire ground contact length is defined as a belt-like region A and a plurality of the belt-like regions A are arranged on the whole tire circumference at an angular interval of 1 degree along a tire circumferential direction, a number n of the stud pins P included in each belt-like region A of all the plurality of belt-like regions A is not more than 4.0% of a total number N of the stud pins P in the whole tire circumference and the number n of the stud pins included in each belt-like region A of not less than 2/3 of the plurality of belt-like regions A is not less than 2.0% of the total number N.

Description

Pneumatic tires

The present invention relates to a pneumatic tire in which a stud pin is planted on the tread of a tread portion.

In severe winter areas such as Scandinavia and Russia, studless tires are mainly used as winter tires. In the stud tire, a plurality of implantation holes for implanting the stud pins are provided in the tread portion, and the stud pins are implanted in these implantation holes (see, for example, Patent Document 1). Such a stud pin exerts an effect of scratching the ice-snow road surface when traveling on the ice-snow road surface, so that the performance on ice can be improved. On the other hand, when traveling on a road surface other than ice and snow (particularly on a dry paved road surface), the impact of the hard stud pin hitting the paved road surface is transmitted as a shock feeling, which may cause deterioration of riding comfort. And even in the winter season in the severe winter region, there is an opportunity to drive on paved road surfaces (dry road surfaces) other than ice and snow road surfaces at a considerable frequency. Therefore, in stud tires, measures are required to improve the riding comfort performance on a dry road surface while effectively exhibiting the running performance (particularly, the traction performance on ice) on an ice-snow road surface.

Japanese Patent Application Laid-Open No. 2018-187960

An object of the present invention is to provide a pneumatic tire in which a stud pin is planted on a tread portion of a tread portion, which makes it possible to improve riding comfort performance on a dry road surface while improving performance on ice. There is.

The pneumatic tire of the present invention that achieves the above object has a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a tire of these sidewall portions. In a pneumatic tire having a pair of bead portions arranged radially inside and stud pins planted on the tread of the tread portion, the distance on the tire equatorial line is arranged so as to be 1/4 of the tire contact length. When the region partitioned between the pair of tire meridional lines is defined as a band-shaped region and the plurality of strip-shaped regions are arranged over the entire circumference of the tire by shifting the angle by 1 degree along the tire circumferential direction, the plurality of strip-shaped regions The number n of stud pins included in each band-shaped region in all of the regions is 4.0% or less of the total number N of stud pins in the entire circumference of the tire, and the strip-shaped region is 2/3 or more of the plurality of strip-shaped regions. The number n of stud pins included in the above is 2.0% or more of the total number N.

In the present invention, by providing the stud pin as described above, it is possible to effectively enhance the performance on ice and to satisfactorily exhibit the riding comfort performance on a dry road surface. Specifically, in all the strip-shaped regions, the ratio of the number n of the stud pins to the total number N of the stud pins is suppressed to 4.0% or less, so that the stud pins come into contact with the road surface when traveling on a dry road surface. It is possible to suppress the feeling of shock when doing so, and it is possible to improve the riding comfort performance. On the other hand, the ratio of the number n of stud pins to the total number N of stud pins N is set to an appropriate range of 2.0% or more, and a strip-shaped region is sufficiently provided all around the tire, so that the performance on ice is good. Can be demonstrated.

In the present invention, the total number of stud pins is preferably 135 to 250. By providing an appropriate number of stud pins in this way, it is advantageous to improve the riding comfort performance on a dry road surface while effectively exhibiting the performance on ice.

In the present invention, among the plurality of strip-shaped regions, there is one or more concentrated regions in which the number n of stud pins included in the strip-shaped region is 3.0% or more of the total number of N, and among the plurality of strip-shaped regions. It is preferably present in 1/3 or less of. In this way, by providing a concentrated region having a large number of stud pins and excellent on-ice performance, it is possible to further improve the on-ice performance. On the other hand, since the number of concentrated regions is suppressed to 1/3 or less of the plurality of strip-shaped regions, the riding comfort performance on a dry road surface can be satisfactorily exhibited even if the concentrated regions are provided.

