FI20225575A1

FI20225575A1 - Pneumatic tire

Info

Publication number: FI20225575A1
Application number: FI20225575A
Authority: FI
Inventors: Takashi Shibai
Original assignee: Yokohama Rubber Co Ltd
Priority date: 2019-12-10
Filing date: 2020-12-07
Publication date: 2022-06-23
Also published as: JP7393632B2; JP2021091289A; WO2021117678A1

Abstract

Provided is a tire having stud pins implanted in a road contact surface of a tread portion, the pneumatic tire being capable of improving the performance on ice while improving the noise performance on dry road surfaces. In a tire with stud pins (P) implanted in a road contact surface of a tread portion (1), a pin shape of a tip portion (24) of the stud pin (P) is configured to be a shape having a longitudinal direction. With respect to a plurality of first stud pins (P1) in which an angle formed by the longitudinal direction of the pin shape and a tire width direction ranges from 0° to 10°, a plurality of second stud pins (P2) in which an angle formed by the longitudinal direction of the pin shape and the tire width direction is larger than the angle of the first stud pins (P1) are scattered in a tire circumferential direction.

Description

Title of Invention: PNEUMATIC TIRE

Technical Field

[0001]

The present invention relates to a tire in which stud pins are implanted in a road contact surface of a tread portion.

Background Art

[0002]

In areas with severe winters such as Northern Europe and Russia, studded tires are primarily used as winter tires. In a studded tire, a plurality of implanting holes for implanting stud pins are provided in a tread portion, and stud pins are implanted in these implanting holes (see Patent Document 1, for example). Since these stud pins have an effect of scratching icy and snowy road surfaces during travel on the icy and snowy road surfaces, the performance on ice can be improved. However, during travel on road surfaces other than icy and snowy road surfaces (in particular, dry paved road surfaces), hard stud pins hit the paved road surfaces to generate pin noises that may lead to a degradation in noise performance on dry road surfaces. In addition, even in areas with severe winters, there is often an opportunity for traveling on paved road surfaces (dry road surfaces) other than icy and snowy road surfaces.

Therefore, studded tires are required to improve noise performance on dry road surfaces while effectively delivering running performance (in particular, traction performance on ice) on icy and snowy road surfaces.

Citation List

N Patent Literature

N [0003]

O 30 Patent Document 1: JP 2018-187960 A

R

I Summary of Invention > Technical Problem = [0004] a 35 An object of the present invention is to provide a tire having stud pins

S implanted in a road contact surface of a tread portion, the tire being capable of improving the noise performance on dry road surfaces while improving the performance on ice.

Solution to Problem

[0005]

A tire according to an embodiment of the present invention that achieves the above-described object includes a tread portion extending in a tire circumferential direction and having an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on an inner side of the sidewall portions in a tire radial direction. In the tire in which a plurality of stud pins are implanted in a road contact surface of the tread portion, each of the stud pins includes a body portion that is inserted into an installation hole provided in the tread portion and a tip portion that protrudes from a surface of the tread portion. When the tip portion is viewed from an upper surface side of each of the stud pins, a pin shape formed by an upper surface of the tip portion is a shape having a longitudinal direction.

The plurality of stud pins include a plurality of first stud pins in which an angle formed by the longitudinal direction and a tire width direction ranges from 0° to 10°, and a plurality of second stud pins in which an angle formed by the longitudinal direction and the tire width direction is larger than that of the first stud pins. The plurality of second stud pins are scattered in the tire circumferential direction with respect to the plurality of first stud pins.

Advantageous Effects of Invention

[0006]

In an embodiment of the present invention, since the stud pins disposed with the longitudinal directions of the pin shapes oriented differently from each other are provided in a mixed manner as described above, it is possible to effectively suppress noises (pin noises) on dry road surfaces while ensuring

N excellent performance on ice by the stud pins. Specifically, since the first stud

N pin and the second stud pin are disposed with the longitudinal directions of the

O 30 pin shapes oriented at different angles from each other and cause pin noises at e different freguencies from each other, noises can be reduced by a freguency

I dispersion effect of the coexistence of the first stud pin and the second stud pin. - In addition, since the first stud pins and the second stud pins are provided in a = mixed manner, an edge effect can be exhibited in a plurality of directions, a 35 which is advantageous in improving the performance on ice.

S [0007]

In an embodiment of the present invention, when the road contact surface of the tread portion is egually divided into three regions in the tire width direction, one or more first stud pins and one or more second stud pins are preferably disposed in each of the three regions. Accordingly, both of the first stud pins and the second stud pins are dispersedly disposed in the tire width direction, and thus an effect of coexistence of the first stud pin and the second stud pin in an entire area in the tire width direction can be effectively ensured. This provides an advantage in effectively suppressing noises (pin noises) on dry road surfaces while ensuring excellent performance on ice.

[0008]

In an embodiment of the present invention, a separation distance along the tire circumferential direction between the second stud pins closest to each other in the tire circumferential direction is preferably within a range from 1.0% to 100.0% of a ground contact length. Accordingly, at least one second stud pin is disposed in a ground contact region, and thus the effect of suppressing noises (pin noises) on dry road surfaces can be reliably obtained.

[0009]

In an embodiment of the present invention, a region defined between a pair of tire meridians arranged with a spacing of 1/4 of the ground contact length of the tire on a tire equator line is defined as a band region, and a plurality of the band regions are arranged over the entire circumference of the tire while shifting an angle by one degree along the tire circumferential direction. Then, it is preferable that the number n of stud pins included in each of the band regions is 4.0% or less of the total number N of stud pins in the entire circumference of the tire in all of the plurality of band regions, the number n of stud pins included in the band region is 2.0% or more of the total number N in 2/3 or more of the plurality of band regions, and at least one of the second stud pins is provided in each of the band regions. Disposing the stud pins in this manner is advantageous in effectively suppressing noises (pin

N noises) on dry road surfaces while ensuring excellent performance on ice. In

N particular, since the ratio of the number n of the stud pins to the total number N

O 30 of the stud pins is limited to 4.0% or less in all the band regions, it is possible e to reduce an impact when the stud pins come into contact with a road surface

I and to suppress the generation of pin noises during travel on dry road surfaces. = In addition, the band regions in which the ratio of the number n of the stud pins = to the total number N of the stud pins is set to an appropriate range of 2.0% or a 35 more are sufficiently provided over the entire circumference of the tire to

S satisfactorily deliver the performance on ice. Further, since one or more second stud pins are provided in each of the band regions, the effect of coexistence of the first stud pin and the second stud pin can be effectively ensured.

