tire

Abstract

To provide a tire which makes it possible to improve pin pull-out resistance without deteriorating road surface damage property.SOLUTION: In a tire including a hole 13 into which a stud pin 20 is inserted in a tread part 1, a flat part 14 exists around the hole 13, the flat part annularly continuous by coinciding with a profile line L of the tread part 1, and a convex part 15 protruded more than the flat part 14 and a concave part 16 recessed more than the flat part 14 are mixed within an annular region A when the annular region A around which a distance from a center O of the hole 13 is 4 mm-8 mm is regulated around the flat part 14.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a tire having holes in a tread portion into which stud pins are inserted, and more particularly to a tire capable of improving the pin retention property without deteriorating the road surface damage property.

Background Art

[0002] A stud tire has a large number of holes in a tread portion into which stud pins are inserted, and is used with the stud pins inserted into the respective holes (see, for example, Patent Documents 1 to 4).

[0003] The stud tire configured as described above belongs to the category having the best running performance on ice, and its high ice performance is, of course, brought about by the stud pins. On the other hand, in order to improve the road surface damage property regulated by regulations, the stud pins have been miniaturized year by year, and there is a concern that the pin retention property deteriorates more than before. The pin retention property is related to the product life, and can be said to be one of the most important problems of current stud tires.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a tire capable of improving the pin retention property without deteriorating the road surface damage property. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides a tire having holes in the tread portion into which stud pins are inserted, wherein a flat portion exists around the hole that is connected in an annular shape and coincides with the profile line of the tread portion, and when an annular region is defined around the flat portion at a distance of 4 mm to 8 mm from the center of the hole, the annular region contains a mixture of convex portions that are raised higher than the flat portion and concave portions that are recessed lower than the flat portion. Occasionally, The recesses are arranged on concentric circles centered on the hole, and the recesses have an intermittent shape in a part of the circumferential direction of the concentric circles. It is characterized by the following: [Effects of the Invention]

[0007] In this invention, a tire equipped with holes in the tread portion into which stud pins are inserted has a flat portion that is connected in an annular shape around the hole and coincides with the profile line of the tread portion, so that the stud pins can be held stably. Furthermore, when an annular region is defined around the flat portion at a distance of 4 mm to 8 mm from the center of the hole, the convex portion that is higher than the flat portion and the concave portion that is lower than the flat portion are mixed within this annular region, so when the stud pin collapses, the force acting in the direction of collapse is distributed based on the presence of the concave portion, preventing the stud pin from falling out. In this case, if the rigidity is extremely reduced due to the presence of the concave portion, the stud pin may collapse easily and the resistance to pin detachment may worsen, but the presence of convex portions along with concave portions within the annular region can compensate for the lack of rigidity. Therefore, the presence of both convex portions and concave portions within the annular region can effectively improve the resistance to pin detachment. In addition, the structure that distributes the force when the stud pin collapses, as described above, also has the effect of improving road surface damage by reducing the force with which the stud pin attacks the road surface when driving on a dry road surface. Therefore, according to the present invention, it is possible to improve pin detachment resistance without worsening road surface damage.

[0008] In the present invention, it is preferable that the recesses are arranged on concentric circles centered on the hole, and that the recesses have an intermittent shape in a part of the circumferential direction of the concentric circles. If the recesses are continuous in the circumferential direction of the concentric circles centered on the hole, the stud pins will be prone to collapsing due to insufficient rigidity, which is disadvantageous in terms of resistance to pin detachment. However, by having an intermittent shape in a part of the circumferential direction of the concentric circles, rigidity around the stud pins can be ensured, and the stud pins can be prevented from falling out.

[0009] Preferably, the recess is positioned so as not to overlap with the circumferential line that passes through the center of the hole and is parallel to the tire's circumferential direction. This suppresses excessive tilting of the stud pin during rapid acceleration and deceleration, effectively preventing the stud pin from falling out.

[0010] Preferably, the recess is positioned so as not to overlap with a widthwise line that passes through the center of the hole and is perpendicular to the tire's circumferential direction. This suppresses excessive tilting of the stud pin during sharp turns and effectively prevents the stud pin from falling out.

[0011] When an inner annular region is defined within the annular region where the distance from the center of the hole is 4 mm to 6 mm, and an outer annular region where the distance from the center of the hole is 6 mm to 8 mm, it is preferable that the area of ​​the recess included in the inner annular region is larger than the area of ​​the recess included in the outer annular region. This effectively disperses the force generated when a strong force is applied to the stud pin, thereby improving the pin's resistance to coming loose.

