tire

Abstract

To provide a tire capable of improving on-snow performance, and steering stability on dry road surfaces.SOLUTION: A tire 1 comprises a buttress surface 13 extending from a tread ground-contact end Te to the inside in a tire radial direction. The tire 1 has a plurality of strip grooves 15 that are recessed inward from the buttress surface 13, and that extend across the buttress surface 13; and a plurality of protrusion strips 16 that protrude outward from the buttress surface 13, and that extend across the buttress surface 13. The strip grooves 15 and the protrusion strips 16 are alternately arranged.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a tire.

Background Art

[0002] The following Patent Document 1 describes a pneumatic tire (hereinafter sometimes simply referred to as "tire"). From the viewpoint of improving snow performance, a plurality of protrusions arranged along the tire circumferential direction are provided in a buttress portion between a tread portion and a sidewall portion.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above buttress portion, the rubber volume increases due to the plurality of protrusions, and the rigidity increases. Therefore, the rigidity difference between the buttress portion and the sidewall portion increases. Such a rigidity difference generates local strain and causes a decrease in handling stability on a dry road surface, so there is room for further improvement in terms of improving handling stability performance.

[0005] The present disclosure has been devised in view of the above actual situation, and the main object is to provide a tire capable of improving snow performance and handling stability on a dry road surface.

Means for Solving the Problems

[0006] The present disclosure relates to a tire having a buttress surface extending radially inward from the tread contact edge, wherein the tire has a plurality of grooves that are recessed inward from the buttress surface and extend along the buttress surface, and a plurality of protrusions that project outward from the buttress surface and extend along the buttress surface, and the grooves and protrusions are arranged alternately. [Effects of the Invention]

[0007] By adopting the above configuration, the tires disclosed herein can improve both snow performance and handling stability on dry surfaces. [Brief explanation of the drawing]

[0008] [Figure 1] This is a meridian cross-section of the tire, including the tire's axis of rotation in its normal state. [Figure 2] Figure 1 is a perspective view of the shoulder area. [Figure 3] This is a front view of the buttress surface, including grooves and protrusions. [Figure 4] This is a cross-sectional view AA in Figure 3. [Figure 5] This is a partial cross-sectional view showing grooves and protrusions of other embodiments of the present disclosure. [Figure 6] This is a front view of the buttress surface including grooves and protrusions of the embodiment of the disclosure. [Figure 7] This is a front view of the buttress surface including grooves and protrusions of the embodiment of the disclosure. [Figure 8] This is a front view of the buttress surface of Comparative Example 1. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described below with reference to the drawings. It should be understood that the drawings contain exaggerations and representations that differ from the actual structural proportions in order to aid in understanding the content of the disclosure. Furthermore, the same or common elements are denoted by the same reference numerals throughout each embodiment, and redundant explanations are omitted. Moreover, the specific configurations shown in the embodiments and drawings are for the purpose of understanding the content of this disclosure, and this disclosure is not limited to the specific configurations shown.

[0010] [Tire (First Embodiment)] Figure 1 shows an example of a tire meridian cross-section including the tire rotation axis in the normal state of the tire of this embodiment. In Figure 1, the dashed line represents the tire equator (equatorial plane) C.

[0011] The tire 1 of this embodiment is suitably used, for example, as a pneumatic tire for passenger cars. However, this disclosure is not limited to this embodiment, and may also be used, for example, as a pneumatic tire for heavy loads or as a non-pneumatic tire (airless tire) in which pressurized air is not filled inside the tire. Furthermore, the tire 1 of this embodiment is suitably used as a winter tire. Note that winter tires refer to tires 1 suitable for driving on snow, including studless tires, snow tires, all-season tires, etc.

[0012] "Normal condition" refers to the unloaded state in which tire 1 is mounted on a normal rim (hereinafter sometimes simply referred to as "rim") and adjusted to the normal internal pressure. Unless otherwise specified in this specification, the dimensions of each part of tire 1 are values ​​measured in this normal condition.

[0013] A "regular rim" is the rim specified for each tire in the standard system that includes the standard on which the tire is based. Therefore, a regular rim is, for example, a "standard rim" for JATMA, a "design rim" for TRA, or a "measuring rim" for ETRTO.

[0014] The "normal internal pressure" is the air pressure defined for each tire in a standard system including the standards on which the tire 1 is based. Therefore, the normal internal pressure is the "maximum air pressure" in the case of JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and "INFLATION PRESSURE" in the case of ETRTO.

[0015] The tire 1 of the present embodiment has a tread portion 2, a pair of sidewall portions 3 extending radially inward in the tire radius direction from both end portions of the tread portion 2, and bead portions 4 formed radially inward in the tire radius direction of the respective sidewall portions 3. Inside the tire 1 of the present embodiment, for example, a carcass 6 and a belt layer 7 are arranged. Known configurations can be applied to these.

[0016] [Tread portion] The tread portion 2 of the present embodiment includes a plurality of circumferential grooves 8 continuously extending in the tire circumferential direction and land portions 9 partitioned by the circumferential grooves 8. The land portions 9 may be partitioned into a plurality of blocks, for example, by transverse grooves (not shown) extending in a direction intersecting the circumferential grooves 8.