[0010]

In an embodiment of the present invention, total 135 to 250 stud pins are preferably provided. Providing the appropriate number of the stud pins in this manner is advantageous in improving the noise performance on dry road surfaces while effectively delivering the performance on ice.

[0011]

In an embodiment of the present invention, it is preferable that at least one concentrated region in which the ratio of the number n of stud pins included in the band region is 3.0% or more of the total number N is provided in the plurality of band regions, and the number of the concentrated regions is 1/3 or less of the plurality of band regions. In this manner, by providing the concentrated regions including a large number of stud pins and having an excellent performance on ice, it is possible to further improve the performance on ice. On the other hand, since the number of the concentrated regions is limited to 1/3 or less of the number of the plurality of band regions, the noise performance on dry road surfaces can be satisfactorily ensured even when the concentrated regions are provided.

[0012]

Preferably, the tire according to an embodiment of the present invention is a tire having a designated rotation direction, and on an outer surface of the tread portion, a lug groove extending from a tread end on one side of a tire equator toward an inner side in the tire width direction and reaching the tire equator with an inclination in the tire rotation direction and a lug groove extending from a tread end on the other side of the tire equator toward an inner side in the tire width direction and reaching the tire equator with an inclination in the rotation direction are alternately arranged in the tire circumferential direction. By employing the tread pattern described above (a pattern based on

N so-called V-grooves), the stud pins are less likely to be arranged linearly in the

N tire circumferential direction, which is advantageous in suppressing pin noises.

O 30 [0013] e In an embodiment of the present invention, an average protrusion

I amount Px of the first stud pin or the second stud pin whichever has a smaller - installation number and an average protrusion amount Py of the first stud pin or = the second stud pin whichever has a larger installation number preferably a 35 satisfy a relationship of Px > Py. Further, the average protrusion amount Px and

S the average protrusion amount Py preferably satisfy a relationship of Px > 1.05 x Py. Accordingly, since freguencies of noises caused by the stud pins having the smaller installation number are increased, it is possible to prevent noises caused by the stud pins having the larger installation number from being amplified and to disperse specific pin noises.

[0014]

The tire according to an embodiment of the present invention is 5 preferably a pneumatic tire, but may be a non-pneumatic tire. In a case of a pneumatic tire, the interior thereof can be filled with any gas including air and inert gas such as nitrogen.

[0015]

In an embodiment of the present invention, "ground contact length" refers to a length of a ground contact region on the tire equator in the tire circumferential direction. The ground contact region is formed when a regular load is applied to the tire mounted on a regular rim, inflated to a regular internal pressure (in a case of a pneumatic tire), and placed vertically on a flat surface. "Ground contact edge" refers to end portions of the ground contact region in a tire axial direction. “Regular rim” refers to a rim defined by a standard for each tire according to a system of standards that includes standards with which tires comply, and is “standard rim” defined by Japan Automobile

Tyre Manufacturers Association (JATMA), “Design Rim” defined by The Tire and Rim Association, Inc. (TRA), or “Measuring Rim” defined by European

Tire and Rim Technical Organization (ETRTO), for example. In the system of standards including standards with which tires comply, "regular internal pressure” is air pressure defined by each of the standards for each tire and refers to "maximum air pressure" in the case of JATMA, the maximum value being listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD

INFLATION PRESSURES" in the case of TRA, or "INFLATION PRESSURE" in the case of ETRTO. However, "regular internal pressure" is 250 kPa in the case of tires for a passenger vehicle. "Regular load" is a load defined by a

N standard for each tire according to a system of standards that includes standards

N with which tires comply, and refers to a "maximum load capacity" in the case

O 30 of JATMA, the maximum value being listed in the table of "TIRE LOAD e LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA,

I or "LOAD CAPACITY" in the case of ETRTO. The "Regular load" is a load = corresponding to 70% of the loads described above in the case of tires for a = passenger vehicle. a 35

S Brief Description of Drawings

[0016]

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 illustrating a tread surface of the pneumatic tire according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view schematically illustrating an example of a stud pin implanted in a tread portion.

FIG. 4 is a schematic view illustrating a pin shape of a stud pin according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram schematically illustrating variations in the number of stud pins for each band region.

Description of Embodiments

[0017]

Configurations according to embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018]

As illustrated in FIG. 1, a pneumatic tire according to an embodiment of the present invention includes a tread portion 1, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed on an inner side of the sidewall portions 2 in the tire radial direction.

In FIG. 1, reference sign CL denotes a tire equator, and reference sign E denotes a ground contact edge. Although not illustrated in FIG. 1 as FIG. 1 isa meridian cross-sectional view, the tread portion 1, the sidewall portions 2, and the bead portions 3 each extend in a tire circumferential direction to form an annular shape. Thus, a toroidal basic structure of the pneumatic tire is configured. Although the description using FIG. 1 is basically based on the illustrated meridian cross-sectional shape, all of the tire components each

N extend in the tire circumferential direction and form the annular shape.