At this time, in the concentrated region, there are two or more dense regions in which the number n of stud pins included in the strip-shaped region is 3.5% or more of the total number N, and the dense regions adjacent to each other in the tire circumferential direction. It is preferable that the interval between the tires is 100% or more of the tire contact length. Since the dense area is particularly excellent in the performance on ice among the concentrated areas, it is possible to further improve the performance on ice. On the other hand, since the distance between the dense areas is larger than the tire contact patch length, the number of dense areas existing in the contact patch when the tire rolls is always one or less, and even if the dense area is provided, riding on a dry road surface Comfortable performance can be exhibited well.

Further, it is preferable that the average protrusion amount Px of the stud pins included in the concentrated region and the average protrusion amount Pav of the stud pins in the region excluding the concentrated region satisfy the relationship of Px ≦ 0.9 × Pav. By setting the amount of protrusion of the stud pins in this way, the amount of protrusion of the stud pins can be kept low in the concentrated region where the number of stud pins is relatively large, and the riding comfort performance on a dry road surface can be exhibited well. Will be advantageous.

In the present invention, among the regions in which the tread portion of the tread portion is divided into three equal parts in the tire width direction, the region located on the equator of the tire is defined as the center region, and the pair of regions located on both sides of the center region in the tire width direction are shoulder shoulders. In terms of the region, it is preferable that at least one stud pin is present in each of the center region and the pair of shoulder regions in the band-shaped region in which the number n of stud pins is 3 or more. By arranging the stud pins in a dispersed manner in the tire width direction in this way, it is possible to efficiently obtain a force for scratching the ice and snow road surface in the entire area in the tire width direction, which is advantageous for improving the performance on ice. In addition, the uniformity in the tire width direction can be improved.

In the present invention, the "ground contact length" is the tire equatorial line of the ground contact region formed when the tire is rim-assembled on the regular rim, placed vertically on a flat surface with the regular internal pressure charged, and a regular load is applied. Is the length in the tire circumferential direction. Further, the "ground contact ends" are both ends of the above-mentioned ground contact region in the tire axial direction. A "regular rim" is a rim defined for each tire in a standard system including a standard on which a tire is based. For example, a standard rim for JATTA, a "Design Rim" for TRA, or an ETRTO. If so, use "Measuring Rim". "Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. If it is JATTA, it is the maximum air pressure, and if it is TRA, it is the table "TIRE LOAD LIMITED AT VARIOUS". The maximum value described in "COLD INFLATION PRESSURES", if it is ETRTO, it is "INFRATION PRESSURE", but if the tire is for a passenger car, it is 250 kPa. "Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. If it is JATTA, it is the maximum load capacity, and if it is TRA, it is the table "TIRE LOAD LIMITED AT VARIOUS". The maximum value described in "COLD INFLATION PRESSURES" is "LOAD CAPACITY" in the case of ETRTO, but when the tire is for a passenger car, the load is equivalent to 80% of the above load.

FIG. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a front view showing a tread surface of a pneumatic tire according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of a stud pin planted in a tread portion. FIG. 4 is an explanatory diagram schematically showing a change in the number of stud pins for each strip-shaped region.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the pneumatic tire of the present invention is arranged inside the tread portion 1, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and the sidewall portion 2 in the tire radial direction. It is provided with a pair of bead portions 3. In FIG. 1, reference numeral CL indicates a tire equator, and reference numeral E indicates a ground contact end. Although FIG. 1 is a cross-sectional view of the meridian, the tread portion 1, the sidewall portion 2, and the bead portion 3 each extend in the tire circumferential direction to form an annular shape, whereby the pneumatic tire is formed. The toroidal basic structure of is constructed. Hereinafter, the description using FIG. 1 is basically based on the illustrated meridian cross-sectional shape, but each tire component extends in the tire circumferential direction to form an annular shape.

