Tire

Abstract

To provide a tire which can improve on-snow turning performance and abrasion resistance performance, reduce vulcanization failures, and also obtain excellent plunger testing results.SOLUTION: A tire comprises: a carcass (12); an inclined belt (14) which is formed at an outer side of the carcass in a radial direction of the tire; and cap treads (22) which are formed outside the inclined belt in the radial direction of the tire. When it is defined that, in a view of a tire meridian cross section, a central region in a tread width is a center area and the other region is a shoulder area, hardness of a cap tread rubber (22a) in the shoulder area is higher than that of a cap tread rubber (22b) in the center area, and a width-direction belt (26) including a cord extending at approximately 90 degrees to a tire circumferential direction is formed between the inclined belt and the cap treads.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tire that has improved cornering performance and wear resistance on snow and reduced vulcanization failure. [Background technology]

[0002] Conventionally, even when an asymmetric pattern with a low negative rate on the outer side (OUT side) when mounted on a vehicle is adopted, a tire has been known that has a reinforcing belt that is installed from the outer side when mounted on a vehicle to the inner side when mounted on a vehicle, and that is covered with multiple reinforcing cords that extend in the tire width direction and tire radial direction and are arranged at a predetermined distance between the intersecting belt and the tread, in order to effectively suppress loss of contact pressure during large input cornering and improve cornering performance (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-001588 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the tire disclosed in Patent Document 1, there is a possibility that cap tread rubber with uniform hardness across the tire width direction is used, and therefore the rubber hardness of the shoulder region located on the outer side in the tire width direction within the cap tread region across the tread width is not efficiently increased, and there is a risk that excellent cornering performance and / or wear resistance will not be obtained.

[0005] Furthermore, in winter tires in which sipes are formed on the tread surface in order to set the tread rigidity low and improve straight-line performance on snow and ice, the tire tends to stick to the mold during vulcanization, and there is a risk of the bead portion and / or sidewall portion deforming when the tire is removed from the mold, which is known as vulcanization failure.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a tire that can improve cornering performance and wear resistance on snow and reduce vulcanization failure. [Means for solving the problem]

[0007] The tire of the present invention comprises a carcass, an inclined belt formed radially outward of the carcass, and a cap tread formed radially outward of the inclined belt, and is characterized in that, when viewed in a meridian cross section of the tire, the central region of the tread width is defined as a center region and the remaining regions are defined as shoulder regions, the hardness of the cap tread rubber in the shoulder regions is higher than the hardness of the cap tread rubber in the center region, and a widthwise belt including cords extending at approximately 90 degrees to the tire circumferential direction is formed between the inclined belt and the cap tread (at least in a part of the center region). [Effects of the Invention]

[0008] In the tire according to the present invention, not only is the hardness of the cap tread rubber in the shoulder region set higher than that in the center region, but a widthwise belt including cords extending at approximately 90 degrees relative to the tire circumferential direction is formed between the inclined belt and the cap tread. By setting different rubber hardnesses in the tire width direction for the cap tread, the rigidity of the shoulder region of the tread surface is increased relative to the center region, thereby improving cornering performance on snow and wear resistance. Furthermore, by forming a widthwise belt including cords extending at approximately 90 degrees relative to the tire circumferential direction between the inclined belt and the cap tread, the tire rigidity of the center region, which has a lower rubber hardness than the shoulder region and is prone to sticking to the mold during vulcanization, is increased, thereby reducing vulcanization defects. Therefore, according to the present invention, cornering performance on snow and wear resistance can be improved, while vulcanization defects can be reduced. Furthermore, the formation of the widthwise belt can also obtain good plunger test results. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a meridian cross-sectional view of a tire (tread portion and shoulder portion) according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing suitable and unsuitable examples of the tire width direction dimensions of the width direction belt shown in FIG. [Figure 3] FIG. 3 is a meridian cross-sectional view of a tire showing a modified example of the tire shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing a preferable example and an unpreferable example of the tire radial direction position of the width direction belt shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the following description, the tire radial direction refers to the direction perpendicular to the tire's rotational axis, the tire radially inner side refers to the side toward the rotational axis in the tire radial direction, and the tire radially outer side refers to the side away from the rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the rotational axis as the central axis. The tire width direction refers to the direction parallel to the rotational axis, the tire widthwise inner side refers to the side toward the tire equatorial plane (tire equator line) in the tire width direction, and the tire widthwise outer side refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane is a plane that is perpendicular to the tire's rotational axis and passes through the center of the tire width.