N [0019]

O 30 A carcass layer 4 is mounted between the left-right pair of bead portions e 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the

I tire radial direction, and is folded back around a bead core 5 disposed in each - of the bead portions 3 from a vehicle inner side to a vehicle outer side. = Additionally, a bead filler 6 is disposed on the periphery of the bead core 5, and a 35 the bead filler 6 is enveloped by a body portion and a folded back portion of

S the carcass layer 4. On the other hand, in the tread portion 1, a plurality of belt layers 7 (two layers in FIG. 1) are embedded on an outer circumferential side of the carcass layer 4. The belt layers 7 each include a plurality of reinforcing cords inclining with respect to the tire circumferential direction, and are disposed such that the reinforcing cords of the different layers intersect each other. In these belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set in a range of, for example, 10° or more and 40° or less. In addition, a belt reinforcing layer 8 is provided on the outer circumferential side of the belt layers 7. The belt reinforcing layer 8 includes organic fiber cords oriented in the tire circumferential direction. In the belt reinforcing layer 8, the angle of the organic fiber cords with respect to the tire circumferential direction is set, for example, to from 0° to 5°.

[0020]

The present invention relates to the arrangement of stud pins P in a tire having the stud pins P implanted in a road contact surface of the tread portion 1, and thus a basic structure (cross-section structure) of the tire, and structures of grooves and land portions formed on the surface of the tread portion 1 (tread pattern) are not particularly limited. That is, an embodiment of the present invention may be applied to a pneumatic tire having a general cross-section structure. However, the basic structure is not limited to the aforementioned structure.

[0021]

FIG. 2 illustrates a tread surface of an example of a pneumatic tire according to an embodiment of the present invention. In the example of FIG. 2, the tire has a tread pattern in which a plurality of land portions 13 are defined by a plurality of lug grooves 11 extending along a tire width direction and a plurality of circumferential grooves 12 extending along the tire circumferential direction. In the illustrated example, the lug groove 11 includes a first lug groove 11a extending with an inclination with respect to the tire width direction and having one end located on the tire equator CL and the other end extending

N beyond a ground contact edge E on one side in the tire width direction, and a

N second lug groove 11b extending with an inclination with respect to the tire

O 30 width direction and having one end located on the tire eguator CL and the other e end extending beyond a ground contact edge E on the other side in the tire

I width direction. The first lug groove 11a and the second lug groove 11b are = disposed in a manner such that the one end of the first lug groove 11a and the = one end of the second lug groove 11b are arranged alternately in the tire a 35 circumferential direction on the tire equator CL and the first lug groove 11a and

S the second lug groove 11b form a substantially V shape. In particular, in a case of a tire for which a rotation direction R is designated, the respective end portions of the first lug groove 11a and the second lug groove 11b on a side of the tire equator CL are preferably located on a side of the rotation direction R with respect to the end portions on a side of the ground contact edge E. With such a substantially V-shaped groove as a base, the stud pins P are less likely to be arranged linearly in the tire circumferential direction, which is advantageous in suppressing pin noises.

[0022]

The circumferential groove 12 extends with an inclination with respect to the tire circumferential direction so as to connect the lug grooves 11 adjacent to each other in the tire circumferential direction at an intermediate portion in a length direction of each lug groove 11. A center land portion 13a is defined on the inner side of the circumferential groove 12 in the tire width direction, and a shoulder land portion 13b (shoulder block) is defined on the outer side of the circumferential groove 12 in the tire width direction. Further, in the illustrated example, an auxiliary groove 14 is provided at an intermediate portion in a length direction of each of the circumferential grooves 12. The auxiliary groove 14 extends from the circumferential groove 12 toward a side of the tire equator

CL and has one end communicating with the circumferential groove 12 and the other end terminating in the center land portion 13a. Further, a plurality of sipes 14 are provided in each of the land portions 13. The stud pins P can be implanted in any land portion 13.

[0023]

The stud pins P are implanted in implanting holes for stud pins provided on the road contact surface of the tread portion 1. The stud pin P is implanted such that the stud pin P is inserted into the implanting hole that is in an expanded condition, and then the implanting hole is released from the expanded condition. FIG. 3 is a cross-sectional view schematically illustrating a state in which the stud pin P is implanted in the implanting hole of the tread portion 1.

N In the illustrated example, a double flange-type stud pin P is described as the

N stud pin P, but stud pins having other structures such as a single flange-type

S 30 stud pin may also be used. ® [0024]

I As illustrated in FIG. 3, the stud pin P includes a body portion 21 having - a cylindrical shape, a road contact surface side flange portion 22, a bottom side = flange portion 23, and a tip portion 24. The road contact surface side flange a 35 portion 22 and the bottom side flange portion 23 have a diameter greater than a

S diameter of the body portion 21, and the road contact surface side flange portion 22 is formed on a road contact surface side (outer side in the tire radial direction) of the body portion 21, and the bottom side flange portion 23 is formed on a bottom side (inner side in the tire radial direction) of the body portion 21. The tip portion 24 protrudes outward in the tire radial direction from the road contact surface side flange portion 22 in the pin axis (center of the stud pin P). Since the tip portion 24 protrudes from the road contact surface in a state where the stud pin P is implanted in the tread portion 1, the tip portion 24 can bite into icy and snowy road surfaces and deliver the traction characteristics on ice. The tip portion 24 is made of a material (for example, a tungsten compound) harder than other portions (the body portion 21, the road contact surface side flange portion 22, and the bottom side flange portion 23) made of, for example, aluminum or the like. In an embodiment of the present invention, the number of the stud pins P is defined in the following description.

When at least a part of the tip portion 24 of a stud pin P is present within a band region to be described later, the stud pin P is counted as being included in the band region.

