tire

Abstract

To provide a tire that is configured so that a damage on protrusion on a side wall of a lug groove can be suppressed while appropriately maintaining wet performance and steering stability.SOLUTION: A tire comprises a tread part 1 having an annular shape extending in a tire circumferential direction. The tread part 1 has a plurality of lug grooves 13 extending in a tire width direction, where a protrusion 14 is formed on one side wall of at least one lug groove 13 of the plurality of lug grooves 13. A breaking elongation EB100(%) at 100°C of a rubber composition constituting the tread part 1 and a breaking elongation EBRT(%) at a room temperature RT which is selected from a range of 20°C-30°C of the rubber composition satisfy a relational expression of EBRT>EB100, and a groove width Gw of the lug groove 13 and a height Ph of the protrusion 14 at the time when the tire is unloaded satisfy a relational expression of 1.0×105≤[(EBRT+EB100)×(100-RT)×1 / 2]×Gw / Ph≤3.0×105.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a tire having lug grooves extending in the tire width direction in the tread portion, and more specifically to a tire that can suppress damage to protrusions formed on the sidewalls of the lug grooves while maintaining good wet performance and steering stability. [Background technology]

[0002] In order to ensure wet performance, a tire has a tread portion formed with multiple main grooves extending in the tire circumferential direction and multiple lug grooves extending in the tire width direction. In such a tire, when a tire circumferential force is applied to the tread portion not only during braking or driving but also during normal driving, the sidewalls of the lug grooves extending in the tire width direction are deformed so as to collapse. When the sidewalls of the lug grooves are deformed so as to collapse during driving, not only does steering stability decrease, but wet performance also decreases due to the lug grooves being closed.

[0003] To prevent such inconveniences, it has been proposed to provide protrusions on the side walls of the lug grooves and to use the protrusions to suppress deformation of the side walls of the lug grooves (see, for example, Patent Documents 1 to 3). Optimizing the height of the protrusions formed on the side walls of the lug grooves can improve steering stability while maintaining wet performance. However, if the height of the protrusions is greater than necessary, there is a problem in that the protrusions formed on the side walls of the lug grooves can be damaged when they come into contact with the side walls of the lug grooves during demolding in the tire manufacturing process or during tire running. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-351991 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-88288 [Patent Document 3] Japanese Patent Application Publication No. 2019-108091 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a tire that can suppress damage to protrusions formed on the side walls of lug grooves while maintaining good wet performance and steering stability. [Means for solving the problem]

[0006] In order to achieve the above object, the tire of the present invention has a tread portion extending in the tire circumferential direction to form an annular shape, the tread portion having a plurality of lug grooves extending in the tire width direction, a protrusion formed on one sidewall of at least one of the plurality of lug grooves, and a rubber composition constituting the tread portion having an elongation at break EB at 100°C. 100 (%) and elongation at break at room temperature (RT) selected from the range of 20℃ to 30℃ RT (%) and EB RT >EB 100 and the groove width Gw of the lug groove and the height Ph of the protrusion when the tire is unloaded are 1.0×10 5 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph≦3.0×10 5 The present invention is characterized in that the following relationship is satisfied. [Effects of the Invention]

[0007] As a result of extensive research into the protrusions formed on the side walls of the lug grooves, the inventors discovered that when specifying the height of the protrusions, it is important to take into account the breaking elongation characteristics of the rubber composition that constitutes the tread portion, and this led to the present invention.

[0008] That is, in the present invention, the tread portion has a plurality of lug grooves extending in the tire width direction, and a protrusion is formed on one side wall of at least one of the plurality of lug grooves, and the breaking elongation EB at 100°C of the rubber composition constituting the tread portion is100 (%) and elongation at break at room temperature (RT) selected from the range of 20℃ to 30℃ RT (%) and EB RT >EB 100 The relationship between the lug groove width Gw and the protrusion height Ph when the tire is unloaded is 1.0 x 10 5 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph≦3.0×10 5 By satisfying the relationship, the side walls of the lug grooves (i.e., the side walls of the land portions adjacent to the lug grooves) are appropriately prevented from collapsing and deforming during running, so that wet performance and handling stability can be maintained at a good level. In particular, when setting the protrusion height Ph, it is important to consider the relationship between [(EB RT +EB 100 )×(100-RT)×½], it is possible to suppress the loss of protrusions.