[0012] It is preferable that the recesses are arranged on multiple concentric circles centered on the hole. This effectively distributes the force acting in the direction of the stud pin's collapse when it collapses, preventing the stud pin from falling out. In this case, it is preferable that the recesses on the multiple concentric circles overlap each other in the radial direction of the concentric circles. This effectively distributes the force acting in the direction of the stud pin's collapse when it collapses, preventing the stud pin from falling out, while also greatly improving the road surface damage resistance. Alternatively, it is preferable that the recesses on the multiple concentric circles do not overlap each other in the radial direction of the concentric circles. This effectively distributes the force acting in the direction of the stud pin's collapse when it collapses, while also ensuring rigidity to prevent excessive collapse of the stud pin, thus greatly improving the pin's resistance to coming loose.

[0013] When the body portion of a stud pin inserted into a hole has a longitudinal direction in a plan view of the tread portion, and when an inner annular region is defined within the annular region at a distance of 4 mm to 6 mm from the center of the hole and an outer annular region at a distance of 6 mm to 8 mm from the center of the hole, it is preferable that the recess is positioned within the inner annular region at a location that does not coincide with a virtual line passing through the center of the hole and parallel to the longitudinal direction of the body portion. If the distance between the body portion of the stud pin and the recess is too close, the pin's resistance to coming loose may deteriorate due to insufficient rigidity. However, by positioning the recess within the inner annular region at a location that does not coincide with a virtual line passing through the center of the hole and parallel to the longitudinal direction of the body portion, the pin's resistance to coming loose can be effectively improved.

[0014] Preferably, the depth Hy of the recess satisfies the relationship 0.05Hs ≤ Hy ≤ 0.25Hs with respect to the height Hs of the stud pin, and the height Hx of the protrusion satisfies the relationship 0.10Hy ≤ Hx ≤ 0.80Hy with respect to the depth Hy of the recess. This effectively improves the resistance to pin detachment.

[0015] The tire of the present invention is preferably a pneumatic tire, but may also be a non-pneumatic tire. In the case of a pneumatic tire, it can be filled with air, an inert gas such as nitrogen, or other gases inside.

Brief Description of the Drawings

[0016] [Figure 1] It is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view showing the stud pin installation part in the tread part of the pneumatic tire of FIG. 1. [Figure 3] It is a plan view showing the stud pin installation part in the tread part of the pneumatic tire of FIG. 1. [Figure 4] It is a perspective view showing an example of a stud pin. [Figure 5] It is a plan view showing the stud pin of FIG. 4. [Figure 6] It is a side view showing the stud pin of FIG. 4. [Figure 7] It is a cross-sectional view showing a state where the stud pin of FIG. 4 is inserted into the hole in the tread part. [Figure 8] (a) to (c) are each plan views showing modified examples of the stud pin installation part [however, FIG. 8(a) is a reference example]. [Figure 9] (a) to (d) are each plan views showing other modified examples of the stud pin installation part. [Figure 10] It is a plan view showing still another modified example of the stud pin installation part. [Figure 11] (a) to (e) are each plan views showing still another modified example of the stud pin installation part [however, FIGS. 11(a) and (b) are reference examples]. [Figure 12] It is a plan view showing still another modified example of the stud pin installation part.

Embodiments for Carrying Out the Invention

[0017] The configuration of the present invention will be described in detail below with reference to the attached drawings. Figure 1 shows a pneumatic tire according to an embodiment of the present invention, Figures 2 and 3 show the stud pin installation portion in the tread portion, Figures 4 to 6 show an example of a stud pin, and Figure 7 shows the state in which the stud pin is inserted into the hole in the tread portion.

[0018] As shown in Figure 1, the pneumatic tire of this embodiment comprises a tread portion 1 that extends in the circumferential direction of the tire and forms an annular shape, a pair of sidewall portions 2, 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3, 3 arranged radially inward of these sidewall portions 2.

[0019] A carcass layer 4 is mounted between a pair of bead sections 3, 3. This carcass layer 4 includes multiple reinforcing cords extending in the radial direction of the tire, which are folded back from the inside to the outside of the tire around the bead core 5 located in each bead section 3. A bead filler 6 made of a rubber composition with a triangular cross-section is placed on the outer circumference of the bead core 5.