[0025]

In an embodiment of the present invention, the shape of the tip portion 24 when viewed from an upper surface of the stud pin P as illustrated in FIG. 4 is referred to as a pin shape. The pin shape of the stud pin P (tip portion 24) according to an embodiment of the present invention is a shape having a longitudinal direction. The pin shape of the stud pin P (tip portion 24) according to an embodiment of the present invention is not particularly limited as long as the pin shape has a longitudinal direction. For example, the pin shape illustrated in FIG. 4A is an elliptical shape in which an extension direction of a major radius is a longitudinal direction. The pin shape illustrated in FIG. 4B is a rectangular shape in which an extension direction of a long side is a longitudinal direction. The pin shape illustrated in FIG. 4C is a shape formed by joining two hexagons via one side. Even a complicated shape such

N as the example of FIG. 4C corresponds to the pin shape having a longitudinal

N direction according to an embodiment of the present invention as long as such a

O 30 complicated shape can be generally recognized as a shape having a longitudinal e direction. In the example of FIG. 4C, the lateral direction of the drawing (an

I extension direction of the dashed line in the drawing) is a longitudinal = direction. = [0026] a 35 In an embodiment of the present invention, an angle formed by the

S longitudinal direction of the stud pin P (tip portion 24) and the tire width direction (hereinafter referred to as a "longitudinal direction angle") is not common to all the stud pins P, and a plurality of stud pins provided in the tread portion 1 include a plurality of first stud pins P1 having a longitudinal direction angle 61 of 0° to 10°, and a plurality of second stud pins P2 having a longitudinal direction angle 62 larger than the longitudinal direction angle 61 of the first stud pins P1. A group consisting of the plurality of first stud pins P1 and a group consisting of the plurality of second stud pins P2 are not separately provided in different regions of the tread surface, but the plurality of first stud pins P1 and the plurality of second stud pins P2 are provided in a mixed manner, and in particular, the plurality of second stud pins P2 are disposed so as to be scattered in the tire circumferential direction with respect to the plurality of first stud pins P1.

[0027]

Since the stud pins P (the first stud pins P1 and the second stud pins P2) disposed with the longitudinal directions of the pin shapes oriented differently from each other are provided in a mixed manner as described above, it is — possible to effectively suppress noises (pin noises) on dry road surfaces while ensuring excellent performance on ice by the stud pins P. That is, since the first stud pin P1 and the second stud pin P2 are disposed with the longitudinal directions of the pin shapes oriented at different angles from each other as described above and cause pin noises at different frequencies from each other, noises can be reduced by a frequency dispersion effect of the coexistence of the first stud pin P1 and the second stud pin P2. In addition, since the first stud pins P1 and the second stud pins P2 are provided in a mixed manner, an edge effect can be exhibited in a plurality of directions, which is advantageous in improving the performance on ice.

[0028]

The first stud pin P1 and the second stud pin P2 are distinguished by the longitudinal direction angles 01 and 02 as described above. Thus, the first stud

N pin P1 and the second stud pin P2 may be the stud pins P having an identical

N shape implanted with the orientation (longitudinal direction angle) of the tip

O 30 portion changed. Alternatively, the first stud pin P1 and the second stud pin P2 e may be a plurality of types of stud pins P having different shapes. z [0029] - As described above, the longitudinal direction angle 01 of the first stud = pin P1 ranges from 0° to 10°. On the other hand, the longitudinal direction a 35 angle 02 of the second stud pin P2 is not particularly limited as long as the

S longitudinal direction angle 02 is larger than the longitudinal angle 01 of the first stud pin P1, but preferably ranges from 30° to 90°, and more preferably from 45° to 85°. By setting the longitudinal direction angles of the first stud pin P1 and the second stud pin P2 in this manner, the effect of reducing noises and the effect of improving the performance on ice can be exhibited in a well- balanced manner.

[0030]

In an embodiment of the present invention, it is effective to provide the stud pins P having different longitudinal direction angles in a mixed manner.

Thus, in addition to the first stud pins P1 and the second stud pins P2, stud pins

P for which different longitudinal direction angles are set may also be provided.

In other words, the stud pins P classified as the second stud pins P2 may include a plurality of groups of stud pins P having different longitudinal direction angles as long as within the above-described angle range.

[0031]

As illustrated in FIG. 2, regardless of the tread pattern formed on the surface of the tread portion 1, a region defined between a pair of tire meridians arranged with a spacing of 1/4 of a ground contact length of the tire on the tire equator CL is defined as a band region A (see the hatched portions in FIG. 2, for example). Then, as schematically illustrated in FIG. 5, a plurality of band regions A (Al, A2, A3, ...) are arranged over the entire circumference of the tire while shifting an angle by one degree along the tire circumferential direction, and the number n of the stud pins P included in each of the band regions A (Al,

A2, A3, ...) is measured. Note that FIG. 5 schematically illustrates the arrangement of the band regions A, and details of the tread pattern formed in the tread portion 1 and the specific arrangement of the stud pins P are omitted.

The band regions A of A3 and subsequent reference signs are also omitted. A reference sign R in FIG. 5 denotes the tire circumferential direction (tire rotation direction).

[0032]

N In all of the plurality of band regions A defined as described above, the

N number n of the stud pins P included in each of the band regions A is set to

O 30 4.0% or less of the total number N of the stud pins P in the entire circumference e of the tire. In the example illustrated in FIG. 5, the number n of the stud pins P

I is seven or less. In the example of FIG. 5, the total number N is assumed to be - 190, then 4.0% of the total number N is 7.6, and thus the example of FIG. 5 = satisfies the above-described condition. Also in the example of FIG. 2, a 35 assuming that the total number N is 190, the number n of the stud pins P is

S seven or less in each of the three band regions A (hatched portions) surrounded by dot-dashed lines, which satisfies the above-described condition. On the other hand, in 2/3 or more of the plurality of band regions A, the number n of the stud pins P included in the band region A is set to 2.0% or more of the total number N of the stud pins P. For example, in a case where the total number N is 190, 2.0% of the total number N is 3.8, and thus, in the example of FIG. 5, the above-described condition is satisfied when the number of the band regions A in which four or more stud pins P are provided are 2/3 or more of the number of the plurality of band regions A. As described above, since the ratio of the number n of the stud pins P provided to the total number N of the stud pins P is limited to as low as 4.0% or less in all the band regions A, it is possible to suppress noises generated when the stud pins P come into contact with road surfaces during travel on dry road surfaces. In addition, since the band regions

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 are sufficiently provided over the entire circumference of the tire to satisfactorily deliver the performance on ice.