[0011] Similarly, in the following description, a regular rim refers to an "applicable rim" as defined by JATMA, a "design rim" as defined by TRA, or a "measuring rim" as defined by ETRTO.

[0012] Similarly, in the following explanation, "normal internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Inflation Pressures" specified by ETRTO. Also, "normal load" refers to the "maximum load capacity" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Load Capacity" specified by ETRTO.

[0013] Fig. 1 is a meridian cross-sectional view of a tire (tread portion and shoulder portion) according to this embodiment. This figure shows a tire mounted on a standard rim and pressurized to a standard internal pressure in an unloaded state (non-contact state). Although not shown in Fig. 1, the tire 10a (10) according to this embodiment has a typical sidewall portion and bead portion.

[0014] As shown in FIG. 1, a tire 10a (10) of this embodiment includes a carcass 12, an inclined belt 14 consisting of two inclined belt layers 14a, 14b formed on the tire radially outer side of the carcass 12, a belt cover 16 consisting of one belt cover layer 16a formed to cover the tire widthwise outer portions of the inclined belt layers 14a, 14b, an inner liner 18 formed on the inner peripheral side of the carcass 12, a base tread rubber 20 formed on the tire radially outer side of the inclined belt 14 and the belt cover 16, a cap tread rubber 22 formed on the tire radially outer side of the base tread rubber 20, and a sidewall rubber 24 formed on the tire radially inner side of the base tread rubber 20 and the cap tread rubber 22.

[0015] The inclined belt layers 14a and 14b are layers in which a plurality of cords inclined with respect to both the tire width direction and the tire circumferential direction in a plan view of the tire are covered with a rubber member. The inclined belt layers 14a and 14b have the same cord inclination angles with respect to the tire circumferential direction, but in opposite directions.

[0016] In this embodiment, the tire width direction dimension of the inclined belt layer 14a is not particularly limited, but the tire width direction dimension of the inclined belt layer 14b located outermost in the tire radial direction is defined as 65% to 80% of the tire cross-sectional width because it is the basis for the tire width direction dimension of a width direction belt 26 described later.

[0017] The belt cover layer 16a, the base tread rubber 20 and the sidewall rubber 24 are not particularly limited, and commonly used types can be used.

[0018] The thin dotted lines shown in FIG. 1 indicate the boundaries of the rubbers 20, 22, and 24.

[0019] 1, the central region of the tread width is defined as the center region, and the remaining regions are defined as shoulder regions. Here, the center region refers to an area that includes the tire equatorial plane CP and occupies at least 40% of the tread width.

[0020] Under these assumptions, in the tire 10a (10) of this embodiment, the hardness of the cap tread rubber 22a in the shoulder region is higher than the hardness of the cap tread rubber 22b in the center region, and a widthwise belt 26 including cords extending at approximately 90 degrees to the tire circumferential direction is formed between the inclined belt 14 and the cap tread 22 (particularly in the center region).

[0021] Here, the widthwise belts 26 are formed in an area of ​​at least 30% of the central tread width when viewed from above the tire. The cord extension direction of the widthwise belts 26 is within a range of 90°±10° with respect to the tire circumferential direction when viewed from above the tire.