[0009] In the present invention, in the cross section of the lug groove, the angle α (°) formed by the line segment on the groove bottom side of the protrusion with respect to the groove wall imaginary line along the side wall of the lug groove and the angle β (°) formed by the line segment on the ground contact side of the protrusion with respect to the groove wall imaginary line along the side wall of the lug groove are within a range of 2.5 × 10 2 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2] / (α+β)≦4.0×10 3 It is preferable to satisfy the following relationship: This makes it possible to effectively prevent breakage of the protrusions while maintaining good wet performance and handling stability.

[0010] The lug groove depth D and the distance Da from the centroid of the protrusion to the bottom of the lug groove are 0.5 x 10 4 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Da / D≦1.0×10 5 It is preferable to satisfy the following relationship: This makes it possible to effectively prevent breakage of the protrusions while maintaining good wet performance and handling stability.

[0011] It is preferable that the length x of the protrusion in the lug groove extension direction and the length y of the protrusion in the lug groove depth direction satisfy the relationship 0.2≦y / x≦1.0, which makes it possible to effectively prevent breakage of the protrusion while maintaining good wet performance and handling stability.

[0012] It is preferable that the lug groove length L and the total length Lb of all the protrusions included in the lug groove in the lug groove extension direction satisfy the relationship 0.3≦Lb / L≦0.8, which makes it possible to effectively prevent breakage of the protrusions while maintaining good wet performance and handling stability.

[0013] 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, the interior thereof can be filled with air, an inert gas such as nitrogen, or other gases.

[0014] In the present invention, an unloaded tire refers to a state in which the tire is mounted on a standard rim and inflated to the standard internal pressure (in the case of a pneumatic tire). Furthermore, a loaded tire refers to a state in which the tire is mounted on a standard rim, inflated to the standard internal pressure, and placed vertically on a flat surface with a standard load applied. A "standard rim" refers to a rim specified for each tire in a standard system, including the standard on which the tire is based. For example, a standard rim in the case of JATMA, a "Design Rim" in the case of TRA, or a "Measuring Rim" in the case of ETRTO. A "standard internal pressure" refers to the air pressure corresponding to the maximum load capacity specified for each tire in a standard system, including the standard on which the tire is based. A "standard load" refers to a load equivalent to 88% of the maximum load capacity specified for each tire in a standard system, including the standard on which the tire is based. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Figure 2] FIG. 2 is a development view showing the tread pattern of the pneumatic tire of FIG. [Figure 3] 3 is a graph showing the relationship between the elongation at break and the temperature of a rubber composition constituting the tread portion. [Figure 4] FIG. 10 is a cross-sectional view showing a lug groove having a protrusion. [Figure 5] FIG. 10 is a cross-sectional view showing a lug groove having a protrusion. [Figure 6] FIG. 10 is a cross-sectional view showing a lug groove having a protrusion. [Figure 7] FIG. 10 is a cross-sectional view showing a modified example of a lug groove having a protrusion. [Figure 8] FIG. 10 is a cross-sectional view showing another modified example of a lug groove having a protrusion. [Figure 9] FIG. 10 is a longitudinal cross-sectional view showing a lug groove having a protrusion. [Figure 10] FIG. 10 is a longitudinal cross-sectional view showing a modified example of a lug groove having a protrusion. [Figure 11] FIG. 10 is a longitudinal cross-sectional view showing another modified example of a lug groove having a protrusion. [Figure 12] FIG. 10 is a longitudinal cross-sectional view showing a lug groove having a protrusion. [Figure 13] FIG. 10 is a longitudinal cross-sectional view showing a modified example of a lug groove having a protrusion. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: Figures 1 to 13 show a pneumatic tire according to an embodiment of the present invention.

[0017] As shown in FIG. 1, the pneumatic tire of this embodiment includes a tread portion 1 extending circumferentially in a ring 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 the sidewall portions 2.