[0033]

The band region A preferably includes both of the first stud pin P1 and the second stud pin P2. In particular, in a case where the first stud pins P1 are mainly provided and the second stud pins P2 are mixed thereto, one or more second stud pins P2 are preferably provided in the band region A. Since stud pins (second stud pins P2) having longitudinal direction angles different from the longitudinal direction angles of other stud pins (first stud pins P1) are included in each of the plurality of band regions A as described above, the effect of reducing noises by mixing the second stud pins P2 can be reliably exhibited.

[0034]

When a band region A in which the number n of the stud pins P included in the band region A is 3.0% or more of the total number N of the stud pins P is

N distinguished as a concentrated region A' among the plurality of band regions

N A, it is preferable that one or more concentrated regions A' are provided on the

O 30 tire circumference. In the example illustrated in FIG. 5, the total number N is e assumed to be 190 as described above, and 3.0% of the total number N is 5.7.

I Thus, in the example of FIG. 5, the band regions A in which six or more stud = pins P are provided correspond to the concentrated regions A'. Meanwhile, = among the three band regions A (hatched portions) illustrated in FIG. 2, the a 35 bandregionsAin which the number n of the stud pins P is six or seven

S correspond to the concentrated regions A'. In FIG. 2, since the band region A in which the number n of the stud pins P is seven also corresponds to a closely- concentrated region A"' to be described later, the reference sign thereof is denoted as A (A"), but this band region A also corresponds to the concentrated region A'. When a plurality of the concentrated regions A' are provided, it is preferable that the number of the concentrated regions A' is limited to 1/3 or less of the number of the plurality of band regions A. Since the number n of the stud pins P is larger in the concentrated region A' than in other band regions A and thus the concentrated region A' excels in the performance on ice, the performance on ice can be further improved by providing the concentrated region A'. On the other hand, since the number of the concentrated regions A' is limited to 1/3 of the number of the plurality of band regions A, it is possible to satisfactorily deliver the noise performance on dry road surfaces even when the concentrated regions A' are provided. The number of the concentrated regions

A' exceeding 1/3 of the number of the plurality of band regions A means an increase in the concentrated regions A' in which many stud pins P that may cause a shock feeling during traveling are provided, which makes it difficult to satisfactorily deliver the noise performance.

[0035]

Further, when a band region A in which the number n of the stud pins P included in the band region A is 3.5% or more of the total number N of the stud pins P is distinguished as a closely-concentrated region A" among the concentrated regions A', it is preferable that one or more closely-concentrated regions A" are provided on the tire circumference. In the example illustrated in

FIG. 5, the total number N is assumed to be 190 as described above, and 3.5% of the total number N is 6.7. Thus, in the example of FIG. 5, the band regions A in which seven or more stud pins P are provided correspond to the closely- concentrated regions A". Meanwhile, among the three band regions A (hatched portions) illustrated in FIG. 2, the band region A in which the number n of the stud pins P is seven corresponds to the closely-concentrated region A". When a

N plurality of the closely-concentrated regions A" are provided, it is preferable

N that the spacing between the closely-concentrated regions A" adjacent to each

O 30 other in the tire circumferential direction is 100% or more of the ground e contact length of the tire. Since the closely-concentrated region A" is

I particularly excellent in the performance on ice among the concentrated regions = A', it 1s possible to further improve the performance on ice. On the other hand, = since the spacing between the closely-concentrated regions A" is set to be a 35 larger than the ground contact length of the tire, the number of the closely-

S concentrated regions A" present in the ground contact surface during rolling of the tire is one or less, and thus it is possible to satisfactorily deliver the noise performance on dry road surfaces even when the closely-concentrated regions

A" are provided. When the spacing between the closely-concentrated regions

A" is less than 100% of the ground contact length, a plurality of the closely- concentrated regions A" in which many stud pins P that may cause an increase in noises during traveling are present in the ground contact surface, which makes it difficult to satisfactorily deliver the noise performance. Note that the spacing between the closely-concentrated regions A" is a length along the tire circumferential direction between the tire meridians facing each other between the closely-concentrated regions A" adjacent to each other.

[0036]

The stud pins P may be arranged as described above, and the total number of the stud pins P in the entire tire is preferably from 135 to 250, and more preferably from 135 to 200. Providing the appropriate number of the stud pins P in the entire tire as described above is advantageous for satisfactorily delivering the noise performance while effectively delivering the performance on ice. When the total number of the stud pins P is less than 135, the traction performance on ice cannot be sufficiently improved. When the total number of the stud pins P exceeds 250, the noise performance cannot be sufficiently delivered.

[0037]

As illustrated in FIG. 2, among three regions obtained by equally dividing the road contact surface (an area between the ground contact edges E on both sides in the tire width direction) of the tread portion 1 in the tire width direction, a region located on the tire equator CL is defined as a center region

Ce, and each of a pair of regions located on both sides of the center region Ce in the tire width direction is defined as a shoulder region Sh. Then, in the band regions A in which the number n of the stud pins P is three or more, it is preferable that at least one stud pin P is provided in each of the center region

N Ce and the pair of shoulder regions Sh. By distributing and disposing the stud

N pins P in the tire width direction in this manner, a force of scratching icy and

O 30 snowy road surfaces can be efficiently obtained in the entire area in the tire e width direction, which is advantageous for improving the performance on ice.

I Further, the uniformity in the tire width direction can also be improved. For - example, when the total number N of the stud pins P is 135, in the band regions = A in which the number n of the stud pins P is 2.0% or more of the total number a 35 N, the number n of the stud pins P is three or more (135 x 0.020 = 2.7). In this

S case, when the above-described manner of distributing and disposing the stud pins P is employed, at least one stud pin P is distributed and disposed in each of the center region Ce and the pair of the shoulder regions Sh in 2/3 or more of the plurality of band regions A. Thus, this is extremely effective to improve the performance on ice.