[0020] On the other hand, multiple belt layers 7 are embedded on the outer circumference of the carcass layer 4 in the tread portion 1. These belt layers 7 include multiple reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged to intersect each other between layers. In the belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set to, for example, a range of 10° to 40°. Steel cords are preferably used as the reinforcing cords of the belt layers 7. On the outer circumference of the belt layers 7, at least one belt cover layer 8 is arranged, in which the reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction, for the purpose of improving high-speed durability. Organic fiber cords such as nylon or aramid are preferably used as the reinforcing cords of the belt cover layer 8.

[0021] The tire internal structure described above is a typical example for pneumatic tires, but is not limited to this. Furthermore, the tread pattern formed on the tread portion 1 is also not particularly limited.

[0022] In the above-described pneumatic tire, the tread portion 1 has circumferential grooves 11 extending in the tire's circumferential direction, and these circumferential grooves 11 divide the tread into multiple land portions 12. These land portions 12 are further divided into numerous blocks by, for example, transverse grooves (not shown) extending in the tire's width direction. Multiple holes 13 are formed in the land portions 12 of the tread portion 1 into which stud pins 20 are inserted. As shown in Figures 4 to 6, the stud pin 20 consists of a columnar body portion 21, a tip portion 22 disposed on the tip side of the body portion 21, and a flange portion 23 disposed on the base end side of the body portion 21. The tip portion 22 is made of a material with higher hardness than the body portion 21. The flange portion 23 has a larger outer diameter than the body portion 21. The stud pin 20 is arranged in the tread portion 1 such that the body portion 21 and flange portion 23 are inserted into the holes 13, while the tip portion 21 protrudes from the profile line L of the tread portion 1 (see Figure 7). Since the inner diameter of the hole 13 is slightly smaller than the outer diameter of the body portion 21 of the stud pin 20, the stud pin 20 inserted into the hole 13 is firmly held in place by the tread portion 1.

[0023] In a tire having holes 13 into which stud pins 20 are inserted in the tread portion 1, as shown in Figures 2 and 3, there are annular, continuous flat portions 14 around the holes 13 that have a height matching the profile line L of the tread portion 1. The profile line L of the tread portion 1 is the arc that forms the outline of the tread portion 1 in the meridional cross-section of the tire. In Figures 2 and 3, there is a portion around the holes 13 that is slightly shallower than the profile line L for design reasons, but this portion is not necessarily required.

[0024] In Figure 3, a virtual circle C1 is depicted with a distance X1 of 4 mm from the center O of the hole 13, a virtual circle C2 is depicted with a distance X2 of 6 mm from the center O of the hole 13, and a virtual circle C3 is depicted with a distance X3 of 8 mm from the center O of the hole 13. Here, an annular region A is defined around the flat portion 14, with a distance of 4 mm to 8 mm from the center O of the hole 13. The annular region A is the region sandwiched between the virtual circles C1 and C3. The annular region A is composed of an inner annular region Ai, with a distance of 4 mm to 6 mm from the center O of the hole 13, and an outer annular region Ao, with a distance of 6 mm to 8 mm from the center O of the hole 13. At this time, within the annular region A, there are multiple convex portions 15 that rise outward in the tire radial direction from the flat portion 14 and multiple concave portions 16 that are recessed inward in the tire radial direction from the flat portion 14, and these convex portions 15 and concave portions 16 are mixed within the annular region A. In Figure 3 and subsequent drawings, the recess 16 is shaded to facilitate understanding.

[0025] As described above, in a tire equipped with holes 13 in the tread portion 1 into which stud pins 20 are inserted, a flat portion 14 exists around the hole 13 that is connected in an annular shape and coincides with the profile line L of the tread portion 1. Therefore, as shown in Figure 7, the stud pin 20 can be stably held when it is inserted into the hole 13 of the tread portion 1. Moreover, when an annular region A is defined around the flat portion 14 at a distance of 4 mm to 8 mm from the center O of the hole 13, a convex portion 15 that is raised higher than the flat portion 14 and a concave portion 16 that is recessed lower than the flat portion 14 are mixed within this annular region A. Therefore, when the stud pin 20 collapses, the force acting in the direction of collapse is distributed based on the presence of the concave portion 16, preventing the stud pin 20 from falling out. In this case, if the rigidity is drastically reduced due to the presence of the concave portion 16, the stud pin 20 may become more prone to collapse, potentially worsening the pin-loosening resistance. However, the presence of the convex portion 15 along with the concave portion 16 within the annular region A compensates for this lack of rigidity. Therefore, the presence of both the convex portion 15 and the concave portion 16 within the annular region A effectively improves resistance to pin detachment. Furthermore, as described above, the structure that disperses the force when the stud pin 20 falls over weakens the force with which the stud pin 20 attacks the road surface when driving on a dry road surface, thus also improving road surface damage. In this way, resistance to pin detachment can be improved without worsening road surface damage.