A carcass layer 4 is mounted between the pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inside to the outside of the vehicle around the bead cores 5 arranged in each bead portion 3. Further, a bead filler 6 is arranged on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by a main body portion and a folded portion of the carcass layer 4. On the other hand, a plurality of layers (two layers in FIG. 1) of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in the range of, for example, 10 ° to 40 °. Further, a belt reinforcing layer 8 is provided on the outer peripheral side of the belt layer 7. The belt reinforcing layer 8 contains an organic fiber cord oriented in the tire circumferential direction. In the belt reinforcing layer 8, the angle of the organic fiber cord with respect to the tire circumferential direction is set to, for example, 0 ° to 5 °.

The present invention is applied to a pneumatic tire having such a general cross-sectional structure, but the basic structure thereof is not limited to the above. Further, since the present invention relates to the arrangement of the stud pin P in the pneumatic tire in which the stud pin P is planted on the tread surface of the tread portion 1, the structure of the groove and the land portion formed on the surface of the tread portion 1 (Tread pattern) is not particularly limited.

The pneumatic tire shown in FIG. 2 has a plurality of lug grooves 11 extending along the tire width direction and a plurality of circumferential grooves 12 extending along the tire circumferential direction. The portion 13 has a partitioned tread pattern. In the illustrated example, the lug groove 11 extends inclined with respect to the tire width direction, one end is located on the tire equatorial CL, and the other end extends beyond the ground contact end E on one side in the tire width direction. The existing first lug groove 11a extends at an angle with respect to the tire width direction, one end is located on the tire equatorial CL, and the other end extends beyond the contact end E on the other side in the tire width direction. The second lug groove 11b is included. In the first lug groove 11a and the second lug groove 11b, one end of the first lug groove 11a and one end of the second lug groove 11b are alternately arranged in the tire circumferential direction on the tire equator CL, and the first lug groove 11a and the second lug groove 11b are arranged in the tire circumferential direction. The 11a and the second lug groove 11b are arranged so as to form a substantially V shape. The circumferential groove 12 extends so as to be inclined with respect to the tire circumferential direction so as to connect the adjacent lug grooves 11 in the tire circumferential direction in the middle portion of each lug groove 11 in the length direction. The center land portion 13a is partitioned inside the tire width direction of the circumferential groove 12, and the shoulder land portion 13b (shoulder block) is partitioned outside the tire width direction of the circumferential groove 12. Further, in the illustrated example, one end communicates with the circumferential groove 12 in the middle portion in the length direction of each circumferential groove 12, extends from the circumferential groove 12 toward the tire equator CL side, and the other end ends. An auxiliary groove 14 is provided that terminates within the center land portion 13a. Further, each land portion 13 is provided with a plurality of sipes 14. The stud pin P can be planted on any land portion 13.

The stud pin P is planted in the stud pin implantation hole provided on the tread surface of the tread portion 1. The stud pin P is planted by inserting the stud pin P into the hole with the planting hole expanded and then releasing the expansion of the planting hole. FIG. 3 is a cross-sectional view schematically showing a state in which the stud pin P is planted in the implantation hole of the tread portion 1. In the illustrated example, the double flange type stud pin P is described as the stud pin P, but a stud pin P having a different structure such as a single flange type can also be used.

As illustrated in FIG. 3, the stud pin P is composed of a columnar body portion P1, a tread side flange portion P2, a bottom side flange portion P3, and a tip portion P4. The tread side flange portion P2 and the bottom side flange portion P3 have a larger diameter than the body portion P1, and the tread side flange portion P2 is formed on the tread surface side (outside in the tire radial direction) of the body portion P1 and the bottom side flange portion. P3 is formed on the bottom side (inside in the tire radial direction) of the body portion P1. The tip portion P4 protrudes outward in the tire radial direction from the tread side flange portion P2 on the pin shaft (center of the stud pin P). Since the tip portion P4 protrudes from the tread surface in a state where the stud pin P is planted in the tread portion 1, it can bite into the ice and snow road surface and exhibits traction on ice. The tip portion P4 is made of a material (for example, a tungsten compound) that is harder than other portions (body portion P1, tread side flange portion P2, bottom side flange portion P3) made of, for example, aluminum or the like. In the present invention, the number of stud pins P included in the strip-shaped region described later is defined, but if at least a part of the tip portion P4 is present in the strip-shaped region described later, the number is counted as the number included in the strip-shaped region. To do.