[0022] By making the hardness of the cap tread rubber 22a in the shoulder region higher than the hardness of the cap tread rubber 22b in the center region, the rigidity of the shoulder region can be efficiently increased, thereby improving cornering performance on snow and wear resistance.

[0023] Furthermore, by forming the widthwise belt 26 as a reinforcing layer between the inclined belt 14 and the cap tread 22, it is possible to increase the rigidity of the center region, which has a lower hardness than the shoulder region when looking at the cap tread alone. This prevents the tire from sticking to the mold during vulcanization, prevents deformation of the bead portion and / or sidewall portion when the tire is removed from the mold, and avoids vulcanization failures.

[0024] Furthermore, by setting the cord extension direction of the widthwise belts 26 within a range of 90°±10° relative to the tire circumferential direction when viewed from above, the widthwise belts 26 do not have extreme directionality (i.e., the cords constituting the widthwise belts tend to deviate from the tire width direction), and this can prevent the tire from being destroyed too quickly during a plunger test (a tire destruction test conforming to JIS D 4230, in which a plunger is pressed as far as possible against a protruding portion of the tread pattern in the center of the tire until the tire is destroyed). This effect demonstrated by the plunger test is also exerted during normal vehicle travel. For example, even if the tire runs over a protrusion on the ground, the presence of the widthwise belts 26 can delay tire destruction. Therefore, the above-described cord extension direction of the widthwise belts 26 can improve the durability and impact resistance of the tire.

[0025] The cord extension direction of the width direction belts 26 is more preferably within a range of 90°±8° with respect to the tire circumferential direction when viewed from above the tire, and most preferably within a range of 90°±5° with respect to the tire circumferential direction.

[0026] As described above, the tire 10a (10) of this embodiment can improve the snow cornering performance and the wear resistance, and can reduce the vulcanization failure. In addition, the tire 10a (10) of this embodiment can also obtain good plunger test results.

[0027] The tire of this embodiment is obtained through each of the usual manufacturing steps, i.e., a tire material mixing step, a tire material processing step, a green tire molding step, a vulcanization step, and a post-vulcanization inspection step, etc. When manufacturing the tire of this embodiment, in particular, recesses and protrusions corresponding to the desired tread pattern are formed on the inner wall of a vulcanization mold, and vulcanization is carried out using this mold.

[0028] In the tire shown in FIG. 1, it is preferable that the JIS hardness (Durometer hardness of Type A of JIS K6253-3:2023; the same applies below) of the cap tread rubber 22a in the shoulder region is 52 or more and 58 or less, and the JIS hardness of the cap tread rubber 22b in the center region is 42 or more and 48 or less.

[0029] By making the JIS hardness of the cap tread rubber 22a in the shoulder region 52 or more, the rigidity of the shoulder region can be further increased, and in turn, the cornering performance on snow and the wear resistance can be further improved.

[0030] In contrast, by setting the JIS hardness of the cap tread rubber 22a in the shoulder region to 58 or less, it is possible to prevent cracks from occurring at the boundary between the rubbers 22a and 22b when the tire is rolling, without making the hardness of the cap tread rubber 22a in the shoulder region and the hardness of the cap tread rubber 22b in the center region too different, thereby preventing cracks from occurring at the boundary between the rubbers 22a and 22b when the tire is rolling.

[0031] The JIS hardness of the cap tread rubber 22a in the shoulder region is more preferably 53 or more and 57 or less, and most preferably 54 or more and 56 or less.

[0032] By setting the JIS hardness of the cap tread rubber 22b in the center region to 42 or more, it is possible to prevent cracks from occurring at the boundary between the rubbers 22a and 22b when the tire is rolling, without making the hardness of the cap tread rubber 22a in the shoulder region and the hardness of the cap tread rubber 22b in the center region too different.

[0033] In contrast, by setting the JIS hardness of the cap tread rubber 22b in the center region to 48 or less, the rigidity of the tread surface in the center region is set low, and the edge effect of the land area separated by the sipes formed in the center region is fully utilized, thereby improving straight-line running performance on snow, braking performance on snow, etc.

