Heavy-duty tire

Abstract

In a heavy-duty tire according to the present invention, a tread part is provided with a belt composed of one or more belt layers, and one or more belt reinforcement layers disposed on the outer side of the belt in the tire radial direction. The belt reinforcement layer is formed by coating reinforcement cords with rubber. Each of the reinforcement cords extends from one end to the other end of the belt reinforcement layer and is cut at the one end and the other end. Each of the reinforcement cords is furthermore divided at one or more locations between the one end and the other end. The division positions of the reinforcement cords are positioned on the same straight line across the plurality of reinforcement cords.

Description

Heavy-duty tires

[0001] The present invention relates to a heavy duty tire.

[0002] In heavy-duty tires, a configuration is known in which a belt reinforcing layer is provided on the radially outer side of the belt layer to protect the belt layer, which has a hoop function, from obstacles such as fallen objects and stones on the road (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2001-301418

[0004] However, even if the belt reinforcing layer is provided, there are cases where the belt reinforcing layer is broken by an obstacle, and the belt layer is damaged.

[0005] Therefore, an object of the present invention is to provide a heavy-duty tire that can suppress damage to the belt layer caused by obstacles on the road by providing a belt reinforcing layer with sufficient breaking strength.

[0006] The gist of the present invention is as follows: (1) A heavy-duty tire having, in a tread portion, a belt consisting of one or more belt layers, and one or more belt reinforcing layers arranged radially outward of the belt, wherein the belt reinforcing layer is made of rubber-coated reinforcing cords, each of the reinforcing cords extends from one end to the other end of the belt reinforcing layer and is cut at the one end and the other end, each of the reinforcing cords is further divided at one or more locations between the one end and the other end, and the division positions of the reinforcing cords are located on the same straight line across a plurality of the reinforcing cords.

[0007] According to the present invention, it is possible to provide a heavy-duty tire that can suppress damage to the belt layer due to obstacles on the road by providing the belt reinforcing layer with sufficient breaking strength.

[0008] 3A and 3B are plan views of a first modified example of a belt reinforcing layer; FIG. 3B is a plan view of a second modified example of a belt reinforcing layer; FIG. 3C is a diagram showing the results of an example; FIG. 3D is a diagram showing an example of the arrangement of a communication device; FIG. 3E is a diagram showing the state in which fibers are laid on a rubber block and a protrusion is pressed in from above; FIG. 3F is a diagram showing the state in which a rubber block is deformed when fibers are laid on a rubber block and a protrusion is pressed in from above; FIG. 3G is a diagram showing the relationship between the fiber length and the tensile force of the fiber immediately below the protrusion in the cases of FIGS. 3A and 3B; FIG. 3H is a plan view of a first modified example of a belt reinforcing layer; FIG. 3I is a diagram showing the results of an example; FIG. 3J is a diagram showing an example of the arrangement of a communication device;

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0010] Unless otherwise specified, the dimensions and positional relationships below refer to the dimensions and positional relationships in the standard state when a heavy-duty tire (hereinafter simply referred to as "tire") is mounted on an applicable rim, inflated to the specified internal pressure, and no load is applied.

[0011] In this specification, the term "applicable rim" refers to the standard rim (referred to as "Measuring Rim" in the ETRTO STANDARDS MANUAL and "Design Rim" in the TRA YEAR BOOK) for the applicable size, which is an industry standard valid in the region where the tire is produced and used, and which is described or will be described in the future in the JATMA YEAR BOOK of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the STANDARDS MANUAL of the European Tire and Rim Technical Organization (ETRTO) in Europe, the YEAR BOOK of the Tire and Rim Association, Inc. (TRA) in the United States, etc. "rim" refers to the tire's width corresponding to the tire's bead width (i.e., the "rim" in the above "wheel" includes not only current sizes but also sizes that may be included in the above industry standards in the future. Examples of "sizes to be described in the future" include sizes listed under "FUTURE DEVELOPMENTS" in the 2013 edition of ETRTO). However, for sizes not listed in the above industry standards, it refers to a rim with a width corresponding to the tire's bead width. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size / ply rating listed in the above JATMA etc., and for sizes not listed in the above industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. Furthermore, "maximum applied load" described below refers to the load corresponding to the above maximum load capacity.

[0012] 1 is a cross-sectional view in the tire width direction showing a tread portion of a tire. The tire includes a pair of bead portions, a pair of sidewall portions connected to the pair of bead portions, and a tread portion 1 connected between the sidewall portions. The tire also includes a carcass that toroidally straddles the pair of bead portions. The bead portions and the carcass can have known configurations, so detailed description thereof will be omitted.