[0026] To optimize the cushioning effect of the recess 16, the maximum width of the recess 16 measured radially from the center O of the hole 13 should be 0.5 mm or more and less than 2 mm. Furthermore, to optimize pin pull-out resistance, the area ratio of the recess 16 to the annular region A should be 10% to 50%, the area ratio of the convex portion 15 to the annular region A should be 10% to 90%, and the area ratio of the convex portion 15 and the recess 16 to the annular region A should be less than 90%.

[0027] In the above-described pneumatic tire, as shown in Figure 3, the recesses 16 are arranged on a concentric circle P1 centered on the hole 13, and the recesses 16 have an intermittent shape in a part of the circumferential direction of the concentric circle P1. In Figure 3, multiple protrusions 15 and multiple recesses 16 are arranged alternately at intervals on the concentric circle P1. In addition, multiple protrusions 15 are arranged at intervals on a concentric circle P2 set outside the concentric circle P1 centered on the hole 13. If the recesses 16 are continuous in the circumferential direction of the concentric circle P1 centered on the hole 13, the stud pins 20 will be prone to collapsing due to insufficient rigidity, which is disadvantageous in terms of resistance to pin detachment. However, by having a shape in which the recesses 16 are intermittent in a part of the circumferential direction of the concentric circle P1, rigidity around the stud pins 20 can be ensured, and the stud pins 20 can be prevented from falling out.

[0028] Figures 8(a) to 8(c) show modified examples of the stud pin installation area. In Figure 8(a), the convex portion 15 is arranged on a concentric circle P2 and has a shape that is continuous in the circumferential direction of the concentric circle P2, and the concave portion 16 is arranged on a concentric circle P1 and has a shape that is continuous in the circumferential direction of the concentric circle P1. In Figure 8(b), the convex portion 15 is arranged on a concentric circle P2 and has a shape that is continuous in the circumferential direction of the concentric circle P2, and the concave portion 16 is arranged on a concentric circle P1 and has an intermittent shape in a part of the circumferential direction of the concentric circle P1. In Figure 8(c), the convex portion 15 is arranged on a concentric circle P2 and has a shape that is continuous in the circumferential direction of the concentric circle P2, and the concave portion 16 is arranged on a concentric circle P1 and has a circular shape in plan view. Thus, the shape and arrangement of the convex portion 15 and the concave portion 16 can be changed according to the required performance and design.

[0029] Figures 9(a) to 9(d) show other variations of the stud pin installation portion. In the embodiment of Figure 1 described above, the convex portion 15 and the concave portion 16 are arranged symmetrically on concentric circles P1 and P2. In contrast, in Figures 9(a) to 9(c), the convex portion 15 and the concave portion 16 are arranged asymmetrically on concentric circle P1. Also, in Figure 9(d), a part of the convex portion 15 is straight.

[0030] Figure 10 shows yet another modification of the stud pin installation portion. In Figure 10, the recess 16 is positioned so as not to overlap with the circumferential line Lc that passes through the center O of the hole 13 and is parallel to the tire circumferential direction. In this case, excessive tilting of the stud pin 20 is suppressed during rapid acceleration and deceleration, and the detachment of the stud pin 20 can be effectively prevented.

[0031] Furthermore, in Figure 10, the recess 16 is positioned so as not to overlap with the widthwise line Lw that passes through the center O of the hole 13 and is perpendicular to the tire circumferential direction. In this case, excessive tilting of the stud pin 20 is suppressed during sharp turns, and the detachment of the stud pin 20 can be effectively prevented.

[0032] In Figure 3, an inner annular region Ai is defined within the annular region A, where the distance from the center O of the hole 13 is 4 mm to 6 mm, and an outer annular region Ao is defined where the distance from the center O of the hole 13 is 6 mm to 8 mm. The inner annular region Ai is the region sandwiched between virtual circles C1 and C2, and the outer annular region Ao is the region sandwiched between virtual circles C2 and C3. In this case, it is preferable that the area of ​​the recess 16 included in the inner annular region Ai is set to be larger than the area of ​​the recess 16 included in the outer annular region Ao. By having a relatively large number of recesses 16 in the inner annular region Ai in this way, the force generated when a strong force acts on the stud pin 20 is effectively dispersed, thereby improving the pin pull-out resistance.

