Tire

Abstract

To satisfy both low fuel consumption performance and durability performance.SOLUTION: A belt layer 14 includes: an inner diameter side cross belt 141 having a belt cord of a belt angle of 45 [deg] or more in terms of absolute values with respect to a tire circumferential direction; an outer diameter side cross belt 143 disposed outside in a tire dimeter direction of the inner diameter side cross belt by having the belt cord of a belt angle of 45 [deg] or less in terms of absolute values with respect to the tire circumferential direction in a code different from the inner diameter side cross belt; and a circumferential reinforcement layer 142 having the belt cord of a belt angle within a range of ±5 [deg] with respect to the tire circumferential direction and disposed between the inner diameter side cross belt and the outer side cross belt, wherein a width W1 of the circumferential reinforcement layer in a tire width direction, a width W2 of the inner side cross belt in the tire width direction, and a width W3 of the outer diameter side cross belt in the tire width direction satisfy a relation of W1<W3<2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a tire.

Background Art

[0002] For example, Patent Document 1 describes a heavy-duty tire that suppresses shoulder edge wear while maintaining plunger durability. This heavy-duty tire includes a first belt layer composed of cords extending obliquely at an angle greater than 45° with respect to the tire circumferential direction, a second belt layer composed of cords extending in the tire circumferential direction, and a third belt layer composed of cords extending obliquely at an angle of 30° or less in the direction opposite to the cords of the first belt layer with respect to the tire circumferential direction. These are sequentially arranged from the inner side in the tire radial direction. The width w3 of the third belt layer is set to be 80% or more of the tread width w, and when the width of the first belt layer is w1 and the width of the second belt layer is w2, w2 < w1 < w3.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in order to promote fuel efficiency improvement due to recent environmental regulations, reduction of rolling resistance is required. Therefore, it is conceivable to reduce rolling resistance from the belt structure of the tire, but there is a concern about a decrease in durability.

[0005] An object of this invention is to provide a tire capable of achieving both low fuel consumption performance and durable performance with a belt structure.

Means for Solving the Problems

[0006] In order to achieve the above object, a tire according to an aspect of the present invention includes a carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer and continuous in the tire circumferential direction, a tread rubber disposed on the outer side in the tire radial direction of the belt layer, at least two circumferential main grooves extending in the tire circumferential direction in the tread rubber, and a plurality of land portions partitioned by the circumferential main grooves in the tread rubber. The belt layer includes an inner diameter side intersecting belt having a belt cord with a belt angle of 45° or more in absolute value with respect to the tire circumferential direction, an outer diameter side intersecting belt disposed on the outer side in the tire radial direction of the inner diameter side intersecting belt and having a belt cord with a belt angle of 45° or less in absolute value with respect to the tire circumferential direction and having a sign opposite to that of the inner diameter side intersecting belt, and a circumferential reinforcing layer having a belt cord with a belt angle within a range of ±5° with respect to the tire circumferential direction and disposed between the inner diameter side intersecting belt and the outer diameter side intersecting belt. A width W1 of the circumferential reinforcing layer, a width W2 of the inner diameter side intersecting belt, and a width W3 of the outer diameter side intersecting belt satisfy the relationship of W1 < W3 < W2.

Advantages of the Invention

[0007] According to this invention, it is possible to achieve both low fuel consumption performance and durability performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by these embodiments. Also, the components of this embodiment include those that are replaceable and self-evidently replaceable while maintaining the identity of the invention. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope self-evident to those skilled in the art.

[0010] In the following description, the tire radial direction refers to a direction orthogonal to the tire rotation axis (not shown) which is the rotation axis of the pneumatic tire 1 of the embodiment, the inner side in the tire radial direction refers to the side facing the tire rotation axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the tire rotation axis in the tire radial direction. Further, the tire circumferential direction refers to the circumferential direction around the tire rotation axis as the central axis. Also, the tire width direction refers to a direction parallel to the tire rotation axis, the inner side in the tire width direction refers to the side facing the tire equatorial plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction refers to the side away from the tire equatorial plane CL in the tire width direction. The tire equatorial plane CL is a plane that is orthogonal to the tire rotation axis and passes through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL coincides with the center line in the tire width direction which is the central position in the tire width direction of the pneumatic tire 1. The tire equator line refers to a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic tire 1. Also, the cross-section in the tire meridian direction (meridian cross-sectional view) refers to the cross-section when the tire is cut by a plane including the tire rotation axis.