In the present invention, it is partitioned between a pair of tire meridians arranged so that the distance on the tire equator CL is 1/4 of the tire contact length, regardless of the tread pattern formed on the surface of the tread portion 1. The region is defined as a tread region A (see, for example, the shaded area in FIG. 2). Then, as schematically shown in FIG. 4, a plurality of strip-shaped regions A (A1, A2, A3 ...) Are arranged over the entire circumference of the tire by shifting the angles by 1 degree along the tire circumferential direction. The number n of the stud pins P included in each band-shaped region A (A1, A2, A3 ...) Is measured. Note that FIG. 4 schematically shows the arrangement of the band-shaped region A, and the details of the tread pattern formed in the tread portion 1 and the specific arrangement of the stud pins P are omitted. Further, the strip-shaped region A after the reference numeral A3 is omitted. The reference numeral R in the figure represents the tire circumferential direction.

In all of the plurality of strip-shaped regions A defined in this way, the number n of stud pins P included in each strip-shaped region A is set to 4.0% or less of the total number N of stud pins P in the entire circumference of the tire. .. For example, in the example shown in FIG. 4, the number n of the stud pins P is 7 or less. In the example of FIG. 4, the total number N = 190 is assumed, and 4.0% of the total number N is 7.6. Therefore, the example of FIG. 4 satisfies the above-mentioned condition. Further, also in the example of FIG. 2, assuming that the total number is N = 190, the number n of the stud pins P is 7 or less in each of the three strip-shaped regions A (hatched lines) surrounded by the alternate long and short dash line, which is described above. Meet the conditions of. On the other hand, in two-thirds or more of the plurality of strip-shaped regions A, the number n of stud pins P included in the strip-shaped region A is set to 2.0% or more of the total number N of stud pins P. For example, when the total number N = 190, 2.0% of the total number N is 3.8, so in the example of FIG. 4, the strip-shaped region A provided with four or more stud pins P is a plurality of strips. If it is 2/3 or more of the area A, the above condition is satisfied. As described above, in all the band-shaped regions A, the ratio of the number n of the stud pins P to the total number N of the stud pins P is suppressed to 4.0% or less, so that the stud pins P are suppressed when traveling on a dry road surface. It is possible to suppress the feeling of shock when the vehicle comes into contact with the road surface, and it is possible to improve the riding comfort performance. On the other hand, since the band-shaped region A in which the ratio of the number n of the stud pins P to the total number N of the stud pins P is set to an appropriate range of 2.0% or more is sufficiently provided on the entire circumference of the tire, it is on ice. The performance can be exhibited well.

Further, among the plurality of strip-shaped regions A, a region in which the number n of stud pins P included in the strip-shaped region A is 3.0% or more of the total number N of stud pins P is distinguished as a concentrated region A'. It is preferable that the region A'is present at one or more locations on the tire circumference. In the example shown in FIG. 4, the total number N = 190 is assumed as described above, and 3.0% of the total number N is 5.7. Therefore, in the example of FIG. 4, 6 or more are used. The band-shaped region A provided with the stud pin P corresponds to the concentrated region A'. Further, in the three strip-shaped regions A (hatched portions) shown in FIG. 2, the locations where the number n of the stud pins P is 6 or 7 correspond to the concentrated region A'. In FIG. 2, the portion where the number n of the stud pins P is 7 also corresponds to the dense region A ″ described later, so the reference numeral in the figure is indicated as A (A ″), but this portion is also concentrated. Corresponds to region A'. When a plurality of concentrated regions A'are provided, it is preferable to limit the concentrated region A'to 1/3 or less of the plurality of strip-shaped regions A. In the concentrated region A', the number n of stud pins P is larger than that of the other strip-shaped regions A, and the performance on ice is excellent. Therefore, by providing such a concentrated region A', the performance on ice can be further improved. On the other hand, since the number of concentrated regions A'is suppressed to 1/3 or less of the plurality of strip-shaped regions A, even if the concentrated regions A'are provided, the riding comfort performance on a dry road surface can be satisfactorily exhibited. .. When the number of concentrated areas A'exceeds 1/3 of the plurality of strip-shaped areas A, the concentrated area A'where many stud pins P that can cause a feeling of shock during running increases, so that the riding comfort performance It becomes difficult to exert well.