[0013] As shown in FIG. 1, a tread portion 1 includes a belt 2 consisting of one or more belt layers (three belt layers 2a, 2b, and 2c in the illustrated example), and one or more belt reinforcing layers 3 (one layer in the illustrated example) arranged radially outward of the belt 2.

[0014] Each of the belt layers 2a, 2b, and 2c is formed by rubber-coating belt cords. In this example, the belt layers 2a, 2b, and 2c are inclined belt layers in which the belt cords cross each other between the layers. Although not particularly limited, each belt cord can be inclined at an inclination angle of, for example, 5 to 60 degrees with respect to the tire circumferential direction. In the illustrated example, the width of the belt layer 2b in the tire width direction is the largest. On the other hand, the belt layer may be one or more layers, and the number of belt layers and the width of the belt layer in the tire width direction can vary. Although not particularly limited, the belt cord can be a steel cord.

[0015] The belt reinforcing layer 3 is formed by rubber-coating reinforcing cords. Each reinforcing cord extends from one end to the other end of the belt reinforcing layer 3 and is cut at both ends. That is, the reinforcing cord extends at an angle relative to the tire circumferential direction. The angle of inclination of the reinforcing cord relative to the tire circumferential direction is not particularly limited, but may be, for example, 5 to 60 degrees. The reinforcing cord is not particularly limited, but it is preferable to use a cord made of a material with sufficient breaking strength, such as a steel cord or an organic fiber such as nylon or aramid.

[0016] Fig. 2 is a plan view of the belt reinforcing layer. As shown in Fig. 1 and Fig. 2, each of the reinforcing cords is further divided at one or more locations between one end and the other end (in Fig. 1, the reinforcing cords shown by circles are undivided locations, and the reinforcing cords shown by circles with vertical lines are divided locations). In this example, the divided reinforcing cords are in a state where at least a portion of the divided surfaces contact each other.

[0017] Here, the division positions of the reinforcing cords are located on the same straight line across a plurality of reinforcing cords (in the illustrated example, the same straight line extends in the tire circumferential direction). Hereinafter, the effects of the heavy duty tire of this embodiment will be described.

[0018] In the heavy-duty tire of this embodiment, the belt reinforcing layer 3 is disposed radially outward of the belt 2, and the belt reinforcing layer 3 functions to protect the belt 2. Fig. 3A is a diagram showing how fibers 5 are laid on a rubber block 4 and protrusions 6 are pressed in from above. Fig. 3B is a diagram showing how the rubber block 6 deforms when fibers 5 are laid on the rubber block 4 and protrusions 6 are pressed in from above. Fig. 4 is a diagram showing the relationship between the fiber length and the tensile force of the fiber directly below the protrusions in this case.

[0019] The tensile force acting on a reinforcing cord, which can cause the reinforcing cord to break, is the sum of the rubber shear forces acting along the reinforcing cord (shear deformation is schematically shown by small squares in FIG. 3B ). As shown in FIG. 4 , shortening the fiber length can reduce the sum of the rubber shear forces acting along the fiber. In this embodiment, each reinforcing cord is further divided at one or more locations between its ends, thereby reducing the sum of the rubber shear forces acting along the reinforcing cord and making the reinforcing cord less likely to break. This reduces the resistance of the belt reinforcing layer 3 to break, allowing the belt reinforcing layer 3 to fully fulfill its function of protecting the belt 2 (e.g., from obstacles such as falling objects and stones). Furthermore, because the division positions of the reinforcing cords are located on the same straight line across multiple reinforcing cords, the heavy-duty tire described above can be manufactured by performing a cutting process on the same straight line, resulting in excellent manufacturability. Another advantage is that weight is not increased compared to simply increasing the diameter of the reinforcing cord, increasing the number of ends per cord, or increasing the number of belt reinforcing layers. As described above, according to the heavy duty tire of this embodiment, the belt reinforcing layer has sufficient breaking strength, so that damage to the belt layer due to obstacles on the road can be suppressed.

[0020] Here, in a cross section in the tire width direction, the sum of the cross-sectional areas of the multiple reinforcing cords relative to the cross-sectional area of ​​the belt reinforcing layer (the sum of the cross-sectional area of ​​the reinforcing cords and the cross-sectional area of ​​the covering rubber) is preferably equal to or greater than the sum of the cross-sectional areas of the multiple belt cords in the outermost belt layer (belt layer 2c in the illustrated example) located outermost in the tire radial direction among one or more belt layers relative to the cross-sectional area (the sum of the cross-sectional area of ​​the belt cords and the cross-sectional area of ​​the covering rubber). This is because the belt reinforcing layer 3 can have an even more sufficient protective function for the belt 2.

