FI20225419A1

FI20225419A1 - Pneumatic tire

Info

Publication number: FI20225419A1
Application number: FI20225419A
Authority: FI
Inventors: Takashi Shibai
Original assignee: Yokohama Rubber Co Ltd
Priority date: 2019-11-01
Filing date: 2020-09-29
Publication date: 2022-05-13
Also published as: CN114599531A; CN114599531B; WO2021085004A1; FI130328B; JP2021070449A; JP7172953B2

Abstract

Provided is a pneumatic tire having stud pins implanted in a road contact surface of a tread portion, the pneumatic tire being capable of reducing damage to road surfaces while improving performance on ice. In the pneumatic tire with stud pins (P) implanted in a road contact surface of a tread portion (1), a region defined between a pair of tire meridians arranged with an interval of 0.8260 of a tire circumferential length on a tire equator (CL) is defined as a band region (A), and a plurality of band regions (A) are arranged over the entire circumference of the tire while shifting an angle by one degree along the tire circumferential direction. Then, the plurality of band regions includes concentrated regions (A') in which the number of the stud pins is four or more and scattered regions (a) in which the number of the stud pins is three or less. A plurality of the concentrated regions (A') is intermittently provided among the plurality of band regions (A) along the tire circumferential direction.

Description

TITLE OF THE INVENTION: PNEUMATIC TIRE Technical Field

[0001] The present invention relates to a pneumatic 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). Such stud pins may improve the running performance on icy and snowy road surfaces, but may cause damage to road surfaces during traveling on road surfaces (common paved road surfaces) other than icy and snowy road surfaces. In addition, even in areas with severe winters, there is often an opportunity for traveling on paved road surfaces other than icy and snowy road surfaces. Therefore, studded tires are reguired to reduce damage to road surfaces while effectively delivering running performance (in particular, traction performance on 1ce) on icy and snowy road surfaces.

Citation List

Patent Literature

[0003] Patent Document 1: JP 2018-187960 A

Summary of Invention Technical Problem

[0004] An object of the present invention is to provide a pneumatic tire having stud pins implanted in a road contact surface of a tread portion, the

N pneumatic tire being capable of reducing damage to road surfaces while

N 30 improving the performance on ice. 3 en Solution to Problem > [0005] To achieve the object described above, a pneumatic tire according i to an embodiment of the present invention includes a tread portion extending in

D 35 atire circumferential direction and having an annular shape, a pair of sidewall > portions respectively disposed on both sides of the tread portion, and a pair of

N bead portions each disposed on an inner side of the pair of sidewall portions in

N a tire radial direction. In the pneumatic tire including stud pins implanted in a road contact surface of the tread portion, a region defined between a pair of tire meridians arranged with an interval of 0.8% of a tire circumferential length on a tire equator line is defined as a band region, and a plurality of band regions are arranged over the entire circumference of the pneumatic tire while shifting an angle by one degree along the tire circumferential direction. The plurality of band regions includes concentrated regions each of which has four or more stud pins in the band region and scattered regions each of which has three or less stud pins in the band region. A plurality of the concentrated regions are intermittently provided in the plurality of band regions along the tire circumferential direction.

Advantageous Effects of Invention

[0006] In an embodiment of the present invention, by providing the stud pins as described above, it is possible to reduce damage to road surfaces while effectively improving the performance on ice. Specifically, the concentrated region has a larger number of the stud pins, so the traction performance on ice can be improved, and the scattered region has a smaller number of the stud pins, so damage to road surfaces can be reduced. Further, the concentrated regions and the scattered regions are provided in a mixed manner in the tire circumferential direction, and the concentrated regions are intermittently present, so that damage to road surfaces can be effectively reduced without impairing the traction performance on ice.

[0007] In an embodiment of the present invention, in total 135 to 250 stud pins are preferably provided. Providing the appropriate number of the stud pins in this manner is advantageous for reducing damage to road surfaces while effectively delivering the traction performance on ice.