[0034] The JIS hardness of the cap tread rubber 22b in the center region is more preferably 43 or more and 47 or less, and most preferably 44 or more and 46 or less.

[0035] In the tire shown in FIG. 1, the cap tread 22 in the center region is preferably formed in a range of 40% to 80% of the tread width.

[0036] By forming the cap tread 22 in the center region to cover an area of ​​40% or more of the tread width, it is possible to use rubber with a relatively low hardness and to secure a sufficient center region to ensure snow-clearing action based on the edge effect of the land area separated by sipes, thereby further improving straight-line running performance and braking performance on snow.

[0037] By forming the cap tread 22b in the center region to a range of 80% or less of the tread width, sufficient shoulder area can be secured using rubber with relatively high hardness, thereby further improving cornering performance on snow and wear resistance.

[0038] The cap tread 22b in the center region is more preferably formed in a range of 45% to 75% of the tread width, and most preferably in a range of 50% to 70% of the tread width.

[0039] Fig. 2 is a schematic diagram showing suitable and unsuitable examples of the tire width direction dimension of the width direction belt shown in Fig. 1. More specifically, Fig. 2 shows the inclined belt layers 14a, 14b and the width direction belts 26 (26a to 26c) shown in Fig. 1, and Fig. 2 is a diagram comparing, in particular, the tire width direction dimension of the radially outermost inclined belt layer 14b with the tire width direction dimension of the width direction belt 26. In Fig. 2, A is a conventional example in which the width direction belt 26 is not present, B is an unsuitable example in which the tire width direction dimension of the width direction belt 26a is less than 40% of the tire width direction dimension of the inclined belt layer 14b, C is a suitable example in which the tire width direction dimension of the width direction belt 26b is 40% to 80% of the tire width direction dimension of the inclined belt layer 14b, and D is an unsuitable example in which the tire width direction dimension of the width direction belt 26c is more than 80% of the tire width direction dimension of the inclined belt layer 14b.

[0040] As described above, the tire of this embodiment includes a widthwise belt 26. As shown in FIG. 2B, when the tire widthwise dimension of the widthwise belt 26a is less than 40% of the tire widthwise dimension of the inclined belt layer 14b, the tire widthwise dimension of the inclined belt layer 14b and the tire widthwise dimension of the widthwise belt 26a are excessively different. Therefore, under conditions in which the tire is subjected to an impact exceeding the normal load, the tire elements 14b, 26a will flex significantly differently. This difference in flexure may occur multiple times, resulting in the so-called standing wave phenomenon. Furthermore, when the tire elements 14b, 26a flex significantly differently, the tire elements 14b, 26a may not be evenly distributed on both sides of the tire equatorial plane CP, which may result in degradation of tire uniformity.

[0041] 2D, when the tire width direction dimension of the width direction belt 26c is more than 80% of the tire width direction dimension of the inclined belt layer 14b, the tire width direction dimension of the width direction belt 26c becomes excessively long. Therefore, under conditions in which the tire is subjected to an impact exceeding the normal load, the end of the width direction belt 26c is likely to be located at a position where the tire is most severely bent when viewed as a whole, and the end becomes a bending point, which may cause cracks and deteriorate tire durability.

[0042] Unlike these unsuitable examples (B and D in Fig. 2), when the tire width direction dimension of the width direction belt 26b is 40% to 80% of the tire width direction dimension of the inclined belt layer 14b as shown in C in Fig. 2, undesirable phenomena (standing wave phenomenon, deterioration of tire uniformity, and deterioration of tire durability) caused by the length of the width direction belt 26, as in the examples of B in Fig. 2 and D in Fig. 2, do not occur. For this reason, it is preferable that the tire width direction dimension of the width direction belt 26 is 40% to 80% of the tire width direction dimension of the radially outermost inclined belt layer 14b.