[0018] A carcass layer 4 is mounted between the pair of bead portions 3, 3. This carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inside to the outside of the tire around a bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition and having a triangular cross section is disposed on the outer periphery of the bead core 5.

[0019] On the other hand, multiple belt layers 7 are embedded on the outer peripheral side 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 are arranged so that the reinforcing cords cross each other between the layers. In the belt layers 7, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is set to a range of 10° to 40°, for example. Steel cords are preferably used as the reinforcing cords of the belt layers 7. At least one belt cover layer 8 is arranged on the outer peripheral side of the belt layer 7, with the aim of improving high-speed durability, and the reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. As the reinforcing cords of the belt cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0020] The tire internal structure described above is a typical example of a pneumatic tire, but is not limited thereto. A tread rubber layer R1 is disposed on the outside of the belt layer 7 and the belt cover layer 8 in the tread portion 1, a side rubber layer R2 is disposed on the outside of the carcass layer 4 in the sidewall portion 2, and a rim cushion rubber layer R3 is disposed on the outside of the carcass layer 4 in the bead portion 3.

[0021] As shown in FIG. 2 , four main grooves 11 extending in the tire circumferential direction are formed in the tread portion 1. These main grooves 11 define five rows of land portions 12 in the tread portion 1. The five rows of land portions 12 include a center land portion 12A located on the tire equator CL, a pair of intermediate land portions 12B, 12B located on both sides of the center land portion 12A, and a pair of shoulder land portions 12C, 12C located on the outermost sides in the tire width direction. Each of the center land portion 12A, the intermediate land portion 12B, and the shoulder land portion 12C has a plurality of lug grooves 13 formed at intervals in the tire circumferential direction and extending in the tire width direction. The lug grooves 13 may divide the center land portion 12A, the intermediate land portion 12B, or the shoulder land portion 12C, or may terminate inside the center land portion 12A, the intermediate land portion 12B, or the shoulder land portion 12C. Furthermore, it is not necessary for the lug grooves 13 to be present in all of the center land portion 12A, the intermediate land portion 12B, and the shoulder land portion 12C. Each lug groove 13 has a pair of side walls 13a, 13b facing each other (see FIG. 4).

[0022] In the shoulder land portion 12C, a protrusion 14 protruding toward the other side wall 13a is formed on one side wall 13b of the lug groove 13. The protrusion 14 may be provided to the lug groove 13 formed in the center land portion 12A or the intermediate land portion 12B.

[0023] In the pneumatic tire, the breaking elongation EB at 100°C of the rubber composition constituting the tread rubber layer R1 of the tread portion 1 100 (%) and elongation at break at room temperature EB RT (%) means EB RT >EB 100 The room temperature RT is the room temperature in an environment where normal driving is assumed, and is selected from the range of 20°C to 30°C, for example, 25°C. As shown in FIG. 3, when the horizontal axis represents temperature (°C) and the vertical axis represents breaking elongation (%), the breaking elongation of the rubber composition constituting the tread portion 1 tends to decrease as the temperature increases. Generally, the breaking elongation EB of the rubber composition constituting the tread portion 1 at 100°C is 100 is in the range of 400% to 700%, and the elongation at break EBRT is in the range of 500% to 800%. Therefore, in FIG. 3, the area of ​​the trapezoid enclosed by the solid line and the dashed line [(EB RT +EB 100 ) × (100-RT) × 1 / 2] is a representative value, for example, 0.8 × 10 5 [(EB RT +EB 100 ) × (100-RT) × 1 / 2], the greater the value of [(1.0 × 10) × (100-RT) × 1 / 2], the greater the breaking elongation in the temperature range from room temperature RT, which is the assumed environment during normal driving, to 100°C, which is the assumed environment during vulcanization. Based on this premise, the groove width Gw of the lug groove 13 and the height Ph of the protrusion 14 when the tire is unloaded are 1.0 × 10 5 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph≦3.0×10 5 For example, if Gw / Ph=2.0, then [(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph=1.6×10 5 This becomes:

[0024] In Figure 4, when a normal line L1 of the tread surface S is drawn from the groove bottom of the lug groove 13 toward the tread surface S, a groove wall imaginary line L2 of the sidewall 13b corresponding to the base end position of the protrusion 14, and a measurement line L3 passing through the centroid X of the protrusion 14 (the centroid of the cross section of the lug groove 13) and perpendicular to the normal line L1 are defined, the groove width Gw of the lug groove 13 is the distance from the groove wall imaginary line L2 measured on the measurement line L3 to the sidewall 13a, and the height Ph of the protrusion 14 is the distance from the groove wall imaginary line L2 measured on the measurement line L3 to the maximum protruding position of the protrusion 14. The groove width Gw of the lug groove 13 is set to 1.6 mm or more, for example, and preferably in the range of 2.0 mm to 4.0 mm. The height Ph of the protrusion 14 is set to, for example, 0.2 mm to 2.0 mm.

[0025] In the above-described pneumatic tire, the tread portion 1 has a plurality of lug grooves 13 extending in the tire width direction, and protrusions 14 are formed on the side walls 13b of these plurality of lug grooves 13. The breaking elongation EB at 100°C of the rubber composition constituting the tread portion 1 is100 (%) and elongation at break at room temperature (RT) selected from the range of 20℃ to 30℃ RT (%) and EB RT >EB 100 and the groove width Gw of the lug groove 13 and the height Ph of the protrusion 14 when the tire is unloaded are 1.0×10 5 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph≦3.0×10 5 By satisfying the relationship, the side walls 13a, 13b of the lug grooves 13 (i.e., the side walls of the land portions adjacent to the lug grooves 13) are appropriately prevented from collapsing and deforming during running, so that wet performance and driving stability can be maintained well. In particular, when setting the height Ph of the protrusions 14, it is important to consider the relationship between [(EB RT +EB 100 )×(100-RT)×½], damage to the protrusions 14 during demolding in the tire manufacturing process and during normal running can be suppressed. RT +EB 100 )×(100−RT)×½] is increased to suppress damage to the protrusions 14.

[0026] where [(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph is 1.0×10 5 If the value is less than 1, the protrusions 14 are likely to be damaged when they come into contact with the side walls of the lug grooves 13 during removal from the mold in the tire manufacturing process or when the tire is running. RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph is 3.0×10 5 If the groove width Gw of the lug groove 14 exceeds this value, the groove width Gw of the lug groove 14 becomes wider than the height Ph of the protrusion 14, thereby reducing the effect of improving steering stability. Alternatively, as the breaking elongation of the rubber composition constituting the tread portion 1 increases, the tan δ at 0°C decreases, resulting in a decrease in wet performance.

[0027] In the above pneumatic tire, as shown in FIG. 5, in the cross section of the lug groove 13, the angle α (°) formed by the line segment on the groove bottom side of the protrusion 14 with respect to the groove wall imaginary line L2 along the side wall 13b of the lug groove 13 and the angle β (°) formed by the line segment on the ground contact side of the protrusion 14 with respect to the groove wall imaginary line L2 along the side wall 13b of the lug groove 13 are 2.5×10 2 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2] / (α+β)≦4.0×10 3 It is desirable to satisfy the relationship below. This makes it possible to effectively prevent damage to the protrusions 14. In other words, the larger the value of α+β, the RT +EB 100 )×(100−RT)×½] is increased to suppress damage to the protrusions 14.

[0028] where [(EB RT +EB 100 If the value of [α+β] / (α+β) is outside the above range, the protrusions 14 are likely to be damaged when they come into contact with the side walls 13a of the lug grooves 13 during demolding in the tire manufacturing process or as the tire runs. In particular, from the viewpoint of preventing damage to the protrusions 14, it is preferable to satisfy the relationship α+β≦180°, and it is even more preferable to satisfy the relationship α+β≦120°.

[0029] The shape of the protrusion 14 may be a square prism, a hemisphere (Fig. 6), a triangular pyramid (Fig. 7), etc. As shown in Fig. 6, when the line segment on the groove bottom side of the protrusion 14 and the line segment on the ground side are curved, the angles α and β are measured at the intersection of the protrusion 14 and an imaginary line L2' that passes through the centroid X and is parallel to the groove wall imaginary line L2.