[0011] FIG. 1 shows a meridian cross-section of the pneumatic tire 1 of the embodiment, showing a cross-section of one side region of the tire rotation axis in the tire radial direction. In the present embodiment, as an example, a heavy-duty pneumatic radial tire mounted on a heavy-duty vehicle such as a truck or a bus will be described. The pneumatic tire 1 of the present embodiment is particularly suitable for all-season tires.

[0012] The pneumatic tire 1 of the embodiment has an annular structure centered on the tire rotation axis. Although not shown in the figure, it includes a pair of bead cores, a pair of bead fillers, a pair of rim cushion rubbers, a carcass layer 13 shown in FIG. 1, a belt layer 14, a tread rubber 15, and a pair of sidewall rubbers 16, 16.

[0013] The pair of bead cores are formed by winding one or more bead wires made of steel in an annular and multiple manner, and are embedded in the bead portion to form the cores of the bead portions on both sides in the tire width direction. The pair of bead fillers are respectively arranged on the outer side in the tire radial direction of the pair of bead cores to reinforce the bead portion. The pair of rim cushion rubbers extend from the inner side in the tire radial direction of each bead core and the turned-back portion of the carcass layer 13 to the outer side in the tire width direction to form the rim fitting surface of the bead portion.

[0014] The carcass layer 13 has a single-layer structure composed of one carcass ply or a multi-layer structure formed by laminating a plurality of carcass plies. The carcass layer 13 is bridged in a toroidal shape between the two bead cores to form the skeleton of the tire. Also, both ends of the carcass layer 13 are turned back and locked to the outer side in the tire width direction so as to wrap the bead cores and the bead fillers. Further, the carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel with a coating rubber and performing rolling processing. In the case of a radial tire, it has a cord angle (defined as the inclination angle of the longitudinal direction of the carcass cord with respect to the tire circumferential direction) of 80° or more and 100° or less in absolute value, and in the case of a bias tire, it has a cord angle of 30° or more and 45° or less.

[0015] The belt layer 14 is formed by laminating at least three belt plies 141 to 143, and is wound around the outer periphery of the carcass layer 13 and continuously arranged in the tire circumferential direction. These belt plies 141 to 143 include an inner diameter side cross belt 141, an outer diameter side cross belt 143, and a circumferential direction reinforcing layer 142.

[0016] The inner-diameter side cross belt 141 is arranged on the inner side in the tire diameter direction among the three belt plies. As shown in FIG. 2, the inner-diameter side cross belt 141 is formed by covering a plurality of belt cords 141a made of steel with a cover rubber 141b and performing rolling processing. In the inner-diameter side cross belt 141, the belt cords 141a have a belt angle θ2 with an absolute value of 45° or more with respect to the tire circumferential direction.

[0017] The outer-diameter side cross belt 143 is arranged on the outer side in the tire diameter direction among the three belt plies. As shown in FIG. 2, the outer-diameter side cross belt 143 is formed by covering a plurality of belt cords 143a made of steel with a cover rubber 143b and performing rolling processing. In the outer-diameter side cross belt 143, the belt cords 143a have a belt angle θ1 with an absolute value of 45° or less with respect to the tire circumferential direction and having a sign opposite to that of the inner-diameter side cross belt 141.

[0018] The circumferential direction reinforcing layer 142 is arranged between the inner-diameter side cross belt 141 and the outer-diameter side cross belt 143 among the three belt plies. As shown in FIG. 2, the circumferential direction reinforcing layer 142 is formed by covering a plurality of belt cords 142a made of steel with a cover rubber 142b and performing rolling processing. In the circumferential direction reinforcing layer 142, the belt cords 142a have a belt angle within a range of ±5° with an absolute value with respect to the tire circumferential direction.