[0033] Figures 11(a) to (e) show further variations of the stud pin installation portion. In Figures 11(a) to (e), the recesses 16 are positioned on two of the multiple concentric circles P1 to P3 centered on the hole 13. Specifically, in Figure 11(a), the recesses 16 that are continuous along the concentric circles P1 and P2 are positioned on the concentric circles P1 and P2, and the convex portion 15 that is continuous along the concentric circle P3 is positioned on the concentric circle P3, with the portion between the recesses 16, 16 positioned on the concentric circles P1 and P2 being at the height of the profile line L. In Figure 11(b), the recesses 16 that are continuous along the concentric circles P1 and P3 are positioned on the concentric circles P1 and P3, and the convex portion 15 that is continuous along the concentric circle P2 is positioned on the concentric circle P2. In Figures 11(c) and (d), recesses 16 having an intermittent shape in a part of the circumferential direction of concentric circles P1 and P2 are arranged on concentric circles P1 and P2, and protrusions 15 that are continuous along concentric circle P3 are arranged on concentric circle P3. In Figure 11(e), protrusions 15 and recesses 16 having an intermittent shape in a part of the circumferential direction of concentric circles P1 and P2 are arranged alternately on concentric circles P1 and P2, and protrusions 15 that are continuous along concentric circle P3 are arranged on concentric circle P3. By arranging the recesses 16 on multiple concentric circles P1 to P3 centered on the hole 13 in this way, the force acting in the direction of the stud pin 20 falling over can be effectively distributed, preventing the stud pin 20 from falling out.

[0034] In particular, as shown in Figures 11(a) and (b), when the recesses 16 on multiple concentric circles P1 to P3 are arranged so as to overlap each other in the radial direction of the concentric circles P1 to P3, the force acting on the stud pin 20 when it falls over is effectively distributed, preventing the stud pin 20 from falling out, while also significantly improving road surface damage resistance. Furthermore, as shown in Figures 11(c) to (e), when the recesses 16 on multiple concentric circles P1 to P3 are arranged so as to not overlap each other in the radial direction of the concentric circles P1 to P3, the force acting on the stud pin 20 when it falls over is effectively distributed, and rigidity can be ensured to prevent excessive falling of the stud pin 20, thus significantly improving pin detachment resistance.

[0035] Figure 12 shows yet another modification of the stud pin installation portion. As shown in Figure 5, the body portion 21 of the stud pin 20 has a dimension D1 in a first direction and a dimension D2 in a second direction perpendicular to the first direction in a plan view of the tread portion 1 (i.e., a plan view of the stud pin 20), where dimension D1 is larger than dimension D2, and the first direction is the longitudinal direction T. When the body portion 21 of the stud pin 20 has a longitudinal direction T in a plan view of the tread portion 1 in this way, as shown in Figure 12, when an inner annular region Ai is defined within the annular region A where the distance from the center O of the hole 13 is 4 mm to 6 mm, and an outer annular region Ao is defined where the distance from the center O of the hole 13 is 6 mm to 8 mm, it is preferable that the recess 16 is positioned within the inner annular region Ai so as not to overlap with a virtual line Tx that passes through the center O of the hole 13 and is parallel to the longitudinal direction T of the body portion 21. In other words, if the distance between the body portion 21 of the stud pin 20 and the recess 16 is too close, the pin may not come loose due to insufficient rigidity. However, by positioning the recess 16 within the inner annular region Ai at a location that does not overlap with a virtual line Tx that passes through the center O of the hole 13 and is parallel to the longitudinal direction T of the body portion 21, the pin's resistance to coming loose can be effectively improved.