[0030] In the above pneumatic tire, as shown in FIG. 8, the depth D of the lug groove 13 and the distance Da from the position of the centroid X of the protrusion 14 to the groove bottom of the lug groove 13 are 0.5×10 4 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Da / D≦1.0×10 5It is desirable to satisfy the relationship of [(EB RT +EB 100 )×(100−RT)×½] is increased to suppress damage to the protrusions 14.

[0031] where [(EB RT +EB 100 )×(100-RT)×1 / 2]×Da / D is 0.5×10 4 If the EB is less than 1 / 2, the protrusions 14 are difficult to remove from the mold during the tire manufacturing process, and are prone to breakage. RT +EB 100 )×(100-RT)×1 / 2]×Da / D is 1.0×10 5 If Da / D is greater than this, the protrusions 14 will approach the ground contact side, which may impair wet performance. It is preferable that the depth D of the lug grooves 13 and the distance Da from the position of the centroid X of the protrusions 14 to the groove bottom of the lug grooves 13 satisfy the relationship 0.1≦Da / D≦0.7. If Da / D<0.1, the collapse of the side walls 13a, 13b of the lug grooves 13 near the tread surface S is not sufficiently suppressed, which reduces the effect of improving steering stability and wet performance. Conversely, if Da / D>0.7, the protrusions 14 will approach the ground contact side, which may impair wet performance.

[0032] In the above-described pneumatic tire, as shown in Figures 9 to 11, it is preferable that the length x of the protrusion 14 in the lug groove extension direction and the length y of the protrusion 14 in the lug groove depth direction satisfy the relationship 0.2≦y / x≦1.0. This effectively prevents damage to the protrusion 14 while maintaining good wet performance and handling stability. Figure 9 shows a case where the cross-sectional shape of the protrusion 14 is rectangular, Figure 10 shows a case where the cross-sectional shape of the protrusion 14 is elliptical, and Figure 11 shows a case where the cross-sectional shape of the protrusion 14 is a parallelogram. The lengths x and y of the protrusion 14 are dimensions in a cross section that passes through the position of the centroid X of the protrusion 14 and is parallel to the depth direction of the lug groove 13. These lengths x and y of the protrusion 14 are measured at the position of the centroid X. If y / x<0.2, the protrusions 14 become thin, which makes them more susceptible to damage when they come into contact with the side walls 13a of the lug grooves 13 during demolding in the tire manufacturing process or while the tire is running, and also reduces the effect of improving steering stability. Conversely, if y / x>1.0, there is a risk that water flow may be obstructed when running on wet roads.

[0033] In the above-described pneumatic tire, as shown in FIGS. 12 and 13, the length L of the lug groove 13 and the total length Lb of all the protrusions 14 included in the lug groove 13 in the lug groove extension direction preferably satisfy the relationship 0.3≦Lb / L≦0.8. This effectively prevents damage to the protrusions 14 while maintaining good wet performance and handling stability. FIG. 12 shows a case where the longitudinal direction of the protrusions 14 coincides with the lug groove extension direction, while FIG. 13 shows a case where the longitudinal direction of the protrusions 14 is inclined with respect to the lug groove extension direction. The length L of the lug groove 13 is the dimension within the contact area bounded by the contact edge E of the tire under load. The total length Lb of all the protrusions 14 in the lug groove extension direction is, for example, the sum of the lengths Lb1, Lb2,...Lbn of each protrusion 14 in the lug groove extension direction. The lengths Lb1, Lb2,...Lbn of each protrusion 14 are the dimensions of a cross section passing through the position of the centroid X of the protrusion 14 and parallel to the depth direction of the lug groove 13. The lengths Lb1, Lb2, Lbn of these protrusions 14 are measured at the position of the centroid X. If Lb / L<0.3, the collapse of the side walls 13a, 13b of the lug groove 13 is not sufficiently suppressed, resulting in a decrease in the effect of improving steering stability and wet performance. Conversely, if La / L>0.8, more protrusions 14 than necessary are present, which makes it difficult to release from the mold and makes the protrusions 14 more likely to break off.