[0019] As shown in FIG. 1, the tread rubber 15 is disposed on the outer side in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute the tread portion of the pneumatic tire 1. The tread rubber 15 has a tread surface (tread running surface) 15A on the outer peripheral surface that contacts the road surface during running. The outer end of the tread surface 15A in the tire width direction serves as the grounding end T. Further, the tread rubber 15 has buttress portions 15B on both outer side portions in the tire width direction that do not contact the road surface during running, which are located outside the grounding end T of the tread surface 15A. The buttress portions 15B are provided in the tread rubber 15 from the grounding end T outward in the tire width direction and inward in the tire radial direction up to the sidewall rubber 16. The buttress portions 15B are formed in a trapezoidal shape with a larger dimension in the tire width direction from the outer side in the tire radial direction to the inner side in the tire radial direction.

[0020] The grounding end T is defined as the maximum width position in the tire axial direction on the contact surface between the tire and the flat plate when the tire is placed perpendicular to the flat plate in a stationary state under a load corresponding to the specified load with the tire mounted on the specified rim and filled with the specified internal pressure (inflated state).

[0021] The specified rim refers to the "Standard Rim" specified by JATMA, the "Design Rim" specified by TRA, or the "MEASURING RIM" specified by ETRTO. Also, the specified internal pressure refers to the "Maximum Air Pressure" specified by JATMA, the maximum value of the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO. The specified load refers to the "Maximum Load Capacity" specified by JATMA, the maximum value of the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO. In the case of the pneumatic tire 1 of the embodiment, the specified load is 88[%] of the maximum load capacity at the specified internal pressure.

[0022] A pair of sidewall rubbers 16, 16 are respectively arranged on the outer sides in the tire width direction of the carcass layer 13 to constitute sidewall portions on both sides in the tire width direction.

[0023] As shown in FIG. 1, the pneumatic tire 1 of the embodiment includes a circumferential main groove 21 extending along the tire circumferential direction and a plurality of land portions 31 defined by the circumferential main groove 21 on the tread surface 15A.

[0024] The circumferential main groove 21 extends along the tire circumferential direction and has an annular structure that extends linearly and continuously over the entire tire circumference. The circumferential main groove 21 is defined as a groove having the display obligation of a wear indicator defined by JATMA. The circumferential main groove 21 has a groove width of 5 [mm] or more and 20 [mm] or less, and a groove depth of 7 [mm] or more and 30 [mm] or less.

[0025] The groove width is measured as the maximum value of the distance between opposing groove walls or edges at the opening edge portion on the tread surface 15A in a no-load state where the tire is mounted on a specified rim and filled with a specified internal pressure.

[0026] The groove depth is measured as the maximum value of the distance from the tread surface 15A to the groove bottom in a no-load state where the tire is mounted on a specified rim and filled with a specified internal pressure. Also, in a configuration having partial uneven portions or sipes at the groove bottom, the groove depth is measured excluding these.

[0027] In the pneumatic tire 1 of the embodiment, as shown in FIG. 3, the circumferential main groove 21 has one disposed within the range of the center region CE on the tread surface 15A and one disposed within the range of the shoulder region SE on the tread surface 15A. In the embodiment, one circumferential main groove 21 is disposed in each center region CE with the tire equatorial plane CL as a boundary, and one circumferential main groove 21 is disposed in each shoulder region SE with the tire equatorial plane CL as a boundary.

[0028] The center region CE is an area within a range of 1 / 4 from the tire equatorial plane CL to both outer sides in the tire width direction with respect to the tread width Wt of the tread surface 15A between both grounding ends T (measurement dimension in the unloaded state where the tire is mounted on a specified rim and filled with a specified internal pressure). The shoulder region SE is an area within a range of 1 / 4 from each grounding end T to the inner side in the tire width direction with respect to the tread width Wt of the tread surface 15A between both grounding ends T (measurement dimension in the unloaded state where the tire is mounted on a specified rim and filled with a specified internal pressure).

[0029] The land portion 31 extends over the entire circumference of the tire and constitutes an annular tread surface (ground contact surface). The land portion 31 includes a center land portion disposed in the center region CE, a middle land portion straddling the center region CE and the shoulder region SE, and a shoulder land portion at the outermost side in the tire width direction disposed in the shoulder region SE.