N

N [0008] In an embodiment of the present invention, an interval between ro 30 the concentrated regions adjacent to each other in the tire circumferential e direction is preferably 1.0% to 30.0% of the tire circumferential length. In this

I way, in intermittently providing the concentrated regions, the concentrated - regions can be provided on the tire circumference at an appropriate intervals, 2 which is advantageous for reducing damage to road surfaces while effectively a 35 delivering the traction performance on ice.

N

[0009] In an embodiment of the present invention, it is preferable that three to seven closely-concentrated regions having five or more stud pins are provided in the plurality of concentrated regions. Since the closely- concentrated region has the particularly high traction performance on ice among the concentrated regions, the traction performance on ice can be further improved. On the other hand, since the number of the closely-concentrated regions is limited to three to seven, it is possible to sufficiently reduce damage to road surfaces even when the closely-concentrated regions are provided.

[0010] An interval between the closely-concentrated regions adjacent to each other in the tire circumferential direction is preferably 5.0% to 60.0% of the tire circumferential length. In this way, the closely-concentrated regions can be provided on the tire circumference at appropriate intervals, which is advantageous for reducing damage to road surfaces while effectively delivering the traction performance on ice.

[0011] In an embodiment of the present invention, it is preferable that the average protruding amount Px of the stud pins included in the concentrated regions and the average protruding amount Pav of the stud pins included in the scattered regions satisfy the relationship of Px <0.9 x Pav. By setting the protruding amount of the stud pins in this manner, the protruding amount of the stud pins can be kept low in the concentrated region with the relatively large number of the stud pins, which is advantageous for reducing damage to road surfaces. In addition, ride comfort can also be improved.

[0012] In an embodiment of the present invention, “ground contact edge” refers to end portions of a ground contact region in a tire axial 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, and placed

N vertically on a flat surface. “Regular rim” refers to a rim defined by a standard

N for each tire according to a system of standards that includes standards with ro 30 which tires comply, and is “standard rim” defined by Japan Automobile Tyre e Manufacturers Association (JATMA), “Design Rim” defined by The Tire and

I Rim Association, Inc. (TRA), or “Measuring Rim” defined by European Tire = and Rim Technical Organization (ETRTO), for example. In the system of 2 standards including standards with which tires comply, "regular internal a 35 pressure" is air pressure defined by each of the standards for each tire and

S 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 standard for each tire according to a system of standards that includes standards with which tires comply, and refers to a "maximum load capacity" in the case of JATMA, the maximum value being listed in the table of "TIRE LOAD

LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, or "LOAD CAPACITY" in the case of ETRTO. The "Regular load" is a load corresponding to 80% of the loads described above in the case of tires for a passenger vehicle.

Brief Description of Drawings

[0013] 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 an explanatory diagram schematically illustrating variations in the number of stud pins for each band region.

Description of Embodiments

[0014] Configurations of embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0015] As illustrated in FIG. 1, a pneumatic tire of 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

N disposed in the sidewall portions 2 at an inner side in a tire radial direction. In

N FIG. 1, reference sign CL denotes a tire eguator, and reference sign E denotes a ro 30 ground contact edge. Note that FIG. 1 is a meridian cross-sectional view, and e although not illustrated, the tread portion 1, the sidewall portions 2, and the

I bead portions 3 each extend in the tire circumferential direction and each have - an annular shape, whereby a basic structure of a toroidal shape of the 2 pneumatic tire is formed. Although the description using FIG. 1 is basically a 35 based on the illustrated meridian cross-sectional shape, all of the tire

S components each extend in the tire circumferential direction and form the annular shape.

[0016] A carcass layer 4 is mounted between the left-right pair of bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the 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 5 outer side. Additionally, a bead filler 6 is disposed on the periphery of the bead core 5, and the bead filler 6 is enveloped by a body portion and a folded back portion of 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°.

[0017] An embodiment of the present invention may be applied to such a pneumatic tire having a general cross-sectional structure. However, the basic structure is not limited to the aforementioned structure. In addition, an embodiment of the present invention relates to the arrangement of stud pins P in a pneumatic tire having the stud pins P implanted in a road contact surface of the tread portion 1, and thus the structure (tread pattern) of grooves and land portions formed on the surface of the tread portion 1 is not particularly limited.