[0034] In the above pneumatic tire, it is preferable that the protrusions 14 are provided at least in the lug grooves 13 formed in the shoulder land portions 12C. By providing the protrusions 14 at least in the lug grooves 13 formed in the shoulder land portions 12C in this way, it is possible to maximize the effects of improving steering stability and wet performance. Of course, it is also possible to provide the protrusions 14 not only in the shoulder land portions 12C but also in the lug grooves 13 formed in the intermediate land portions 12B and the center land portion 12A.

[0035] In the above pneumatic tire, the protrusions 14 are preferably formed in 50% or more, preferably 80% or more, and more preferably 95% or more of all the lug grooves 13 formed in the tread portion 1. This allows for sufficient improvements in steering stability and wet performance. The above specification refers to the installation ratio of the protrusions 14 to the lug grooves 13 arranged throughout the tread portion 1, including the center land portion 12A, the intermediate land portion 12B, and the shoulder land portion 12C. The desired effect can be achieved even if the protrusions 14 are arranged only in the center land portion 12A, only in the intermediate land portion 12B, or only in the shoulder land portion 12C. [Example]

[0036] The tire size was 205 / 55R16, and the pneumatic tires had a tread portion, a pair of sidewall portions, and a pair of bead portions. The tires of the conventional example, comparative examples 1 and 2, and examples 1 to 8 were manufactured in which protrusions were provided on one side wall of the lug grooves formed in the tread portion. The rubber composition constituting the tread portion was selected from the group consisting of a rubber composition having a breaking elongation at 100°C, EB 100 (%) and elongation at break EB at room temperature (25°C) RT (%) and EB RT >EB 100 A rubber composition satisfying the relationship was used.

[0037] In the conventional example, comparative examples 1 to 2, and examples 1 to 8, the groove width Gw of the lug groove, the height Ph of the protrusion, [(EB RT +EB 100 ) × (100-RT) × 1 / 2] × Gw / Ph, [(EB RT +EB 100 )×(100-RT)×1 / 2] / (α+β), [(EB RT +EB 100 )×(100−RT)×1 / 2×Da / D, y / x, and Lb / L were set as shown in Table 1.

[0038] These test tires were evaluated for the number of remaining projections after vulcanization, the number of remaining projections after running, wet performance, and steering stability using the following test methods. The results are also shown in Table 1.

[0039] Number of remaining protrusions after vulcanization: Immediately after vulcanization of each test tire, the number of protrusions that were not cracked or chipped was counted. The evaluation results were expressed as an index, with the number of designed protrusions set at 100. The higher the index value, the greater the number of remaining protrusions that were not damaged.

[0040] Number of remaining protrusions after vulcanization: Each test tire was mounted on a 16x6.5J rim wheel and fitted to a 1500cc test vehicle, the air pressure was set to 220kPa, and the vehicle was driven 8000km on a test course consisting of a dry asphalt surface, after which the number of protrusions that were not cracked or chipped was counted. The evaluation results were expressed as an index, with the number of designed protrusions set to 100. The higher the index value, the greater the number of remaining protrusions that were not damaged.

[0041] Wet Performance: Each test tire was mounted on a 16x6.5J rim wheel and mounted on a 1500cc test vehicle, the tire pressure was set to 220kPa, and the vehicle was braked from a speed of 100km / h on a test course consisting of a wet road surface with 1mm of water, and the braking distance was measured. The evaluation results were expressed as an index using the reciprocal of the measured value, with the conventional example being set at 100. The higher the index value, the better the wet performance.

[0042] Handling stability: Each test tire was mounted on a 16x6.5J rim wheel and mounted on a 1500cc test vehicle, the air pressure was set to 220kPa, and a sensory evaluation was carried out by a test driver on a test course consisting of a dry asphalt road surface. The evaluation results were expressed as an index, with the conventional example being set at 100. The higher the index value, the better the handling stability.

[0043] [Table 1]

[0044] As can be seen from Table 1, the tires of Examples 1 to 8 were able to suppress damage to the protrusions formed on the sidewalls of the lug grooves while maintaining good wet performance and steering stability in comparison with the conventional tire. On the other hand, the tire of Comparative Example 1 had a [(EB RT +EB 100 )×(100-RT)×½]×Gw / Ph was too small, and therefore, the protrusions formed on the side walls of the lug grooves were frequently damaged. RT +EB 100 ) × (100 - RT) × 1 / 2 × Gw / Ph was too large, resulting in poor wet performance.