[0036] In the above-described pneumatic tire, the depth Hy of the recess 16 (see Figure 2) should satisfy the relationship 0.05Hs ≤ Hy ≤ 0.25Hs with respect to the height Hs of the stud pin 20 (see Figure 6), and the height Hx of the protrusion 15 (see Figure 2) should satisfy the relationship 0.10Hy ≤ Hx ≤ 0.80Hy with respect to the depth Hy of the recess 16. This effectively improves the resistance to pin detachment. If the depth Hy of the recess 16 and the height Hx of the protrusion 15 fall outside the above ranges, the improvement in pin detachment resistance decreases. For example, if the height Hs of the stud pin 20 is 9 mm to 10 mm, the depth Hy of the recess 16 can be set to a range of 0.5 mm to 2.0 mm, and the height Hx of the protrusion 15 can be set to a range of 0.2 mm to 1.0 mm. [Examples]

[0037] In a pneumatic tire with a tire size of 205 / 55R16 and a tread portion with holes for inserting stud pins, pneumatic tires were manufactured according to the following specifications: presence or absence of a flat portion formed around the hole, presence or absence of a recess in the annular region, presence or absence of a convex portion in the annular region, presence or absence of intermittent recesses, presence or absence of a recess overlapping with a circumferential line passing through the center of the hole, presence or absence of a recess overlapping with a widthwise line passing through the center of the hole, area of ​​recesses included in the inner annular region, area of ​​recesses included in the outer annular region, area ratio of recesses to the annular region, area ratio of convex portion to the annular region, number of overlapping recesses in the radial direction of concentric circles, and presence or absence of a recess overlapping with an imaginary line passing through the center of the hole in the inner annular region that is parallel to the longitudinal direction of the stud pin body, as shown in Tables 1 and 2. The stud pins are inserted into the holes so that the longitudinal direction of the body is oriented in the tire width direction. In this specification, Example 1 is for reference only.

[0038] These test tires were evaluated for pin detachment resistance and road surface damage resistance using the following test methods, and the results are shown in Tables 1 and 2.

[0039] Pin pull resistance: Each test tire was mounted on a 16x6.5J rim wheel and fitted to a 1.4L front-wheel-drive vehicle. The tire was then inflated to the vehicle's specified air pressure, and after 20,000 km of driving in a designated city driving mode on an outdoor test course consisting of asphalt, the number of pins that came loose was measured. The evaluation results were expressed as an index using the reciprocal of the measured value, with the conventional example set to 100. A higher index value indicates better pin-loosening resistance.

[0040] Road damage: Each test tire was mounted on a 16x6.5J rim wheel and fitted to a 1.4L front-wheel-drive vehicle. The tire pressure was set to 250kPa, and the vehicle was driven 200 times at a speed of 100km / h on a granite plate placed on the road surface. After the test, the amount of road surface wear was measured based on the weight difference of the plate before and after the test. The evaluation results were expressed as an index using the reciprocal of the measured value, with the conventional example set to 100. A higher index value indicates less road surface wear and superior road surface damage resistance.

[0041] [Table 1]

[0042] [Table 2]

[0043] As can be seen from Tables 1 and 2, the tires of Examples 1 to 9 showed improved road surface damage resistance and pin detachment resistance compared to the conventional example. On the other hand, in the tires of Comparative Examples 1 and 2, although there were recesses in the annular region, there were no protrusions in the annular region, resulting in poor pin detachment resistance due to insufficient rigidity. In the tire of Comparative Example 3, although there were protrusions in the annular region, there were no recesses in the annular region, so no improvement in pin detachment resistance was obtained. In the tire of Comparative Example 4, there were no flat areas around the holes, resulting in poor pin detachment resistance.