[0043] The tire width direction dimension of the width direction belt 26 is more preferably 45% to 75% of the tire width direction dimension of the inclined belt layer 14b, and most preferably 50% to 70%.

[0044] 2B to 2D show an example in which the inclined belt 14 is made up of two inclined belt layers 14a and 14b, but the tire 10a (10) of this embodiment is not limited to this example and also includes an example in which the inclined belt 14 is made up of three or more inclined belt layers. Even when the inclined belt 14 is made up of three or more inclined belt layers, the object to be compared with the tire width direction dimension of the width direction belt 26 is the inclined belt layer on the outermost side in the tire radial direction.

[0045] Fig. 3 is a tire meridian cross-sectional view showing a modified example of the tire shown in Fig. 1. In the tire 10b(10) shown in Fig. 3, the carcass 12, the inclined belt 14, the inner liner 18, the base tread rubber 20, the cap tread rubber 22, and the sidewall rubber 24 are the same as those in the example shown in Fig. 1. However, in the example shown in Fig. 3, the shape and the position of the belt cover 16 are different from those in the example shown in Fig. 1. That is, in the example shown in Fig. 3, the belt cover 16 is made up of two belt cover layers 16b, 16c, and these belt cover layers 16b, 16c cover the entire inclined belt layers 14a, 14b and the width direction belt 26 from the outer side in the tire radial direction.

[0046] The belt cover layers 16b, 16c have a tire width direction dimension of 70% to 85% of the tire cross-sectional width. The belt cover layers 16b and 16c have cord inclination angles opposite to but equal to the tire circumferential direction.

[0047] Fig. 4 is a schematic diagram showing suitable and unsuitable examples of the tire radial position of the widthwise belt shown in Fig. 3. More specifically, Fig. 4 shows the inclined belt layers 14a, 14b, belt cover layers 16b, 16c, and widthwise belts 26 (26d to 26f) shown in Fig. 3, and particularly shows the tire radial position of the widthwise belt 26 relative to the inclined belt layers 14a, 14b, and belt cover layers 16b, 16c. In Fig. 4, E is a conventional example in which the widthwise belt 26 is not present, F is an unsuitable example in which the widthwise belt 26d is located radially inward of the innermost inclined belt 14a, G is a suitable example in which the widthwise belt 26e is located radially between the inclined belt layer 14 and the belt cover 16, and H is an unsuitable example in which the widthwise belt 26f is located radially outward of the outermost belt cover layer 16c.

[0048] As described above, the tire of this embodiment includes the width direction belts 26. When the width direction belts 26d are positioned radially inward of the radially innermost inclined belts 14a, as shown in Fig. 4F, even if an attempt is made to compensate for the rigidity of the center region, which has a lower hardness than the shoulder regions when only the cap tread 22 is viewed, by using the width direction belts 26, it is not possible to increase the rigidity near the tread surface to an extent that can prevent the tire from sticking to the mold during vulcanization, and there is a risk that the bead portions and / or sidewall portions will deform when the tire is removed from the mold.

[0049] Furthermore, as shown in FIG. 4H, when the widthwise belt 26f is positioned radially outward of the radially outermost belt cover layer 16c, in a situation where an impact exceeding the normal load is applied to the tire, the end of the widthwise belt 26f is likely to be located at a position that is most severely bent when viewed as a whole tire, and the end becomes a bending point, which may cause cracks and deteriorate the durability of the tire.

[0050] Unlike these unsuitable examples (F and H in Fig. 4), when the widthwise belt 26e is positioned between the inclined belt layer 14 and the belt cover 16 in the tire radial direction as shown in G in Fig. 4, undesirable phenomena resulting from the tire radial position of the widthwise belt 26 (deformation of the bead portion and / or sidewall portion when the tire is removed from the mold, and cracks occurring due to the end of the widthwise belt becoming a bending point) do not occur as in the examples of F in Fig. 4 and H in Fig. 4. For this reason, it is preferable that the widthwise belt 26 is formed on the outer side of the inclined belt 14 in the tire radial direction and on the inner side of the belt cover 16 in the tire radial direction.