[0030] The pneumatic tire 1 of the embodiment is configured such that one side and the other side on the outer side in the tire width direction are symmetric with respect to the tire equatorial plane CL as a boundary.

[0031] The pneumatic tire 1 of the embodiment is characterized by including a carcass layer 13, a belt layer 14 disposed on the outer side in the tire radial direction of the carcass layer 13 and continuous in the tire circumferential direction, a tread rubber 15 disposed on the outer side in the tire radial direction of the belt layer 14, at least two circumferential main grooves 21 extending in the tire circumferential direction in the tread rubber 15, and a plurality of land portions 31 partitioned by the circumferential main grooves 21 in the tread rubber 15. The belt layer 14 includes an inner diameter side intersecting belt 141 having a belt cord 141a with a belt angle of 45° or more in absolute value with respect to the tire circumferential direction, an outer diameter side intersecting belt 143 disposed on the outer side in the tire radial direction of the inner diameter side intersecting belt 141 and having a belt cord 143a with a belt angle of 45° or less in absolute value and opposite in sign to the inner diameter side intersecting belt 141 with respect to the tire circumferential direction, and a circumferential reinforcing layer 142 having a belt cord 142a with a belt angle within a range of ±5° with respect to the tire circumferential direction and disposed between the inner diameter side intersecting belt 141 and the outer diameter side intersecting belt 143. As shown in FIG. 1, the width W1 in the tire width direction of the circumferential reinforcing layer 142, the width W2 in the tire width direction of the inner diameter side intersecting belt 141, and the width W3 in the tire width direction of the outer diameter side intersecting belt 143 satisfy the relationship of W1 < W3 < W2.

[0032] According to this pneumatic tire 1, the inner diameter side cross belt 141 functions as a belt ply having belt cords 141a at a relatively high angle, ensuring rigidity in the tire width direction. Also, according to this pneumatic tire 1, the circumferential reinforcing layer 142 and the outer diameter side cross belt 143 function as belt plies having belt cords 142a, 143a at a relatively low angle, ensuring rigidity in the tire circumferential direction. As a result, in this pneumatic tire 1, the rigidity balance between the tire width direction and the tire circumferential direction is optimized, rolling resistance is reduced, and the low fuel consumption performance of the pneumatic tire 1 is improved. Moreover, by satisfying the relationship of W1 < W3 < W2, in the inner diameter side cross belt 141 and the outer diameter side cross belt 143 arranged as cross belts, the width W2 of the inner diameter side cross belt 141 is larger than the width W3 of the outer diameter side cross belt 143, and a sufficient rubber layer can be secured according to the trapezoidal outer shell profile of the buttress portion 15B. Therefore, in terms of the tire width direction dimension along it, the tire durability performance is improved from the perspective of belt separation.

[0033] Also, in the pneumatic tire 1 of the embodiment, the circumferential main groove 21 exists in the center region CE of the tread surface 15A. As shown in FIG. 3, an additional belt 144 is provided on the outer side in the tire radial direction of the outer diameter side cross belt 143. The range of the width W4 of the additional belt 144 in the tire width direction includes the position of the circumferential main groove 21 in the center region CE and is less than 90[%] with respect to the width W3 of the outer diameter side cross belt 143.

[0034] The additional belt 144 is arranged on the outer side in the tire radial direction of the outer diameter side cross belt 143 in addition to the above three belt plies of the belt layer 14. The additional belt 144 is formed by covering a plurality of belt cords made of steel with cover rubber and performing rolling processing. The belt cords of the additional belt 144 have a belt angle with the same sign as the outer diameter side cross belt 143 and an absolute value of 20 [deg] (including 10 [deg] or more and 45 [deg] or less) with respect to the tire circumferential direction.

[0035] During the running process, there is an event where a stone that has entered the groove bottom digs into the groove bottom of the circumferential main groove 21, damages the outer diameter side cross belt 143, and accelerates the deterioration of the tire structure. In particular, the event of a stone entering the groove bottom of the circumferential main groove 21 frequently occurs in the circumferential main groove 21 in the center region CE. In this regard, according to this pneumatic tire 1, by arranging the additional belt 144 on the outer side in the tire radial direction of the outer diameter side cross belt 143 within the range of the center region CE, the outer diameter side cross belt 143 can be protected from the above event.