Further, among the concentrated regions A', if the region in which the number n of the stud pins P included in the band-shaped region is 3.5% or more of the total number N of the stud pins P is distinguished as the dense region A ″, the dense region A It is preferable that "" is present at one or more locations on the tire circumference. In the example shown in FIG. 4, the total number N = 190 is assumed as described above, and 3.5% of the total number N is 6.7. Therefore, in the example of FIG. 4, 7 or more are used. The band-shaped region A provided with the stud pin P corresponds to the concentrated region A'. Further, in the three strip-shaped regions A (hatched portions) shown in FIG. 2, the portion where the number n of the stud pins P is 7 corresponds to the concentrated region A ″. When a plurality of dense regions A ″ are provided, the tire It is preferable that the distance between the dense regions A "adjacent to each other in the circumferential direction is 100% or more of the tire contact length. The dense region A" is particularly excellent in the on-ice performance among the concentrated regions A', so that the on-ice performance can be improved. Can be improved. On the other hand, since the distance between the dense areas A "is larger than the tire contact patch length, the dense area A" existing in the contact patch when the tire rolls is reduced to one or less, and the dense area A "is provided. However, the riding comfort performance on a dry road surface can be satisfactorily exhibited. If the distance between the dense areas A "is less than 100% of the ground contact length, there are many stud pins P that can cause a feeling of shock during running. Since there may be a plurality of dense areas A ″ in the ground plane, it is difficult to achieve good riding comfort. Note that the distance between the dense areas A ″ is the distance between adjacent dense areas A ″. It is the length along the tire circumferential direction between the tire meridians facing each other.

The stud pins P may be arranged as described above, but the total number of stud pins in the entire tire is preferably 135 to 250, more preferably 135 to 200. By providing an appropriate number of stud pins P on the entire tire in this way, it is advantageous to effectively exhibit the performance on ice and to exhibit the ride comfort performance well. If the total number of stud pins is less than 135, the traction performance on ice cannot be sufficiently improved. If the total number of stud pins exceeds 250, the riding comfort performance cannot be fully exhibited.

As shown in FIG. 2, of the regions obtained by dividing the tread surface of the tread portion 1 (the range between the ground contact ends E on both sides in the tire width direction) into three equal parts in the tire width direction, the region located on the tire equator CL is the center region. When Ce is defined and the pair of regions located on both sides of the center region Ce in the tire width direction are shoulder regions Sh, the center region Ce and the pair of shoulders are formed in the band-shaped region A in which the number n of stud pins P is 3 or more. It is preferable that at least one stud pin P is present in each of the regions Sh. By arranging the stud pins in a dispersed manner in the tire width direction in this way, it is possible to efficiently obtain a force for scratching the ice and snow road surface in the entire area in the tire width direction, which is advantageous for improving the performance on ice. In addition, the uniformity in the tire width direction can be improved. For example, when the total number N of the stud pins P is 135, the number n of the stud pins P is 3 or more in the band-shaped region A in which the number n of the stud pins P is 2.0% or more of the total number N (). 135 x 0.020 = 2.7). In this case, if the above-mentioned distributed arrangement of the stud pins P is adopted, at least one stud pin P is provided in each of the center region Ce and the pair of shoulder regions Sh in two-thirds or more of the plurality of strip-shaped regions A. It will be distributed and arranged. Therefore, it is very effective for improving the performance on ice.