[0021] The division positions of each reinforcing cord are preferably at the same position in the tire width direction when viewed in the tire circumferential direction, because this prevents uneven rigidity in the tire circumferential direction, thereby preventing uneven wear and noise caused by uneven rigidity.

[0022] Each divided reinforcement cord preferably has a width in the tire width direction that is 6.25 to 50% of the width in the tire width direction of the belt reinforcement layer 3. By making the width 50% or less, the effect of improving the breaking strength of the reinforcement cord can be made more sufficient, while by making the width 6.25% or more, it is possible to prevent the reinforcement cord from being too short and being pulled out, which makes it impossible to exert its protective function, and also to suppress a decrease in productivity during production.

[0023] It is preferable that the divided surfaces of each divided reinforcing cord are in at least partial contact with each other (in the example shown in FIG. 2, at least partial contact (in the illustrated example, the entire surface) is present in all divided surfaces). This is because it is possible to prevent obstacles from penetrating gaps that are generated when the cut ends are separated. FIG. 5 is a plan view of a first modified example of the belt reinforcing layer. As shown in FIG. 5, the divided surfaces of each divided reinforcing cord may be spaced apart. FIG. 6 is a plan view of a second modified example of the belt reinforcing layer. As shown in FIG. 6, the divided reinforcing cords may include a mixture of divided reinforcing cords in which at least partial contact is present and divided reinforcing cords in which the divided surfaces are spaced apart. The state in which at least partial contact is present includes a state in which the divided surfaces are in contact with each other while overlapping in the radial direction and a state in which the divided surfaces are in contact with each other while overlapping in the circumferential direction.

[0024] Here, the width of the belt reinforcing layer 3 in the tire width direction is preferably 30% or more of the tread width. Furthermore, the ends of the belt reinforcing layer 3 are preferably located more inward in the tire width direction than the tread ends. By making the width of the belt reinforcing layer 3 in the tire width direction 30% or more of the tread width, the widthwise range over which the belt reinforcing layer protects the belt can be widened, thereby enhancing the protective function. Furthermore, by positioning the ends of the belt reinforcing layer 3 more inward in the tire width direction than the tread ends, the weight increase of the belt reinforcing layer (and thus the tire weight increase) can be suppressed. Here, "tread ends" refers to both ends in the tire width direction of the tread surface of the tread portion that will come into contact with the road surface when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and subjected to a maximum load. Furthermore, "tread width" refers to the distance in the tire width direction between both tread ends in an unloaded state.

[0025] Furthermore, it is preferable that the division position of each reinforcement cord is offset in the tire width direction from the circumferential main groove. This is because it prevents the cut end position from moving due to pressure applied to the reinforcement cord by the mold part that forms the groove during vulcanization molding of the raw tire, and more reliably exerts the protection function of the belt. There are no particular limitations on the method for dividing the reinforcement cord, but as an example, the belt before vulcanization molding can be divided into multiple narrow pieces.

[0026] [Example of Arrangement of Communication Device] FIG. 8 is a diagram showing an example of arrangement of a communication device. A tire may include an RF tag as the communication device 100. The RF tag includes an IC chip and an antenna. The RF tag may be arranged, for example, sandwiched between multiple components of the same or different types that constitute the tire. This makes it easier to attach the RF tag during tire production, improving the productivity of tires equipped with RF tags. In this example, the RF tag may be arranged, for example, sandwiched between a bead filler and another component adjacent to the bead filler. The RF tag may be embedded in any of the components that constitute the tire. This reduces the load on the RF tag compared to when the RF tag is arranged sandwiched between multiple components that constitute the tire. This improves the durability of the RF tag. In this example, the RF tag may be embedded in a rubber component such as tread rubber or side rubber. It is preferable that the RF tag is not arranged at a position that is a boundary between components with different rigidities in the periphery length direction, which is the direction along the outer surface of the tire in a cross-sectional view in the tire width direction. By doing so, the RF tag is not placed in a position where distortion is likely to concentrate due to a difference in rigidity. Therefore, the load applied to the RF tag can be reduced. This can improve the durability of the RF tag. In this example, it is preferable that the RF tag is not placed in a position that is, for example, the boundary between the end of the carcass and a member adjacent to the end of the carcass (for example, a side rubber, etc.) in a cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. A tire may be equipped with only one RF tag, or may be equipped with two or more RF tags. Here, an RF tag is described as an example of a communication device, but a communication device other than an RF tag may also be used.