[0045] The present disclosure includes the following inventions [1] to [5]. Invention [1] is a tire having a tread portion extending in the tire circumferential direction to form an annular shape, wherein the tread portion has a plurality of lug grooves extending in the tire width direction, and a protrusion is formed on one side wall of at least one of the plurality of lug grooves, and the breaking elongation EB at 100°C of the rubber composition constituting the tread portion is 100 (%) and elongation at break at room temperature (RT) selected from the range of 20℃ to 30℃ RT (%) and EB RT >EB 100 and the groove width Gw of the lug groove and the height Ph of the protrusion when the tire is unloaded are 1.0×10 5 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph≦3.0×10 5 The tire is characterized by satisfying the relationship: Invention [2] is a technology in which, in a cross section of the lug groove, the angle α (°) formed by a line segment on the groove bottom side of the protrusion with respect to a groove wall imaginary line along the side wall of the lug groove and the angle β (°) formed by a line segment on the ground contact side of the protrusion with respect to the groove wall imaginary line along the side wall of the lug groove are 2.5 × 10 2 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2] / (α+β)≦4.0×10 3 The tire according to the invention [1] is characterized in that it satisfies the relationship: The invention [3] is characterized in that the depth D of the lug groove and the distance Da from the centroid position of the protrusion to the groove bottom of the lug groove are 0.5 × 10 4 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Da / D≦1.0×10 5 The tire according to the invention [1] or [2] is characterized in that the following relationship is satisfied. Invention [4] is a tire according to any one of inventions [1] to [3], characterized in that the length x of the protrusion in the lug groove extension direction and the length y of the protrusion in the lug groove depth direction satisfy the relationship 0.2≦y / x≦1.0. Invention [5] is a tire according to any one of inventions [1] to [4], characterized in that the length L of the lug groove and the total length Lb of all protrusions included in the lug groove in the lug groove extension direction satisfy the relationship 0.3≦Lb / L≦0.8. [Explanation of symbols]

[0046] 1 Tread section 2 Sidewall 3 Bead section 11 Main groove 12,12A,12B,12C Land part 13 Lug groove 14 protrusions

Claims

1. A tire having a tread portion extending in a tire circumferential direction to form an annular shape, the tread portion having a plurality of lug grooves extending in a tire width direction, a protrusion formed on one side wall of at least one of the plurality of lug grooves, and a rubber composition constituting the tread portion having a breaking elongation at 100°C (EB 100 (%) and elongation at break EB at room temperature RT selected from the range of 20°C to 30°C RT (%) and EB RT >EB 100 and the groove width Gw of the lug groove and the height Ph of the protrusion when the tire is unloaded are 1.0×10 5 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Gw / Ph≦3.0×10 5 A tire characterized by satisfying the relationship:

2. In a cross section of the lug groove, the angle α (°) formed by a line segment on the groove bottom side of the protrusion with respect to a groove wall imaginary line along the side wall of the lug groove and the angle β (°) formed by a line segment on the ground contact side of the protrusion with respect to the groove wall imaginary line along the side wall of the lug groove are 2.5 × 10 2 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2] / (α+β)≦4.0×10 3 2. The tire according to claim 1, wherein the following relationship is satisfied:

3. The depth D of the lug groove and the distance Da from the centroid position of the protrusion to the groove bottom of the lug groove are 0.5×10 4 ≦[(EB RT +EB 100 )×(100-RT)×1 / 2]×Da / D≦1.0×10 5 3. The tire according to claim 1, wherein the following relationship is satisfied:

4. 3. The tire according to claim 1, wherein a length x of the projection in the lug groove extension direction and a length y of the projection in the lug groove depth direction satisfy the relationship 0.2≦y / x≦1.

0.

5. 3. The tire according to claim 1, wherein the length L of the lug groove and the total length Lb of all the protrusions included in the lug groove in the lug groove extension direction satisfy the relationship 0.3≦Lb / L≦0.8.

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