The protruding amount h of the stud pin P may be uniform, but the average value of the protruding amount h of the stud pin P included in the concentrated region A'is provided in the region excluding the average protruding amount Px and the concentrated region A'. When the average value of the protrusion amount h of the stud pin P is the average protrusion amount Pav, it is preferable that these satisfy the relationship of Px ≦ 0.9 × Pav. By setting the protruding amount h of the stud pin P in this way, the protruding amount of the stud pin can be suppressed low in the concentrated region A'in which the number of stud pins is relatively large, and the riding comfort performance can be improved. It will be advantageous. Further, from the viewpoint of ensuring sufficient performance on ice, it is preferable to satisfy the relationship of Px ≧ 0.7 × Pav.

Hereinafter, the present invention will be further described with reference to Examples, but the scope of the present invention is not limited to these Examples.

Conventional Example 1, Comparative Examples 1 and 2, which have a tire size of 205 / 55R16 94T, have the basic structure illustrated in FIG. 1, and have the structure set as shown in Table 1 based on the tread pattern of FIG. Eleven types of pneumatic tires of Examples 1 to 8 were produced.

In Table 1, "total number N" is the total number of stud pins provided on the entire tire, and "n" is the number of stud pins included in each dense area. For the "maximum value of n in the belt-shaped region", the condition of the upper limit value defined in the present invention (4.0% of the total number N = 0.04N), the measured value in each tire, and the magnitude relationship between them are displayed. did. In particular, regarding the magnitude relationship, the case where the measured value is equal to or less than the upper limit condition (0.04N) is indicated by “◯”, and the case where the measured value exceeds the upper limit condition (0.04N) is indicated by “x”. The “standard arrangement area” means a band-shaped area in which the number n of stud pins satisfies 2.0% or more of the total number N of stud pins N. Regarding this "standard arrangement area", the condition of the lower limit value defined in the present invention (2.0% of the total number N = 0.02N), the presence or absence of the standard arrangement area, and the ratio of the standard arrangement area to the total band-shaped area. Was displayed. For the "concentrated region", the condition of the lower limit value defined in the present invention (3.0% of the total number N = 0.03N), the presence or absence of the concentrated region, and the ratio of the concentrated region to the total band-shaped region are displayed. Regarding the "dense region", the condition of the lower limit value defined in the present invention (3.5% of the total number N = 0.035N), the presence or absence of the dense region, and the minimum distance between the dense regions adjacent to each other in the tire circumferential direction. (Ratio to ground contact length) is displayed. "Arrangement of stud pins in the width direction" means arrangement of stud pins in the tire width direction in a band-shaped region having three or more studs n, and at least one stud in each of a center region and a pair of shoulder regions. The case where the pin is present is indicated as "dispersion", and the case where the stud pin is not present in either the center area or the pair of shoulder areas is indicated as "uneven distribution". “Px / Pav” is the ratio of the average protrusion amount Px of the stud pins included in the concentrated region to the average protrusion amount Pav of the stud pins provided in the region excluding the concentrated region.

The above-mentioned 11 types of pneumatic tires (conventional example 1, comparative examples 1 to 2, and examples 1 to 8) had a common ground contact length of 120 mm. That is, in each example, the length of the strip-shaped region in the tire circumferential direction (1/4 of the tire contact length) is 30 mm.

These pneumatic tires were evaluated for stability on ice, riding comfort on dry roads, and low vibration on dry roads by the following evaluation methods, and the results are also shown in Table 1.

Stability on ice Steering performance Each test tire is assembled to a wheel with a rim size of 16 x 6.5J, filled with the specified air pressure of the vehicle, mounted on a front-wheel drive vehicle with a displacement of 1.4L, and a test course (turning field) consisting of ice and snow road surfaces. The sensory evaluation of the steering stability performance was performed by a test driver. The evaluation result is shown by an index with the value of Conventional Example 1 as 100. The larger this index value is, the better the stability performance on ice is.