[0036] Further, in the pneumatic tire 1 of the embodiment, in the unloaded state where the tire is mounted on a specified rim and filled with a specified internal pressure, the width W1 of the circumferential reinforcing layer 142 is 50[%] or more and 70[%] or less with respect to the cross-sectional width Wp of the carcass layer 13.

[0037] The cross-sectional width Wp of the carcass layer 13 is the largest cross-sectional dimension in the tire width direction of the carcass cords excluding the coat rubber of the carcass layer 13, and is the dimension between both outermost sides in the tire width direction of the carcass cords.

[0038] According to this pneumatic tire 1, by setting the width W1 of the circumferential reinforcing layer 142 within the above range, the internal pressure sharing between the belt layer 14 and the carcass layer 13 in the inflated state can be set in a well-balanced manner, and the overall tire durability performance is improved.

[0039] Further, in the pneumatic tire 1 of the embodiment, the width W1 of the circumferential reinforcing layer 142 is 65[%] or more and 80[%] or less with respect to the width W2 of the inner diameter side cross belt 141, and the difference between the width W2 of the inner diameter side cross belt 141 and the width W3 of the outer diameter side cross belt 143 is 30 [mm] or less.

[0040] According to this pneumatic tire 1, by setting the width W1 of the circumferential reinforcing layer 142 within the above range, it is effective in increasing the rigidity in the tire circumferential direction. Also, according to this pneumatic tire 1, by setting the difference between the width W2 of the inner diameter side intersecting belt 141 and the width W3 of the outer diameter side intersecting belt 143 within the above range, a sufficient rubber layer can be secured in the tire radial direction at the end of the intersecting belt composed of the inner diameter side intersecting belt 141 and the outer diameter side intersecting belt 143, and the difference in the width of the intersecting belt can be reduced. Therefore, the tag effect range of the intersecting belt can be widened, and the tire durability performance is further improved.

[0041] Also, in the pneumatic tire 1 of the embodiment, the outer diameter side intersecting belt 143 is arranged adjacent to the tread rubber 15. That is, there is no belt having a belt cord (for example, additional belt 144) between the outer diameter side intersecting belt 143 and the tread rubber 15 on the outer side in the tire radial direction.

[0042] In the structure of a general heavy-duty tire, a low-angle belt having a belt cord at a relatively low angle with respect to the tire circumferential direction is arranged as a protective layer on the outer side in the tire radial direction of the intersecting belt. In this regard, according to this pneumatic tire 1, by having the circumferential reinforcing layer 142 with a belt cord close to 0[deg], the rigidity in the tire circumferential direction is ensured, so the low-angle belt becomes unnecessary, and the low fuel consumption performance is improved from the viewpoint of weight reduction.

[0043] Also, in the pneumatic tire 1 of the embodiment, the inner diameter side intersecting belt 141 is arranged adjacent to the carcass layer 13. That is, there is no belt having a belt cord between the inner diameter side intersecting belt 141 and the carcass layer 13 on the inner side in the tire radial direction.

[0044] In the structure of a general heavy-duty tire, as shown in FIG. 4, a high-angle belt 140 having a belt cord at a relatively high angle with respect to the tire circumferential direction (for example, with the same reference numeral as the inner-diameter-side intersecting belt 141, an absolute value of 45° or more and 70° or less with respect to the tire circumferential direction) is disposed on the inner side in the tire radial direction of the intersecting belt composed of the inner-diameter-side intersecting belt 141 and the outer-diameter-side intersecting belt 143 so as to ensure the rigidity in the tire width direction. In this regard, according to this pneumatic tire 1, the outer-diameter-side intersecting belt 143 on the outer side in the tire radial direction of the intersecting belt functions as a high-angle belt, so that the rigidity in the tire width direction is ensured, and at the same time, since the high-angle belt 140 is unnecessary, the low fuel consumption performance is improved from the viewpoint of weight reduction.

[0045] Further, in the pneumatic tire 1 of the embodiment, the circumferential main grooves 21 are present in the center region CE and the shoulder region SE of the tread surface 15A, and as shown in FIG. 1, the distance D from the circumferential main groove 21 in the center region CE to the belt layer 14 and the distance d from the circumferential main groove 21 in the shoulder region SE to the belt layer 14 satisfy the relationship of 0.8 < D / d < 1.3.