N

N [0018] Meanwhile, the pneumatic tire illustrated in FIG. 2 has a tread ro 30 pattern in which a plurality of land portions 13 are defined by a plurality of lug e grooves 11 extending along a tire width direction and a plurality of

I circumferential grooves 12 extending along the tire circumferential direction. - In the illustrated example, the lug groove 11 includes a first lug groove 11a 2 extending with an inclination with respect to the tire width direction and having a 35 oneend located on the tire eguator CL and the other end extending beyond a

S ground contact edge E on one side in the tire width direction, and a second lug groove 11b extending with an inclination with respect to the tire width direction and having one end located on the tire eguator CL and the other end extending beyond a ground contact edge E on the other side in the tire 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 circumferential direction on the tire equator CL and the first lug groove 11a and the second lug groove 11b form a substantially V shape. 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.

[0019] 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 pins P is implanted by inserting the stud pins into the implanting holes when the implanting holes are in an expanded condition, and then releasing the expansion of the implanting holes. FIG. 3 is a cross-sectional view schematically illustrating a state in which the stud pin P is implanted in the

N implanting hole of the tread portion 1. In the illustrated example, a double

N flange-type stud pin P is described as the stud pin P, but stud pins having other 3 30 structures such as a single flange-type stud pin may also be used. ©

I [0020] As illustrated in FIG. 3, the stud pin P includes a body portion P1 - having a cylindrical shape, a road contact surface-side flange portion P2, a 2 bottom-side flange portion P3, and a tip portion P4. The road contact surface- a 35 side flange portion P2 and the bottom-side flange portion P3 have a diameter

S greater than that of the body portion P1, and the road contact surface-side flange portion P2 is formed on a road contact surface side (outer side in the tire radial direction) of the body portion P1, and the bottom-side flange portion P3 is formed on a bottom side (inner side in the tire radial direction) of the body portion P1. The tip portion P4 protrudes outward in the tire radial direction from the road contact surface-side flange portion P2 in the pin axis (center of the stud pin P). Since the tip portion P4 protrudes from the road contact surface in a state where the stud pin P is implanted in the tread portion 1, the tip portion P4 can bite into icy and snowy road surfaces and deliver the traction characteristics on ice. The tip portion P4 is made of a material (for example, a tungsten compound) harder than other portions (the body portion P1, the road contact surface-side flange portion P2, and the bottom-side flange portion P3) made of, for example, aluminum or the like. In an embodiment of the present invention, the number of the stud pins P included in the band regions to be described later is defined. When at least a part of the tip portion P4 of a stud pin P is provided in a band region to be described later, the stud pin P is counted as being included in the band region.

[0021] In an embodiment of the present invention, 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 an interval of 0.8% of a tire circumferential length on a 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. 4, 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 of the stud pins P included in each of the band regions A (Al, A2, A3, ...) is measured. Note that FIG. 4 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

N signs are also omitted. The reference sign R in FIG. 4 denotes the tire

N circumferential direction. ro 30 e [0022] In an embodiment of the present invention, among the band

I regions A stated as above, when a region including four or more stud pins in the = band region A is defined as a concentrated region A', and a region having three 2 or less stud pins in the band region A is defined as a scattered region a, the a 35 concentrated regions A' and the scattered regions a are provided in a mixed

S manner in the tire circumferential direction. In other words, the plurality of concentrated regions A' are intermittently provided among the plurality of band regions A in the tire circumferential direction. The concentrated region A'

including a large number of the stud pins P can improve the traction performance on ice. The scattered region a including a small number of the stud pins P can reduce damage to road surfaces. Consequently, since the concentrated regions A' and the scattered regions a are provided in a mixed manner in the tire circumferential direction, and the concentrated regions A' are intermittently provided, damage to road surfaces can be effectively reduced without impairing the traction performance on ice.