[0027] The RF tag may be disposed, for example, in the tread portion of the tire. In this manner, the RF tag will not be damaged by a side cut of the tire. The RF tag may be disposed, for example, in the tread center portion in the tire width direction. The tread center portion is a position in the tread portion where flexure is less likely to concentrate. In this manner, the load applied to the RF tag can be reduced. This improves the durability of the RF tag. Also, it is possible to prevent differences in communication with the RF tag from both outer sides of the tire in the tire width direction. In this example, the RF tag may be disposed, for example, within a range of 1 / 2 of the tread width centered on the tire equatorial plane in the tire width direction. The RF tag may be disposed, for example, at the tread edge in the tire width direction. If the position of a reader that communicates with the RF tag is predetermined, the RF tag may be disposed, for example, at the tread edge on one side closer to the reader. In this example, the RF tag may be disposed, for example, within a range of 1 / 4 of the tread width in the tire width direction, with the tread edge as the outer end.

[0028] The RF tag may be positioned, for example, closer to the tire cavity than a carcass including one or more carcass plies spanning between bead portions. This configuration makes the RF tag less susceptible to damage from impacts applied from outside the tire or damage such as side cuts or nail penetration. As an example, the RF tag may be positioned in close contact with the surface of the carcass facing the tire cavity. As another example, if there is another component closer to the tire cavity than the carcass, the RF tag may be positioned, for example, between the carcass and another component located closer to the tire cavity than the carcass. An example of another component located closer to the tire cavity than the carcass is an inner liner that forms the tire inner surface. As another example, the RF tag may be attached to the tire inner surface facing the tire cavity. Configuring the RF tag to be attached to the tire inner surface makes it easier to attach the RF tag to the tire and to inspect and replace the RF tag. In other words, the ease of attaching and maintaining the RF tag can be improved. Furthermore, by attaching the RF tag to the inner surface of the tire, it is possible to prevent the RF tag from becoming a nucleus of tire failure, compared to a configuration in which the RF tag is embedded in the tire. Furthermore, when the carcass has multiple carcass plies and there is a position where multiple carcass plies are overlapped, the RF tag may be disposed between the overlapped carcass plies.

[0029] The RF tag may be arranged, for example, in the tread portion of the tire, radially outward of a belt including one or more belt plies. As one example, the RF tag may be arranged radially outward of the belt in the tire radial direction and in close contact with the belt. Alternatively, the RF tag may be arranged radially outward of the belt reinforcing layer in the tire radial direction and in close contact with the belt layer. As another example, the RF tag may be embedded in the tread rubber radially outward of the belt reinforcing layer. By arranging the RF tag radially outward of the belt in the tread portion of the tire, communication with the RF tag from the outside of the tire in the tire radial direction is less likely to be obstructed by the belt. Therefore, communication with the RF tag from the outside of the tire in the tire radial direction can be improved. Alternatively, the RF tag may be arranged radially inward of the belt in the tread portion of the tire. In this way, the outside of the RF tag in the tire radial direction is covered by the belt, making the RF tag less susceptible to damage from impacts from the tread surface or nail penetration. As one example, the RF tag may be disposed in the tread portion of the tire between the belt and the carcass located radially inward of the belt. Furthermore, if the belt has multiple belt plies, the RF tag may be disposed in the tread portion of the tire between any two belt plies. In this manner, the outer side of the RF tag in the tire radial direction is covered by one or more belt plies, making the RF tag less susceptible to damage from impacts from the tread surface, nail penetration, and the like.

[0030] The RF tag may be disposed, for example, sandwiched between the cushion rubber and the tread rubber or between the cushion rubber and the side rubber. In this way, the cushion rubber can absorb impacts on the RF tag. This improves the durability of the RF tag. The RF tag may also be embedded in the cushion rubber. Furthermore, the cushion rubber may be composed of multiple adjacent rubber members of the same or different types. In such a case, the RF tag may be disposed sandwiched between the multiple rubber members that make up the cushion rubber.