[0051] 1 or 3, the cords of the width direction belts 26 may be steel cords or organic fiber cords. In particular, when the cords of the width direction belts 26 are steel cords, the width direction belts 26 are preferably excellent in strength, processability, and corrosion resistance.

[0052] In the example shown in FIG. 1 or FIG. 3, it is preferable that a plurality of sipes are formed on the tire surface and that the snow traction index (STI) is 180 or more.

[0053] Here, the Snow Traction Index (STI) is an index that indicates the level of performance on snow, calculated from the tire cross-sectional direction (tire width direction) components of the length of the grooves and kerfs (sipes) on the surface of the tread pattern described in SAE Paper 820345 and the groove depth, and is defined by the following formula: STI=-6.8+2202·ρg+672·ρs+7.6·Dg

[0054] As the STI increases, the tire's performance on snow improves, but if it becomes too large, rigidity decreases and dry performance (performance on dry roads) decreases.

[0055] In the above formula, ρg is the total length (mm) of all grooves provided in the contact patch projected in the tire width direction, expressed as (contact patch width x circumference) (mm 2 ) and ρs is the total length (mm) of all sipes formed in the contact area projected in the tire width direction, divided by (contact area width x circumference) (mm 2 ), and Dg is the average depth (mm) of the grooves in the contact patch. Here, the contact patch refers to the surface area of ​​the tire that comes into contact with the road when the tire is mounted on a rim, pressurized to the standard internal pressure, and subjected to a load of 75% of the standard internal pressure.

[0056] In this specification, a groove refers to a recessed portion having a width of 3.0 mm or more and a depth of 6.0 mm or more, whereas a sipe refers to a recessed portion having a width of less than 1.0 mm and a depth of less than 8.0 mm. Furthermore, the width of a groove (sipe) refers to the dimension (maximum value) of the groove (sipe) measured in a direction perpendicular to the direction in which the groove (sipe) extends, and the depth of a groove (sipe) refers to the dimension (maximum value) of the groove (sipe) measured in the radial direction of the tire from the profile line in the event that the groove (sipe) does not exist.

[0057] By making the Snow Traction Index (STI) 180 or higher, it is possible to further improve performance on snow (turning performance on snow, straight-line running performance on snow, stability on snow, braking performance on snow, etc.). It is more preferable to make the Snow Traction Index (STI) 185 or higher, and it is extremely preferable to make it 190 or higher. [Example]

[0058] Test tires (comparative tire and invention examples 1 to 7) were manufactured with a tire size of 235 / 60R19 107Q (specified by JATMA), a common tire meridian cross section shape shown in FIG. 3 except for the widthwise belt, and satisfying the conditions shown in Table 1. Note that all terms in Table 1 are equivalent to the terms explained in this embodiment. For each test tire, snow cornering performance, wear resistance, vulcanization failure resistance, and plunger test were evaluated as follows.

[0059] (Snow turning performance) Each test tire was mounted on a 19x7.0J rim, with both the front and rear wheels inflated to 230 kPa. A test vehicle (a 2500cc 4WD vehicle) with chains attached to the drive wheels was driven on a snow test course simulating an urban area, and a sensory evaluation was conducted by a test driver. This evaluation was an index evaluation with the comparative example as the standard (100). The evaluation results are also shown in Table 1. In this evaluation result, the higher the numerical value, the better the snow cornering performance.

[0060] (Wear resistance) Each test tire was mounted on a 19x7.0J rim, and both the front and rear wheels were inflated to 230 kPa. A test vehicle (a 2500cc 4WD vehicle) was driven 8000 km on a designated off-road course, after which the difference in wear between the land areas in the shoulder region and the land area in the center region of the tread was measured and evaluated. This evaluation was performed using an index rating with the comparative example as the standard (100). The evaluation results are also shown in Table 1. In this evaluation result, the higher the numerical value, the higher the wear resistance performance.