[0023] Further, when a region having five or more stud pins is distinguished as a closely-concentrated region A” among the plurality of concentrated regions A’, it is preferable that three to seven closely-concentrated regions A” are provided. Since the closely-concentrated region A” has the particularly high traction performance on ice among the concentrated regions

A', the traction performance on ice can be further improved. On the other hand, since the number of the closely-concentrated regions A” is limited to three to seven, it is possible to sufficiently reduce damage to road surfaces even when the closely-concentrated regions A” are provided. When the number of the closely-concentrated regions A” is less than three, the effect of improving the traction performance on ice becomes insufficient. When the number of the closely-concentrated regions A” exceeds seven, damage to road surfaces cannot be sufficiently reduced.

[0024] As illustrated in the example of FIG. 2, when three rows of land portions including the center land portion 13a and a pair of shoulder land portions 13b are provided in the tread portion 1, it is preferable that at least one stud pin is provided in each land portion in the concentrated region A' in which four or more stud pins are provided and in the closely-concentrated region A”

N in which five or more stud pins are provided. Similarly, when, for example, five

N rows of land portions (a center land portion, a pair of shoulder land portions, re 30 and middle land portions defined between the center land portion and each of e the shoulder land portions) are provided in the tread portion 1, at least one stud

I pin is preferably provided in each land portion in the closely-concentrated - region A” in which five or more stud pins are provided. = a 35 [0025] The stud pins P may be arranged as described above, and the total

S number of the stud pins 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 in this manner is advantageous for reducing damage to road surfaces while effectively delivering the traction performance on ice.

When the total number of the stud pins is less than 135, the traction performance on ice cannot be sufficiently improved. When the total number of the stud pins exceeds 250, damage to road surfaces cannot be sufficiently reduced.

[0026] When the concentrated regions A' are intermittently arranged as described above, an interval L1 between the concentrated regions A' adjacent to each other in the tire circumferential direction is preferably 1.0% to 30.0% of the tire circumferential length. With the arrangement described above, the concentrated regions A' can be provided on the tire circumference at appropriate intervals, which is advantageous for reducing damage to road surfaces while effectively delivering the traction performance on ice. When the interval L1 between the concentrated regions A' adjacent to each other in the tire circumferential direction is less than 1.0% of the tire circumferential length, the concentrated regions A' are arranged closer to each other in the tire circumferential direction, and thus damage to road surfaces cannot be sufficiently reduced. When the interval L1 between the concentrated regions A' adjacent to each other in the tire circumferential direction exceeds 30.0% of the tire circumferential length, the concentrated region A' may not be sufficiently present in the ground contact surface, and this makes it difficult to sufficiently ensure the traction performance on ice. As illustrated in FIG. 2, the interval LI between the concentrated regions A' is a length along the tire circumferential direction between the tire meridians facing each other between the concentrated regions A' adjacent to each other. In FIG. 2, since the closely-concentrated region A” also corresponds to the concentrated region A', a distance between the closely-concentrated region A” and the concentrated region A' is indicated

N as the interval L1 between the concentrated regions A'. & ro 30 [0027] Further, an interval L2 between the closely-concentrated regions e A” adjacent to each other in the tire circumferential direction is preferably

I 5.0% to 60.0% of the tire circumferential length. Consequently, the closely- = concentrated regions A” can be provided on the tire circumference at an 2 appropriate intervals, which is advantageous for reducing damage to road a 35 surfaces while effectively delivering the traction performance on ice. When the

S interval L2 between the closely-concentrated regions A” adjacent to each other in the tire circumferential direction is less than 5.0% of the tire circumferential length, the closely-concentrated regions A” are arranged close to each other in the tire circumferential direction, and thus damage to road surfaces cannot be sufficiently reduced. When the interval L2 between the closely-concentrated regions A” adjacent to each other in the tire circumferential direction exceeds 60.0% of the tire circumferential length, the closely-concentrated region A” may not be sufficiently present in the ground contact surface, and this makes it difficult to sufficiently ensure the traction performance on ice. Note that, similar to the interval L1 between the concentrated regions A' described above, the interval L2 (not illustrated) 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.

[0028] The protruding amount h of the stud pins may be uniform.