[0031] The RF tag may be disposed, for example, in a sidewall portion or a bead portion of the tire. The RF tag may be disposed, for example, in one sidewall portion or one bead portion that is closer to a reader capable of communicating with the RF tag. This improves communication between the RF tag and the reader. As an example, the RF tag may be disposed between the carcass and the side rubber or between the tread rubber and the side rubber. The RF tag may be disposed, for example, between the tire's maximum width position and the tread surface position in the tire radial direction. This improves communication with the RF tag from the tire's outer side in the tire radial direction compared to a configuration in which the RF tag is disposed radially inward of the tire's maximum width position. The RF tag may be disposed, for example, radially inward of the tire's maximum width position. This allows the RF tag to be disposed near the bead portion, which has high rigidity. This reduces the load applied to the RF tag. This improves durability of the RF tag. As an example, the RF tag may be disposed adjacent to the bead core in the tire radial direction or the tire width direction. Strain is less likely to concentrate near the bead core. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag. In particular, it is preferable that the RF tag be positioned radially inward of the tire's maximum width position and radially outward of the bead core of the bead portion. This improves the durability of the RF tag, and communication between the RF tag and a reader is less likely to be obstructed by the bead core, thereby improving the communication performance of the RF tag. Furthermore, when the side rubber is composed of multiple rubber members of the same or different types adjacent to each other in the tire radial direction, the RF tag may be sandwiched between the multiple rubber members that make up the side rubber. The RF tag may be sandwiched between a stiffener and a member adjacent to the stiffener. This allows the RF tag to be positioned in a position where strain is less likely to concentrate due to the stiffener. Therefore, the load on the RF tag can be reduced. This improves the durability of the RF tag.The RF tag may be disposed, for example, sandwiched between the stiffener and the side rubber. The RF tag may also be disposed, for example, sandwiched between the stiffener and the carcass. The portion of the carcass that sandwiches the RF tag together with the stiffener may be located on the outer side of the stiffener in the tire width direction, or on the inner side of the tire width direction. When the portion of the carcass that sandwiches the RF tag together with the stiffener is located on the outer side of the stiffener in the tire width direction, the load applied to the RF tag due to impact or damage from the outside of the tire in the tire width direction can be further reduced. This can further improve the durability of the RF tag. The stiffener may have a portion that is located adjacent to the rubber chafer. In such a case, the RF tag may be disposed, sandwiched between the stiffener and the rubber chafer. The stiffener may have a portion that is adjacent to the hat rubber on the outer side in the tire width direction. In such a case, the RF tag may be disposed, sandwiched between the stiffener and the hat rubber. The stiffener may be made up of a plurality of rubber members with different hardness. In such a case, the RF tag may be arranged sandwiched between the plurality of rubber members that make up the stiffener. The RF tag may be arranged sandwiched between the hat rubber and a member adjacent to the hat rubber. The RF tag may be arranged sandwiched between the hat rubber and the carcass ply, for example. In this way, the impact on the RF tag can be mitigated by the hat rubber. Therefore, the durability of the RF tag can be improved.

[0032] The RF tag may be arranged, for example, sandwiched between the rubber chafer and the side rubber. In this way, the RF tag can be arranged in a position where the placement of the rubber chafer makes it less likely for distortion to concentrate. This reduces the load on the RF tag. This improves the durability of the RF tag. The RF tag may be arranged, for example, sandwiched between the rubber chafer and the carcass. In this way, it reduces the load on the RF tag due to impacts or damage from the rim. This improves the durability of the RF tag.

[0033] The RF tag may be disposed sandwiched between the nylon chafer and another member adjacent to the nylon chafer on the outer or inner side in the tire width direction. This makes it difficult for the position of the RF tag to fluctuate when the tire deforms. Therefore, the load applied to the RF tag when the tire deforms can be reduced. This improves the durability of the RF tag. The nylon chafer may, for example, have a portion adjacent to the rubber chafer on the outer side in the tire width direction. In this case, the RF tag may be disposed sandwiched between the nylon chafer and the rubber chafer. The nylon chafer may, for example, have a portion adjacent to the side rubber on the outer side in the tire width direction. In this case, the RF tag may be disposed sandwiched between the nylon chafer and the side rubber. The nylon chafer may, for example, have a portion adjacent to the stiffener on the inner side in the tire width direction. In this case, the RF tag may be disposed sandwiched between the nylon chafer and the stiffener. Furthermore, the nylon chafer may have a portion adjacent to the hat rubber, for example, on the inner side in the tire width direction. In such a case, the RF tag may be disposed by being sandwiched between the nylon chafer and the hat rubber. Furthermore, the nylon chafer may have a portion adjacent to the carcass, for example, on the inner side in the tire width direction. In such a case, the RF tag may be disposed by being sandwiched between the nylon chafer and the carcass. Furthermore, the nylon chafer may have a portion adjacent to the wire chafer, for example, on the inner side in the tire width direction. In such a case, the RF tag may be disposed by being sandwiched between the nylon chafer and the wire chafer. In this way, the RF tag may be disposed by being sandwiched between the nylon chafer and another member adjacent to the nylon chafer on the outer or inner side in the tire width direction. In particular, by covering the outer side of the RF tag in the tire width direction with the nylon chafer, the load applied to the RF tag due to impact or damage from the outside of the tire in the tire width direction can be further reduced. Therefore, the durability of the RF tag can be further improved.