[0046] According to this pneumatic tire 1, by making the distance from the bottom of the circumferential main groove 21 to the belt cord of the belt layer 14 equal at the positions of the circumferential main grooves 21 in the center region CE and the shoulder region SE, the strain difference in the tire width direction of the tread surface 15A is reduced, and the ground contact partial pressure is equalized, so that a further improvement in low fuel consumption performance can be expected.

[0047] Further, in the pneumatic tire 1 of the embodiment, the tread width Wt of the tread surface 15A is 60% or more and 95% or less with respect to the cross-sectional width Wp of the carcass layer 13.

[0048] According to this pneumatic tire 1, by setting as described above, it is possible to maintain an appropriate balance in the internal pressure sharing ratio of the carcass layer 13 in the shoulder region SE in the inflated state, and an improvement in the overall durability performance of the tire can be expected in terms of reducing the distortion during deflection at the time of grounding. In the pneumatic tire 1 of the embodiment, in the range where low rolling resistance can be confirmed, 75[%] ≦ Wt / Wp ≦ 80[%] is preferable. Further, in the case of the ultra-low-profile pneumatic tire 1 with a tread width Wt of 450 [mm] or more, 75[%] ≦ Wt / Wp ≦ 85[%] is preferable.

[0049] Further, in the pneumatic tire 1 of the embodiment, the belt layer 14 is composed of three belt plies: an inner diameter side cross belt 141, an outer diameter side cross belt 143, and a circumferential reinforcing layer 142.

[0050] According to this pneumatic tire 1, further improvement in low fuel consumption performance can be expected due to weight reduction by reducing the number of belts.

[0051] Further, in the pneumatic tire 1 of the embodiment, the tread width Wt of the tread surface 15A is 300 [mm] or less.

[0052] Generally, a tire having a circumferential reinforcing layer 142 is often applied to a low-profile tire or a tire with a tread width Wt exceeding 300 [mm] called a wide base. In this regard, this pneumatic tire 1 can also be applied to a general-purpose size with a tread width Wt of 300 [mm] or less that has improved durability performance and improved low fuel consumption performance. In the pneumatic tire 1 of the embodiment, preferably, the tread width Wt of the tread surface 15A is 250 [mm] or less.

[0053] Incidentally, in the present embodiment, as described above, the pneumatic tire 1 has been described as an example of a tire. This pneumatic tire 1 can be filled with air, an inert gas such as nitrogen, and other gases. However, the configuration of the tread pattern of the pneumatic tire 1 described in the present embodiment can be arbitrarily applied to other tires within the scope obvious to those skilled in the art. Examples of other tires include airless tires and solid tires.

Example

[0054] Figs. 5 and 6 are charts showing the results of the performance tests of the pneumatic tire according to the embodiment. Hereinafter, the performance evaluation tests conducted on the conventional pneumatic tire, the comparative pneumatic tire, and the pneumatic tire of the example according to the embodiment will be described. The performance evaluation tests were tests on low fuel consumption performance and durability performance.

[0055] For the evaluation test of the low rolling resistance performance, a pneumatic tire of tire size 275 / 80R22.5 (tire size 445 / 50R22.5 for Example 10) was assembled on a standard rim specified by JATMA, and the internal pressure specified by JATMA was applied. Then, a drum tester with a drum diameter of 1707 [mm] was used, and the reciprocal of the rolling resistance coefficient of the test tire was calculated and evaluated under the condition of a speed of 80 [km / h] in accordance with ISO28580. This evaluation is performed by index evaluation with the conventional example as the reference (100), and the larger the numerical value, the better the low rolling resistance performance.

[0056] For the durability performance evaluation test, an inflated tire with a tire size of 275 / 80R22.5 (tire size 445 / 50R22.5 for Example 10) was assembled onto a standard rim specified by JATMA, and the internal pressure specified by JATMA was applied. Then, a drum tester with a camber and a drum diameter of 1707 [mm] was used, the speed was set to 81 km / h, and the load was continuously increased in 15 steps from the specified load to a maximum of 270% in increments of 13% each. The running time until failure occurred was measured, and the reciprocal was calculated and evaluated. This evaluation was performed by index evaluation with the conventional example as the reference (100), and the larger the numerical value, the better the load durability performance.