However, when the average value of the protruding amounts h of the stud pins included in the concentrated regions A' is defined as an average protruding amount Px, and the average value of the protruding amounts h of the stud pins included in the scattered regions a is defined as an average protruding amount

Pav, it is preferable that the relationship of Px < 0.9 x Pav is satisfied. By setting the protruding amount h of the stud pins in this manner, the protruding amount of the stud pins can be kept low in the concentrated region A' with the relatively large number of the stud pins, which is advantageous for reducing damage to road surfaces. In addition, ride comfort can also be improved.

Furthermore, from the viewpoint of ensuring sufficient traction performance on ice, it is preferable to satisfy the relationship of Px > 0.7 x Pav.

[0029] Examples of the present invention will further be described below by way of Examples, but the scope of an embodiment of the present invention

N is not limited to Examples. & ro 30 Example e [0030] Eleven types of pneumatic tires, that is, pneumatic tires according

I to Conventional Example 1, Comparative Examples 1 and 2, and Examples 1 to - 8 are manufactured. The pneumatic tires have a tire size of 205/55R16 94T, a 2 basic structure illustrated in FIG. 1, and a basic tread pattern illustrated in FIG. a 35 2. The pneumatic tires are configured as indicated in Table 1 regarding the

S maximum number of the stud pins included in the closely-concentrated regions, the number of the concentrated regions, the number of the closely-concentrated regions, the total number of the stud pins, the interval (the minimum and the maximum values) between the concentrated regions adjacent to each other in the tire circumferential direction, the interval (the minimum and the maximum values) between the closely-concentrated regions adjacent to each other in the tire circumferential direction, the ratio Px/Pav that is the ratio of the average protruding amount Px of the stud pins included in the concentrated regions to the average protruding amount Pav of the stud pins included in the scattered regions.

[0031] Since the tire circumferential length of the pneumatic tire having the above-described size is 1980 mm, the length of each of the band regions in the tire circumferential direction (0.8% of the tire circumferential length) is 15.8 mm.

[0032] These pneumatic tires were evaluated for a steering stability on ice, braking performance on ice, and road surface damage reduction performance in the following evaluation methods, and the results are shown in

Table 1.

[0033] Steering Stability on Ice

Each test tire was mounted on a wheel having 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, and sensory evaluation on the steering stability performance was performed by a test driver on a test course (turning field) including icy and snowy road surfaces. Evaluation results are expressed as index values with Conventional Example 1 being assigned the index value of 100. This means that the larger the index value is, the higher the steering stability on ice is.

N

N [0034] Braking Performance on Ice re 30 Each test tire was mounted on a wheel having a rim size of 16 x 6.5], e inflated to a vehicle specified air pressure, and mounted on a front wheel drive

I 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 2 speed of 25 km/h, and a braking distance was measure until the speed was a 35 reduced from 20 km/h to 5 km/h. Evaluation results were expressed by index

S 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.

[0035] Road Surface Damage Reduction Performance

Each test tire was mounted on a wheel having a rim size of 16 x 6.5], 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, a test run was performed 200 times at a speed of 100 km/h on granite placed on a road surface, and a road surface wear amount was measured by measuring a wear amount based on a difference in the weight of the granite before and after the test run.

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 ism the smaller the road surface wear amount is, which means that road surface damage reduction performance is excellent. If the index value is "85" or more, it means that good road surface damage reduction performance is obtained.

N

O

N

LÖ

<Q ™

I a a o +

LO

N

O

N

O

— = ol = © ss?” + N D o N z * | ” slag

HO — — —

O

—

Er elä = Z| 2 ! < !

S al DN A n * Do 0 | = m S (SV =e 8

O

— = m| Le a sv n + — De R 0 2 S JN ol = | 2 | 2

H —_— — — — —

O a o \O gn wv wv wv OA © on © 2 "| ? S 7 x SI FF) ET) »