[0034] The RF tag may be sandwiched between the wire chafer and another adjacent member on the inner or outer side of the wire chafer in the tire width direction. This makes it difficult for the position of the RF tag to fluctuate when the tire deforms. Therefore, the load applied to the RF tag when the tire deforms can be reduced. This improves the durability of the RF tag. The other adjacent member on the inner or outer side of the wire chafer in the tire width direction may be, for example, a rubber member such as a rubber chafer. Furthermore, the other adjacent member on the inner or outer side of the wire chafer in the tire width direction may be, for example, a carcass.

[0035] Example 1 In order to simulate the behavior of a tire breaking due to a protrusion, a simulation was carried out using a piece of rubber on which a cord was laid. Figure 4 shows the tensile force applied to the cord up to a certain displacement pressing against the protrusion when the size of the rubber piece is constant and the fiber length (and therefore the number of divisions and cord length) is variously changed (smaller numerical values ​​mean smaller tensile force; in other words, shorter cords have smaller tensile force when the same displacement is applied, making them less likely to break and providing a superior protective layer function).

[0036] Example 2: Truck and bus tires with a tire size of 275 / 80R22.5, each with various ratios of the belt reinforcement layer's division width to the tire width direction (a conventional example and four other examples), were mounted on a rim with a rim size of 22.5 x 8.25J and inflated to an internal pressure of 900 kPa. Then, using a blade with a blade length of 46 mm and a blade tip angle of 60°, the tire was pressed radially with the blade length aligned with the axis of rotation until the tire broke. The tire break energy evaluation results (expressed as an index with the conventional example being 1.00, with larger values ​​indicating greater tire break energy) are shown in Table 1 and Figure 7. The tire break energy was calculated by approximating the load at the time of break by the product of the radial displacement from the point where the blade contacted the tire to the break position, and 1 / 2.

[0037]

[0038] As shown in Table 1, it can be seen that the tire breaking energy in all of Comparative Examples 1 to 4 is larger than that of the conventional example.

[0039] As shown in FIG. 7, it can be seen that by dividing the belt reinforcing layer at one or more locations, a larger tire breaking energy is required compared to the conventional example.

[0040] The heavy-duty tire of the present disclosure is particularly suitable for truck and bus tires, and can also be used for extra-large tires such as tires for construction vehicles.

[0041] 1: tread portion, 2: belt, 3: belt reinforcing layer, 4: rubber block, 5: fiber, 6: protrusion

Claims

1. A heavy-duty tire having a tread portion including a belt consisting of one or more belt layers, and one or more belt reinforcing layers arranged radially outward of the belt, wherein the belt reinforcing layer is made of rubber-coated reinforcing cords, each of the reinforcing cords extends from one end of the belt reinforcing layer to the other end and is cut at the one end and the other end, each of the reinforcing cords is further divided at one or more locations between the one end and the other end, and the division positions of the reinforcing cords are located on the same straight line across a plurality of the reinforcing cords.

2. The heavy-load tire according to claim 1, wherein, in a cross-sectional view in the tire width direction, a sum of the cross-sectional areas of the plurality of reinforcing cords with respect to a cross-sectional area of ​​the belt reinforcing layer is equal to or greater than a sum of the cross-sectional areas of the plurality of belt cords of an outermost belt layer that is located outermost in the tire radial direction among the one or more belt layers with respect to a cross-sectional area of ​​the outermost belt layer.

3. A heavy-duty tire according to claim 1 or 2, wherein the division positions of each of the reinforcing cords are at the same positions in the tire width direction when viewed in the tire circumferential direction.

4. A heavy-duty tire according to any one of claims 1 to 3, wherein each of the divided reinforcing cords has a width in the tire width direction that is 6.25 to 50% of the width in the tire width direction of the belt reinforcing layer.

5. A heavy-duty tire according to any one of claims 1 to 4, wherein the divided surfaces of each of the divided reinforcing cords are in at least partial contact with each other.

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