Riding comfort performance on dry roads Each test tire is assembled on a wheel with a rim size of 16 x 6.5J, filled with vehicle-specified air pressure, mounted on a front-wheel drive vehicle with a displacement of 1.4L, and on a test course consisting of dry roads. , The ride comfort performance (shock feeling) was evaluated by a test driver. The evaluation result is shown by an index with the value of Conventional Example 1 as 100. The larger the index value, the smaller the shock feeling, which means that the riding comfort performance on a dry road surface is excellent.

Low vibration performance on dry road surface Each test tire is assembled to a wheel with a rim size of 16 x 6.5J, filled with the specified air pressure of the vehicle, mounted on a front-wheel drive vehicle with a displacement of 1.4L, and on a test course consisting of a dry road surface. , Sensory evaluation of vibration was performed. The evaluation result is shown by an index with the value of Conventional Example 1 as 100. The larger the index value, the smaller the vibration, which means that the low vibration performance on a dry road surface is excellent. It should be noted that the better the low vibration performance, the better the weight balance of the tire and the better the uniformity.

As is clear from Table 1, all of Examples 1 to 8 exhibit better riding comfort performance and low vibration performance on a dry road surface while exhibiting better steering stability performance on ice as compared with Conventional Example 1. However, these performances are highly compatible. On the other hand, in Comparative Example 1, since there are few band-shaped regions in which the number n of stud pins satisfies 2.0% or more of the total number N of stud pins, the stability performance on ice has deteriorated. Since Comparative Example 2 has a band-shaped region in which a number of stud pins larger than 4.0% of the total number N is present, the riding comfort performance and the low vibration performance on a dry road surface are deteriorated.

1 Tread part 2 sidewall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 belt reinforcement layer 11 lug groove 12 circumferential groove 13 land part 14 auxiliary groove 15 sipe P stud pin A band-shaped area A'concentrated area A ″ Dense area Ce Center area Sh Shoulder area CL Tire equator E Grounding edge

Claims

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the tire radial direction of these sidewall portions. In addition, in a pneumatic tire in which a stud pin is planted on the tread of the tread portion,
The area defined between the pair of tire meridians arranged so that the distance on the tire equatorial line is 1/4 of the tire contact length is defined as a band-shaped area, and the plurality of band-shaped areas are set at an angle of 1 along the tire circumferential direction. When the tires are staggered and arranged over the entire circumference of the tire
The number n of stud pins included in each of the plurality of strip regions is 4.0% or less of the total number of stud pins N in the entire circumference of the tire, and 2/3 or more of the plurality of strip regions. The pneumatic tire, wherein the number n of stud pins included in the strip-shaped region is 2.0% or more of the total number N.
The pneumatic tire according to claim 1, wherein the total number of the stud pins is 135 to 250.
Among the plurality of strip-shaped regions, there is one or more concentrated regions in which the number n of stud pins included in the strip-shaped region is 3.0% or more of the total number N, and one of the plurality of strip-shaped regions. The pneumatic tire according to claim 1 or 2, wherein the tire is present in an amount of / 3 or less.
In the concentrated region, there are two or more dense regions in which the number n of stud pins included in the strip-shaped region is 3.5% or more of the total number N, and the dense regions adjacent to each other in the tire circumferential direction. The pneumatic tire according to claim 3, wherein the interval is 100% or more of the tire contact length.
The feature is that the average protrusion amount Px of the stud pin included in the concentrated region and the average protrusion amount Pav of the stud pin in the region excluding the concentrated region satisfy the relationship of Px ≦ 0.9 × Pav. The pneumatic tire according to any one of claims 1 to 4.
Of the regions where the tread portion of the tread portion is divided into three equal parts in the tire width direction, a region located on the tire equator is designated as a center region, and a pair of regions located on both sides of the center region in the tire width direction are designated as shoulder regions. When, any of claims 1 to 5, characterized in that at least one stud pin is present in each of the center region and the pair of shoulder regions in a band-shaped region in which the number n of the stud pins is three or more. Pneumatic tires listed in Crab.