HO N ll — = 0

O

— a o — ~~ —

E + n n || < A =

S — — N — e oll 0 AN

N= S mM A — || — —

O

— a o N en AN

E m n m | e IS] «x e I, o

A | S o S < jo = | E| «n

H n ~~ — = =

O

— = o| NM >

EAN + + D + o x A SI a = n mM —_— — — — ON

O

— = ol = ©

O

> AN 2

SS o

SE ~~ — — = 5 S

S n

Om OI a en

O —_— — — —

O

> =

SS oS

SE wn — — = - n

O [1] el = =

O —_— — — — —

S - ge

Ee S

N o gf © SL

N > G

O S (i S| EE

N O = = — b 3 a = | = | = | = x 212 217 2

O O O oll! koll! koll

O O < S < n a [e — = 2 oc = a 1 1 = o ho] . — =) O = a s |2 a S S 21 21,8 o Sä S n! n n ön 6 e = 8 läs 2 — S (E 85! € = 28 LA S| 21/25 x = 58 [5 [2915] td 202/0214 JES

LÖ O g O O MAA ol HLS Wols mou 2 gE |= =

O "28 |< |< SlsiB SSS l TS 52 S | 5 2

E - — O = LV = glee QL = g v S

N — EE |& Jo sla s fö & 5/0 = för: & |< «< — =o = l= S|=|— 8 B= 2 — 2 B= = an an | = © e ZE ele dloslsjssesessessslstääel CS| slag

L 3 e 2 oleig og One ose 2 TS = = [so e = % n .2]8.2/8 C= Q = O x Q = 2 Alef oo | << =

SE CER ER ER SEFEEEBTERTERR 2 | 2/85 2 R >a 2127 ez SEE 8 = 858 8 5/5 8 EA n m IM 2

[0037] As can be seen from Table 1, in each of Examples 1 to 8 as compared with Conventional Example 1, while improving the steering stability on ice and the braking performance on ice, good road surface damage reduction performance is maintained. On the other hand, in Comparative Examples 1 and 2, since only one concentrated region is provided, it is not possible to achieve both improvement of the performance on ice and reduction of the damage to road surfaces.

Reference Signs List

[0038] 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

A Band region a Scattered region

A' Concentrated region

N A” Closely-concentrated region

D

N

Claims

Claims

[Claim 1] A pneumatic tire, comprising: a tread portion (1) extending in a tire circumferential direction and having an annular shape; a pair of sidewall portions (2) respectively disposed on both sides of the tread portion (1); and a pair of bead portions (3) each disposed on an inner side of the pair of sidewall portions (2) in a tire radial direction, the pneumatic tire comprising stud pins (P), the stud pins (P) being implanted in a road contact surface of the tread portion (1), the pneumatic tire comprising a region, as a band region (A), defined between a pair of tire meridians arranged with an interval of 0.8% of a tire circumferential length on a tire equator (CL), a plurality of band regions (A) being arranged over an entire tire circumference while shifting an angle by one degree along a tire circumferential direction, and the plurality of band regions (A) comprising a concentrated region (A’) in which four or more stud pins (P) are provided in the band region (A) and a scattered region (a) in which three or less stud pins (P) are provided in the band region (A), a plurality of the concentrated regions (A’) being intermittently provided along a tire circumferential direction in the plurality of band regions

(A).

[Claim 2] The pneumatic tire according to claim 1, wherein a total number of the stud pins (P) is from 135 to 250. N N [Claim 3] ro The pneumatic tire according to claim 1 or 2, wherein an interval e between the concentrated regions (A’) adjacent to each other in a tire I circumferential direction is 1.0% to 30.0% of a tire circumferential length. a 2 [Claim 4] a The pneumatic tire according to any one of claims 1 to 3, wherein three S to seven closely-concentrated regions (A?) in which five or more stud pins (P) are provided are present in the plurality of concentrated regions (A').

[Claim 5] The pneumatic tire according to claim 4, wherein an interval between the closely-concentrated regions (A) adjacent to each other in a tire circumferential direction is 5.0% to 60.0% of a tire circumferential length.

[Claim 6] The pneumatic tire according to any one of claims 1 to 5, wherein an average protruding amount Px of the stud pins (P) provided in the concentrated regions (A’) and an average protruding amount Pav of the stud pins (P) provided in the scattered regions (a) satisfy a relationship of Px < 0.9 X Pav. N N O N LÖ <Q ™ I a a o <t LO N N O N