[0044] This disclosure encompasses the following inventions: Invention [1] A tire having holes in the tread portion into which stud pins are inserted, wherein a flat portion exists around the hole that is connected in an annular shape and coincides with the profile line of the tread portion, and when an annular region is defined around the flat portion at a distance of 4 mm to 8 mm from the center of the hole, the annular region is characterized in that a convex portion that is raised higher than the flat portion and a concave portion that is recessed lower than the flat portion are mixed together. Invention [2] The tire according to Invention [1], characterized in that the recesses are arranged on concentric circles centered on the hole, and the recesses have an intermittent shape in a part of the circumferential direction of the concentric circles. Invention [3] The tire according to Invention [2], characterized in that the recess is positioned so as not to coincide with a circumferential line that passes through the center of the hole and is parallel to the circumferential direction of the tire. Invention [4] The tire according to Invention [2], characterized in that the recess is positioned so as not to overlap with a widthwise line that passes through the center of the hole and is perpendicular to the circumferential direction of the tire. Invention [5] A tire according to any one of Inventions [1] to [4], characterized in that when an inner annular region is defined within the annular region such that the distance from the center of the hole is 4 mm to 6 mm and an outer annular region such that the distance from the center of the hole is 6 mm to 8 mm, the area of ​​the recess included in the inner annular region is larger than the area of ​​the recess included in the outer annular region. Invention [6] A tire according to any one of Inventions [1] to [5], characterized in that the recesses are arranged on a plurality of concentric circles centered on the hole. Invention [7] The tire according to Invention [6], characterized in that the recesses on the plurality of concentric circles are arranged to overlap each other in the radial direction of the concentric circles. Invention [8] The tire according to Invention [6], characterized in that the recesses on the plurality of concentric circles are arranged so as not to overlap each other in the radial direction of the concentric circles. Invention [9] The tire according to any one of Inventions [1] to [8], characterized in that when the body portion of the stud pin inserted into the hole has a longitudinal direction in a plan view of the tread portion, and when an inner annular region is defined within the annular region at a distance of 4 mm to 6 mm from the center of the hole and an outer annular region at a distance of 6 mm to 8 mm from the center of the hole, the recess is positioned within the inner annular region at a location that does not overlap with a virtual line passing through the center of the hole and parallel to the longitudinal direction of the body portion. Invention

[10] A tire according to any one of Inventions [1] to [9], characterized in that the depth Hy of the recess satisfies the relationship 0.05Hs ≤ Hy ≤ 0.25Hs with respect to the height Hs of the stud pin, and the height Hx of the protrusion satisfies the relationship 0.10Hy ≤ Hx ≤ 0.80Hy with respect to the depth Hy of the recess. [Explanation of Symbols]

[0045] 1. Tread section 2 Sidewall section 3. Bead section 4. Carcass layer 5 Bead core 6. Bead Filler 7 Belt layer 8 Belt cover layer 11 Circumferential groove 12 Land 13 holes 14 Flat area 15 Convex part 16 recesses 20 stud pins 21 Body part 22 Chip section 23 Flange section

Claims

1. In a tire having holes in the tread portion into which stud pins are inserted, a flat portion exists around the hole that is connected in an annular shape and coincides with the profile line of the tread portion, and when an annular region is defined around the flat portion at a distance of 4 mm to 8 mm from the center of the hole, a convex portion that is raised higher than the flat portion and a concave portion that is recessed lower than the flat portion are mixed within the annular region. A tire characterized in that the recesses are arranged on concentric circles centered on the hole, and the recesses have an intermittent shape in a part of the circumferential direction of the concentric circles.

2. The tire according to claim 1, characterized in that the recess is positioned so as not to overlap with a circumferential line that passes through the center of the hole and is parallel to the circumferential direction of the tire.

3. The tire according to claim 1, characterized in that the recess is positioned so as not to overlap with a widthwise line that passes through the center of the hole and is perpendicular to the tire circumferential direction.

4. The tire according to any one of claims 1 to 3, characterized in that, when an inner annular region is defined within the annular region such that the distance from the center of the hole is 4 mm to 6 mm, and an outer annular region such that the distance from the center of the hole is 6 mm to 8 mm, the area of ​​the recess included in the inner annular region is larger than the area of ​​the recess included in the outer annular region.

5. The tire according to any one of claims 1 to 3, characterized in that the recesses are arranged on a plurality of concentric circles centered on the hole.

6. The tire according to claim 5, characterized in that the recesses on the plurality of concentric circles are arranged to overlap each other in the radial direction of the concentric circles.

7. The tire according to claim 5, characterized in that the recesses on the plurality of concentric circles are arranged so as not to overlap each other in the radial direction of the concentric circles.

8. The tire according to any one of claims 1 to 3, characterized in that the body portion of the stud pin inserted into the hole has a longitudinal direction in a plan view of the tread portion, and when the annular region is defined as having an inner annular region at a distance of 4 mm to 6 mm from the center of the hole and an outer annular region at a distance of 6 mm to 8 mm from the center of the hole, the recess is positioned within the inner annular region at a location that does not overlap with a virtual line passing through the center of the hole and parallel to the longitudinal direction of the body portion.

9. The tire according to any one of claims 1 to 3, characterized in that the depth Hy of the recess satisfies the relationship 0.05Hs ≤ Hy ≤ 0.25Hs with respect to the height Hs of the stud pin, and the height Hx of the protrusion satisfies the relationship 0.10Hy ≤ Hx ≤ 0.80Hy with respect to the depth Hy of the recess.

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