[0057] The conventional inflated tire includes an inner diameter side cross belt, an outer diameter side cross belt, and a circumferential reinforcing layer in the belt layer, and the relationship of the widths W1, W2, and W3 satisfies the regulations, but the angle of the belt cord of the inner diameter side cross belt does not satisfy the regulations.

[0058] The inflated tire of Comparative Example 1 does not include a circumferential reinforcing layer in the belt layer. The inflated tire of Comparative Example 2 includes an inner diameter side cross belt, an outer diameter side cross belt, and a circumferential reinforcing layer in the belt layer, and the relationship of the widths W1, W2, and W3 satisfies the regulations, but the angle of the belt cord of the outer diameter side cross belt does not satisfy the regulations. The inflated tire of Comparative Example 3 includes an inner diameter side cross belt, an outer diameter side cross belt, and a circumferential reinforcing layer in the belt layer, and the angles of the belt cords of the outer diameter side cross belt and the inner diameter side cross belt satisfy the regulations, but the relationship of the widths W1, W2, and W3 does not satisfy the regulations.

[0059] The inflated tire of the example includes an inner diameter side cross belt, an outer diameter side cross belt, and a circumferential reinforcing layer in the belt layer, and the angles of the belt cords of the outer diameter side cross belt and the inner diameter side cross belt, and the relationship of the widths W1, W2, and W3 satisfy the regulations.

[0060] And as shown in the test results, it can be seen that the inflated tire of this example has improved low rolling resistance performance and durability performance compared to the conventional example.

[0061] The present disclosure includes the following inventions. [Invention 1] A carcass layer, A belt layer disposed on the outer side in the tire radial direction of the carcass layer and continuous in the tire circumferential direction, Tread rubber disposed on the outer side in the tire radial direction of the belt layer, At least two circumferential main grooves extending in the tire circumferential direction in the tread rubber, A plurality of land portions partitioned by the circumferential main grooves in the tread rubber, Comprising, The belt layer includes an inner diameter side intersecting belt having a belt cord with a belt angle of 45° or more in absolute value with respect to the tire circumferential direction, An outer diameter side intersecting belt having a belt cord with a belt angle of 45° or less in absolute value and opposite in sign to the inner diameter side intersecting belt, and disposed on the outer side in the tire radial direction of the inner diameter side intersecting belt, A circumferential reinforcing layer having a belt cord with a belt angle within a range of ±5° with respect to the tire circumferential direction and disposed between the inner diameter side intersecting belt and the outer diameter side intersecting belt, Including, The width W1 of the circumferential reinforcing layer, the width W2 of the inner diameter side intersecting belt, and the width W3 of the outer diameter side intersecting belt satisfy the relationship W1 < W3 < W2, Tire. [Invention 2] The width W1 of the circumferential reinforcing layer is 50% or more and 70% or less with respect to the cross-sectional width Wp of the carcass layer, The tire according to Invention 1. [Invention 3] The width W1 of the circumferential reinforcing layer is 65% or more and 80% or less with respect to the width W2 of the inner diameter side intersecting belt, The difference between the width W2 of the inner diameter side intersecting belt and the width W3 of the outer diameter side intersecting belt is 30 mm or less, The tire according to any one of Inventions 1 or 2. [Invention 4] The circumferential main grooves are present in the center region and the shoulder region of the tread surface, The distance D from the circumferential main groove in the center region to the belt layer and the distance d from the circumferential main groove in the shoulder region to the belt layer satisfy the relationship 0.8 < D / d < 1.3. The tire according to any one of Inventions 1 to 3. [Invention 5] The tread width Wt of the tread surface is 60[%] or more and 95[%] or less with respect to the cross-sectional width Wp of the carcass layer. The tire according to any one of Inventions 1 to 4. [Invention 6] The inner diameter side cross belt is disposed adjacent to the carcass layer. The tire according to any one of Inventions 1 to 5. [Invention 7] The outer diameter side cross belt is disposed adjacent to the tread rubber. The tire according to any one of Inventions 1 to 6. [Invention 8] The belt layer is composed of three belt plies: the inner diameter side cross belt, the outer diameter side cross belt, and the circumferential reinforcing layer. The tire according to any one of Inventions 1 to 7. [Invention 9] The circumferential main groove is present in the center region of the tread surface. An additional belt is provided on the outer side in the tire radial direction of the outer diameter side cross belt. The range of the width W4 of the additional belt includes the position of the circumferential main groove in the center region and is less than 90[%] with respect to the width W3 of the outer diameter side cross belt. The tire according to any one of Inventions 1 to 6. [Invention 10] The tread width Wt of the tread surface is 300 [mm] or less. The tire according to any one of Inventions 1 to 9.