[0038]

When the road contact surface (a region between the ground contact edges E on both sides in the tire width direction) of the tread portion 1 is equally divided into three regions in the tire width direction, one or more first stud pins P1 and one or more second stud pins P2 are preferably disposed in each of the three regions (the center region Ce and the pair of the shoulder regions Sh). Accordingly, both of the first stud pins P1 and the second stud pins

P2 are dispersedly disposed in the tire width direction, and thus the effect of coexistence of the first stud pin P1 and the second stud pin P2 in the entire area in the tire width direction can be effectively ensured. This provides an advantage in effectively suppressing noises (pin noises) on dry road surfaces while ensuring excellent performance on ice.

[0039]

In addition, one or more first stud pins P1 and one or more second stud pins P2 are preferably present in the ground contact region. For example, in a case where the first stud pins P1 constitute the majority and a small number of the second stud pins P2 are mixed relative to a large number of the first stud pins P1, one or more second stud pins P2 are preferably included in the ground contact region. In particular, a separation distance L along the tire circumferential direction between the second stud pins P2 closest to each other in the tire circumferential direction is preferably within a range from 1.0% to 100.0% of the ground contact length. Accordingly, at least one second stud pin

P2 is disposed in the ground contact region, and thus the effect of suppressing noises (pin noises) on dry road surfaces can be reliably obtained. When the separation distance L is less than 1.0% of the ground contact length, the second

N stud pins P2 are too close to each other, which may increase pin noises. When

N the separation distance L exceeds 100.0% of the ground contact length, no

O 30 second stud pin P2 is included in the ground contact region, and thus the effect e of coexistence of the first stud pin P1 and the second stud pin P2 is not

I sufficiently achieved. = [0040] = Protrusion amounts h of the stud pins P may be uniform. However, when a 35 the average value of the protrusion amounts h of the first stud pins P1 or the

S second stud pins P2 whichever has a smaller installation number is an average protrusion amount Px and when the average value of the protrusion amounts h of the first stud pins P1 or the second stud pins P2 whichever has a larger installation number is an average protrusion amount Py, Px and Py preferably satisfy a relationship of Px > Py, and more preferably satisfy a relationship of

Px > 1.05 x Py. By setting the protrusion amounts h of the stud pins P in this manner, frequencies of noises caused by the stud pins P having the smaller installation number are increased, and thus it is possible to prevent noises caused by the stud pins P having the larger installation number from being amplified and to disperse specific pin noises.

[0041]

An embodiment of the present invention will further be described below by way of Examples, but the scope of an embodiment of the present invention is not limited to Examples.

Examples

[0042]

Eighteen types of pneumatic tires, that is, pneumatic tires according to

Conventional Example 1, Comparative Examples 1 and 2, and Examples 1 to 15 are manufactured. The pneumatic tires have a tire size of 205/55R16 94T, a basic structure illustrated in FIG. 1, and a basic tread pattern illustrated in FIG. 2, and the pneumatic tires are configured as shown in Tables 1 and 2.

[0043]

In Tables 1 and 2, "Total number N" refers to the total number of the stud pins provided in the entire tire, and "n" refers to the number of the stud pins included in each band region. In the fields of "Presence of first stud pin" and "Presence of second stud pin", presence or absence in each region obtained by equally dividing the road contact surface of the tread portion into three regions is indicated as "presence or absence in the shoulder region on one side/presence or absence in the center region/presence or absence in the

N shoulder region on the other side". "Ratio of second stud pins to first stud pins"

N is the ratio (%) of the installation number of the second stud pins to the

O 30 installation number of the first stud pins provided in the tread portion. Note e that, in each of the examples shown in the tables in which the second stud pins

I are included, the installation number of the second stud pins is smaller than the - installation number of the first stud pins. In the field of "Average longitudinal = direction angle", an average value of angles formed by the longitudinal a 35 directions of the pin shapes with respect to the tire width direction is indicated

S for each of the first stud pin and the second stud pin. "Separation distance L between second stud pins" is a separation distance along the tire circumferential direction between the second stud pins closest to each other in the tire circumferential direction, and is indicated as a ratio (%) to the ground contact length.

[0044]

For "Maximum value of n in band region", the upper limit condition defined in an embodiment of the present invention (4.0% of the total number N = 0.04 N), a measured value in each tire, and a magnitude relationship between these values are indicated. In particular for the magnitude relationship, "Good" is indicated when the measured value is the upper limit condition (0.04 N) or less, and "Bad" is indicated when the measured value exceeds the upper limit condition (0.04 N). "Standard placement region" refers to the band regions in which the number n of the stud pins satisfies the condition of 2.0% or more of the total number N of the stud pins. For "Standard placement region", the lower limit condition defined in an embodiment of the present invention (2.0% of the total number N = 0.02 N), the presence of the standard placement region, and theratio of the standard placement regions to all the band regions are indicated.

For "Concentrated region", the lower limit condition defined in an embodiment of the present invention (3.0% of the total number N = 0.03 N), the presence of the concentrated region, and the ratio of the concentrated regions to all the band regions are indicated. In "Presence of second stud pin in band region", "Yes" is indicated when one or more second stud pins are included in each band region, and "No" is indicated when no second stud pin is included in each band region. "Px/Py" is aratio of the average protrusion amount Px of the first stud pin or the second stud pin whichever has a smaller installation number (the second stud pin in the example shown in the tables) to the average protrusion amount Py of the first stud pin or the second stud pin whichever has a larger installation number (the first stud pin in the example shown in the tables).

[0045]

N The above-described eighteen types of pneumatic tires (the pneumatic

N tires of Conventional Example 1, Comparative Examples 1 and 2, and

O 30 Examples 1 to 15) had a common ground contact length of 120 mm. That is, in e each example, the length of the band region in the tire circumferential direction

I (1/4 of the ground contact length of the tire) is 30 mm. = [0046] = These pneumatic tires were evaluated for braking performance on ice a 35 and noise performance on dry road surfaces in the following evaluation

S methods, and the results are shown in Tables 1 and 2.