[0061] (Vulcanization failure resistance) One hundred tires of each type were manufactured, and the rate at which vulcanization failure occurred (vulcanization failure rate), in which the tire stuck to the mold during vulcanization and the bead and / or sidewall were deformed when the tire was removed from the mold, was calculated and evaluated. This evaluation was performed using an index evaluation with the comparative example as the standard (100). The evaluation results are also shown in Table 1. In this evaluation result, the higher the numerical value, the higher the resistance to vulcanization failure.

[0062] (Plunger test) Each test tire was mounted on a 19x7.0J rim and inflated to 180 kPa. After leaving the tire at room temperature for three hours, the air pressure was adjusted back to 180 kPa. A 38 mm diameter plunger attached to a plunger test device was pressed against the tire at a rate of 50.0 ± 2.5 mm per minute. The plunger's thrust force and travel distance just before the tire broke were measured. Half the product of this thrust force and travel distance was considered to be the fracture energy, and the fracture energy was evaluated using an index with the comparative example as the standard (100). The evaluation results are also shown in Table 1. In this evaluation result, a higher value indicates a better plunger test result.

[0063] [Table 1]

[0064] Table 1 shows that tires according to Example 1 to Example 7, which fall within the technical scope of the present invention (i.e., the hardness of the cap tread rubber in the shoulder region is higher than that in the center region, and a widthwise belt including cords extending at approximately 90 degrees to the tire circumferential direction is formed between the inclined belt and the cap tread), all have improved cornering performance on snow, wear resistance, and resistance to vulcanization failure compared to tires according to the comparative example, which do not fall within the technical scope of the present invention. Furthermore, it was confirmed that tires according to Example 1 to Example 7 also performed well in plunger tests. [Explanation of symbols]

[0065] 10, 10a, 10b tires 12 Carcass 14 Inclined Belt 14a, 14b Inclined belt layer 16 Belt cover 16a, 16b, 16c Belt cover layer 18 Inner liner 20 Base tread rubber 22 Cap tread rubber 22a Cap tread rubber in shoulder area 22b Cap tread rubber in the center area 24 Sidewall rubber 26, 26a, 26b, 26c, 26d, 26e, 26f Width direction belt CP tire equatorial plane

Claims

1. A tire comprising: a carcass; an inclined belt formed on the tire radial direction outer side of the carcass; and a cap tread formed on the tire radial direction outer side of the inclined belt, When viewed in meridian section of the tire, the central region of the tread width is defined as a center region and the remaining regions are defined as shoulder regions, the hardness of the cap tread rubber in the shoulder regions is higher than the hardness of the cap tread rubber in the center region, and a widthwise belt including cords extending at approximately 90 degrees to the tire circumferential direction is formed between the inclined belt and the cap tread.

2. 2. The tire according to claim 1, wherein the cap tread rubber in the shoulder region has a JIS hardness of 52 or more and 58 or less, and the cap tread rubber in the center region has a JIS hardness of 42 or more and 48 or less.

3. The tire according to claim 1 or 2, wherein the cap tread in the center region is formed in a range of 40% to 80% of the tread width.

4. The tire according to claim 1 or 2, wherein a dimension in the tire width direction of the width direction belt is 40% to 80% of a dimension in the tire width direction of the outermost inclined belt layer in the tire radial direction.

5. 3. The tire according to claim 1, further comprising a belt cover on the tire radially outer side of the inclined belt, wherein the width direction belt is formed on the tire radially outer side of the inclined belt and on the tire radially inner side of the belt cover.

6. 3. The tire according to claim 1, wherein the cords of the transverse belts are made of steel.

7. 3. The tire according to claim 1, wherein a plurality of sipes are formed on the tire surface, and the tire has a snow traction index (STI) of 180 or more.

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