Explanation of Signs

[0062] 1 Pneumatic tire (tire) 13 Carcass layer 14 Belt layer 15 Tread rubber 15A Tread surface 21 Circumferential main groove 31 Land part 141 Inner diameter side cross belt 141a Belt cord 142 Circumferential reinforcement layer 142a Belt cord 143 Outer diameter side cross belt 143a Belt cord 144 Additional belt CE Center region SE Shoulder region

Claims

1. A carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer and continuous in the tire circumferential direction, tread rubber disposed on the outer side in the tire radial direction of the belt layer, at least two circumferential main grooves extending in the tire circumferential direction in the tread rubber, a plurality of land portions partitioned by the circumferential main grooves in the tread rubber, and comprising: the belt layer includes an inner diameter side intersecting belt having a belt cord with a belt angle of 45 [deg] or more in absolute value with respect to the tire circumferential direction, an outer diameter side intersecting belt having a belt cord with a belt angle of 45 [deg] or less in absolute value with respect to the tire circumferential direction and disposed on the outer side in the tire radial direction of the inner diameter side intersecting belt with a sign different from that of the inner diameter side intersecting belt, and a circumferential reinforcing layer having a belt cord with a belt angle within a range of ±5 [deg] with respect to the tire circumferential direction and disposed between the inner diameter side intersecting belt and the outer diameter side intersecting belt, wherein: a width W1 of the circumferential reinforcing layer, a width W2 of the inner diameter side intersecting belt, and a width W3 of the outer diameter side intersecting belt satisfy a relationship of W1 < W3 < W2, a tire.

2. the circumferential main grooves are present in a center region of the tread surface, an additional belt is provided on the outer side in the tire radial direction of the outer diameter side intersecting belt, a range of a width W4 of the additional belt includes a position of the circumferential main grooves in the center region and is less than 90 [%] with respect to the width W3 of the outer diameter side intersecting belt, the tire according to claim 1.

3. the width W1 of the circumferential reinforcing layer is 50 [%] or more and 70 [%] or less with respect to a cross-sectional width Wp of the carcass layer, the tire according to claim 1.

4. the width W1 of the circumferential reinforcing layer is 65 [%] or more and 80 [%] or less with respect to the width W2 of the inner diameter side intersecting belt, a difference between the width W2 of the inner diameter side intersecting belt and the width W3 of the outer diameter side intersecting belt is 30 [mm] or less, the tire according to claim 1.

5. the outer diameter side intersecting belt is disposed adjacent to the tread rubber, the tire according to claim 1.

6. the inner diameter side intersecting belt is disposed adjacent to the carcass layer, the tire according to claim 1.

7. the circumferential main grooves are present in a center region and a shoulder region of the tread surface, The distance D from the circumferential main groove in the center region to the belt layer and the distance d from the circumferential main groove in the shoulder region to the belt layer satisfy the relationship of 0.8 < D / d < 1.

3. The tire according to claim 1.

8. The tread width Wt of the tread surface is 60 [%] or more and 95 [%] or less with respect to the cross-sectional width Wp of the carcass layer. The tire according to claim 1.

9. The belt layer is composed of three belt plies, namely, the inner diameter side cross belt, the outer diameter side cross belt, and the circumferential reinforcing layer. The tire according to claim 1.

10. The tread width Wt of the tread surface is 300 [mm] or less. The tire according to claim 1.

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