[0047]

Braking Performance on Ice

Each test tire was mounted on an ETRTO standard rim (a rim size of 16 x 6.5J), inflated to a vehicle specified air pressure, and mounted on a front wheel drive vehicle having an engine displacement of 1.4 L. Then, on a test course (straight track) including icy and snowy road surfaces, a brake was applied at an initial speed of 25 km/h, and a braking distance until the speed was reduced from 20 km/h to 5 km/h was measured. Evaluation results were expressed by index values, using the reciprocals of measured values, with the value of Conventional Example 1 as 100. The larger this index value is the shorter the braking distance is, which means the braking performance on Ice is excellent. Note that, the index value of "98" or more indicates that good braking performance on ice at a similar level to Conventional Example 1 was obtained.

[0048]

Noise Performance on Dry Road Surfaces

Each test tire was mounted on an ETRTO standard rim (a rim size of 16 x 6.5J), inflated to an air pressure of 250 kPa, and mounted on a front wheel drive vehicle having an engine displacement of 1.4 L. Then, on a test course (asphalt road) including dry road surfaces, sensory evaluation on pin noises was performed by a test driver. Evaluation results are expressed as index values with Conventional Example 1 being assigned the index value of 100. The larger the index value is, the smaller the pin noises are, which means that the noise performance on dry road surfaces is excellent.

[0049]

N

O

N

I a a

LO

N

LO

N

O

N

[Table 1]

Table 1

Example 1 Example 1 | Example 2 1 2 3 4 5 6

Presence of first stud pin Yes/Yes/Yes | Yes/Yes/Yes

No Yes Yes Yes Yes Yes Yes

Presence of second stud pin No/No/No | No/No/No

Yes Yes Yes Yes Yes Yes Yes

Ratio of second stud pins to first % — | — | 65 | 20 | 35 | 35 | 35 | 35 | 35 stud pins e First etud nin oj 5 | 5 | 15 | 5 | 5 | 5 | 5 | 5 | 5

Average jiirst stud pin | 5 | 5 | 15 | 5 | 5 | 5 | 5 | 5 | 5

A }\P - rrr 1 tudinal longitudinal direction ISecond stud pin °l — | — | 45 I 45 | 45 I 45 | 45 | 45 | 45

N | F

N

O angle

N

! Separation distance L between I | | I I I I I I I

O o/l H | H | NE | ZA | QA | 194 | 07 | 07 | 07

O , N /0| | | LJ | JAT | oO | 140 | oO | oD | oD n second stud pins

N I 0. [Upper limit

I Maximum | ooo pieces 7.6 | 10 | 7.6 | 7.6 | 7.6 | 76 | 7.6 | 76 | 76 a lecondition (0.04 N) siä |2.—:—.:—1|1——:—1——=;ö———!———|——|——| —|—————— alue of nin [— — — 1 - | - | - "an i ao A - 2 IMeasured value pieces! 5 | 7 | 5 | 5 | 5 | 5 | 5 | 5 | 7 ster | —"1.—1|—.—1|—1|——1|—.|——+.| —.| | —

LO band region. <s---s---r-"--—-—-.-.|---!,/.ms",-"r",-t!—

S Standard ILower limit

N | mieracl 2 Q | < | 2 Q | 2 Q | 20 | 20 | 22 | 22 | 20 I 4.0. L L pitt D.0 | J | 2.0 | D.0 | 2.0 | 2.0 | 2.0 | D.0 | 2.0

P lacement lcondition (0.02 N) 22.1 12—.—.—1.11—.—.:—.1.:1——:—.1—-—-!—1|——1|—:—+—— . I. | <, | <, | <, | <, | <> | < | < | < | < [region [Presence | Yes | Yes | Yes | Yes | Yes | Yes I Yes | Yes | Yes sr 0000000000000 0-0 0 or - { - r ~~ 1 | —

Ratio % 50 50 50 50 50 50 50 70 70

Lower limit

NU pieces 5.7 7.5 5.7 5.7 5.7 5.7 5.7 5.7 5.7

Concentrated [condition (0.03 N)

Ratio moo [| o [o J oJofof olo] s.

Presence of second stud pin in band , No No No No No No No Yes Yes region , , Index

Braking performance on ice , 100 125 95 100 98 100 105 110 115 vag oise performance on dry road — Index| N | — | N k dd A A A A 100 | 3D | 105 | 105 | 110 | 107 | 112 | 115 | 112 surfaces value]

N [0050]

N

O

N

O

I

0

N

I a a

LO

N

LO

N

O

N

[Table 2]

Table 2

Example[Example[Example[ExampleExampleExample[ExampleExampleExample 7 8 9 10 11 12 13 14 15

Total number N pieces] 190 | 190 | 190 | 190 | 190 | 190 | 190 | 135 | 250 , . Yes/Yes/|Yes/Yes/|Yes/Yes/|Yes/Yes/|Yes/Yes/|Yes/Yes/|Yes/Yes/|Yes/ Yes/|Yes/Yes/

Presence of first stud pin

Presence of second stud pin

Yes Yes Yes Yes Yes Yes Yes Yes Yes

Ratio of second stud pins to first stud k kd n a e fo or 1 e . % 35 1 45 | 60 I 35 | 35 | 35 I 35 | 35 | 35 pins Kk 1 11 i 11 i o

Average [First stud pin | s | s {| 5 | 0 | 10 | 5 | 5 | 5 | 5 . =—111313.1—.1—lo—1€->v>P 1 longitudinal . . [Second stud pin 1 45 | 45 | 45 | 45 | 45 | 45 | 45 | 45 | 45 direction angle | -

AN E

S Separation distance L between second

N o/| 07 | 07 | Qn | Qn | Qn | 1 | 1TNN | 07 | Qn , . 70 oJ | oJ | oJ | oJ | oJ | 19 | 1UU | oJ | oJ & stud pins ! [Upper limit condition I I I I | | I | | I

M 1 K at, | FF nl mal n £ | n £ | n £ | n £ | n £ | n £ | n £ | < A | 16

N aximum value | =. pieces] 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 2.4 | 19 (0.04 N)

Raa pp |...

Ek of n in band 1 o Measured value pieces! 7 I 7 I 7 I 7 | 7 | 7 I 7 | 5 | 10 : pve tt ve verve peels 111 TV region 0 © © — AA 2 IMagnitude relationship I Good I Good I Good I Good I Good I Good I Good I Good I Good I

LO - — —

LO [Lower limit condition I I I I | | I | | I

N | manad 2 Q | 2 Q | 2 Q | 2 Q | 2 Q | 2 Q | 7 Q | n 7 | <

Ql , |, oo PICECC5I 2.0 | 2.0 | 2.0 | 2.0 | 2.0 | 2.0 | 2.0 | L.I | I

O Standard (0.02 N) tt

N oo 1 1 1 l l = 1 l = placement region|Presence I Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes pet PP fp PP 1 BES 21 <

L. 1 n L 1 —- 1 L A - 1 Li NÄ LÄ L | L]

I IRatio %l 70 | 70 1 70 1 70 | 70 | 70 1 70 | 70 | 70

L ENÄÄ] | rE

Lower limit condition . pieces| 5.7 5.7 5.7 5.7 5.7 5.7 5.7 4.1 7.5

Concentrated (0.03 N)

Presence of second stud pin in band region . . Index

Braking performance on ice 117 110 100 120 115 117 117 105 135 value oise performance on dry road Index 115 125 130 115 115 113 115 120 105 surfaces Vaud

N

O

N

I a a

LO

MN

LO

N

O

N

[0051]

As can be seen from Table 1, Examples 1 to 15 satisfactorily delivered the braking performance on ice and provided improved noise performance in a highly compatible manner, as compared to the Conventional Example 1. On the other hand, Comparative Example 1 presented degraded noise performance because no second stud pin was mixed in with the first stud pins. Comparative

Example 2 presented degraded braking performance on ice because the longitudinal direction angle of the first stud pin was too large.

Reference Signs List

[0052] 1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt reinforcing layer 11 Lug groove 12 Circumferential groove 13 Land portion 14 Auxiliary groove 15 Sipe

P Stud pin

P1 First stud pin

P2 Second stud pin

N A Band region

N A' Concentrated region

O 30 A" Closely-concentrated region e Ce Center region

I Sh Shoulder region > CL Tire equator = E Ground contact edge a 35

N

Claims

Claims

[Claim 1] A tire comprising: a tread portion extending in a tire circumferential direction and having an annular shape; a pair of sidewall portions disposed on both sides of the tread portion; and a pair of bead portions disposed on an inner side of the sidewall portions in a tire radial direction, in the tire with a plurality of stud pins implanted in a road contact surface of the tread portion, each of the stud pins comprising a body portion to be inserted into an installation hole provided in the tread portion and a tip portion protruding from a surface of the tread portion, when viewed from an upper surface side of each of the stud pins, a pin shape formed by an upper surface of the tip portion being a shape having a longitudinal direction, the plurality of stud pins comprising, a plurality of first stud pins having an angle formed by the longitudinal direction and a tire width direction, the angle ranging from 0° to 10°, and a plurality of second stud pins having an angle formed by the longitudinal direction and the tire width direction, the angle being larger than the angle of the first stud pins, and the plurality of second stud pins being scattered in the tire circumferential direction with respect to the plurality of first stud pins. N N [Claim 2] O The tire according to claim 1, wherein, when the road contact surface of e the tread portion is egually divided into three regions in the tire width I direction, one or more of the first stud pins and one or more of the second stud - pins are disposed in each of the three regions. S a [Claim 3] S The tire according to claim 1 or 2, wherein a separation distance along the tire circumferential direction between the second stud pins closest to each other in the tire circumferential direction is within a range from 1.0% to

100.0% of a ground contact length.

[Claim 4] The tire according to any one of claims 1 to 3, wherein a region defined between a pair of tire meridians arranged with a spacing of 1/4 of a ground contact length of the tire on a tire equator line is defined as a band region, a plurality of the band regions are arranged over an entire circumference of the tire while shifting an angle by one degree along the tire circumferential direction, in all of the plurality of band regions, a number n of the stud pins included in each of the band regions is 4.0% or less of a total number N of the stud pins in the entire circumference of the tire, in 2/3 or more of the plurality of band regions, a number n of the stud pins included in each of the band regions is 2.0% or more of the total number N, and at least one of the second stud pins is provided in each of the band regions.

[Claim 5] The tire according to claims 1 to 4, wherein a total number of the stud pins ranges from 135 to 250.

[Claim 6] The tire according to any one of claims 1 to 5, wherein, in the plurality of band regions, N one or more concentrated regions in which the number n of the stud pins N included in the band region is 3.0% or more of the total number N are present, O and e a number of the concentrated regions is 1/3 or less of the plurality of I band regions. a = [Claim 7] a The tire according to any one of claims 1 to 6, wherein S a rotation direction is designated for the tire, and on an outer surface of the tread portion, a lug groove extending from a tread end on one side of a tire eguator toward an inner side in the tire width direction and reaching the tire equator with an inclination in the rotation direction and a lug groove extending from a tread end on an other side of the tire equator toward an inner side in the tire width direction and reaching the tire equator with an inclination in the rotation direction are alternately arranged in the tire circumferential direction.

[Claim 8] The tire according to any one of claims 1 to 7, wherein an average protrusion amount Px of the first stud pins or the second stud pins whichever has a smaller installation number and an average protrusion amount Py of the first stud pins or the second stud pins whichever has a larger installation number satisfy a relationship of Px > Py.

[Claim 9] The tire according to claim 8, wherein the average protrusion amount Px and the average protrusion amount Py satisfy a relationship of Px > 1.05 x Py. N N O N © <Q 0 N I a a LO N LO LO N N O N