[0017] In the land portion 9 of the present embodiment, a shoulder land portion 10 including a tread grounding end Te is provided. The tread grounding end Te is specified as the outermost grounding position (excluding the protruding portion 12 described later) in the tire axial direction when a normal load is applied to the tire 1 in the above-described normal state and the tire is grounded on a plane at a camber angle of 0°.

[0018] The "normal load" is the load defined for each tire in a standard system including the standards on which the tire is based. Therefore, the normal load is the "maximum load capacity" in the case of JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and "LOAD CAPACITY" in the case of ETRTO.

[0019] Figure 2 is a perspective view of the shoulder land portion 10 of FIG. 1. In the shoulder land portion 10 of the present embodiment, a sipe 11 and a protrusion 12 are provided. The sipe 11 and the protrusion 12 of the present embodiment are provided at intervals in the tire circumferential direction. A "sipe" is one having a width of less than 1.5 mm and is distinguished from the circumferential groove 8 and the transverse groove (not shown) having a groove width of 1.5 mm or more.

[0020] [Sipe] The sipe 11 of the present embodiment extends in the tire axial direction. Note that the sipe 11 is not limited to such a mode. The sipe 11 may extend in the tire circumferential direction, for example. Further, the sipe 11 of the present embodiment extends in a zigzag shape in the longitudinal direction, but is not particularly limited. The sipe 11 may extend linearly, for example. These sipes 11 enhance the edge component in the shoulder land portion 10 and improve the ice performance.

[0021] [Protrusion] As shown in FIGS. 1 and 2, the protrusion 12 of the present embodiment protrudes from the tire outer surface 1s (the buttress surface 13). As shown in FIG. 2, the protrusion 12 of the present embodiment is disposed on the outer side in the tire axial direction with respect to the outer end 11o in the tire axial direction of the sipe 11 and the tread ground contact end Te. Further, the inner end 12i in the tire radial direction of the protrusion 12 terminates without reaching the later-described groove 15 and rib 16. Such a protrusion 12 can increase the ground contact area during turning and improve the turning performance on ice and snow roads. The width W1 of the protrusion 12 is set to about 0.5 to 7.0 mm, for example. The maximum height H1 of the protrusion 12 is set to about 2.0 to 5.0 mm, for example.

[0022] [Buttress surface] As shown in FIG. 1, the tire 1 of the present embodiment includes a buttress surface 13 that extends radially inward from the tread ground contact end Te. The buttress surfaces 13 are provided in the buttress portions 5 between the tread portion 2 and the sidewall portion 3, respectively.

[0023] As shown in Figure 2, the buttress surface 13 of this embodiment is provided with a plurality of grooves 15 and a plurality of protrusions 16. These grooves 15 and protrusions 16 are arranged alternately. In this embodiment, the grooves 15 and protrusions 16 are provided on both sides of the buttress surface 13 in the tire axial direction, but they may also be provided on only one side of the buttress surface 13.

[0024] [Groove] In this embodiment, the multiple grooves 15 are recessed inward from the buttress surface 13 and extend from the buttress surface 13. In this embodiment, when the protruding portion 12, grooves 15, and raised ridges 16 are provided, the outer surface of the tire other than the protruding portion 12, grooves 15, and raised ridges 16 (a virtual surface formed by smoothly connecting the outer surface 1s of the tire (shown in Figure 1)) is identified as the buttress surface 13.

[0025] Figure 3 is a front view of the buttress surface 13 including grooves 15 and protrusions 16. In Figure 3, each groove 15 is color-coded for easy distinction from each protrusion 16. In this embodiment, each groove 15 extends linearly between its outer end 15o and inner end 15i in the tire radial direction when viewed from the front of the buttress surface 13. Each groove 15 may be curved in part between its outer end 15o and inner end 15i. As shown in Figure 2, the outer end 15o of each groove 15 in this embodiment is located further inward in the tire radial direction than the tread contact edge Te and the inner end 12i of the protrusion 12.

[0026] Figure 4 is a cross-sectional view of AA in Figure 3. Each groove 15 in this embodiment is composed of a pair of groove walls 15w, 15w and a groove bottom 15b connected to the groove walls 15w, 15w in a cross-section perpendicular to the longitudinal direction of each groove 15. In this embodiment, the groove width W3 of each groove 15 gradually decreases from the buttress surface 13 toward the inside (groove bottom 15b side) and is formed in a triangular cross-section.

[0027] [Convex] As shown in Figure 2, the multiple protrusions 16 of this embodiment protrude outward from the buttress surface 13 and extend along the buttress surface 13. As shown in Figure 3, in a front view of the buttress surface 13, each protrusion 16 of this embodiment extends linearly between its outer end 16o and inner end 16i in the tire radial direction, similar to each groove 15. Each protrusion 16 may be curved at least partially between its outer end 16o and inner end 16i. As shown in Figure 2, the outer end 16o of the protrusion 16 of this embodiment is located further inward in the tire radial direction than the tread contact edge Te and the inner end 12i of the protruding portion 12.

[0028] As shown in Figure 4, each ridge 16 in this embodiment is composed of a pair of side walls 16w, 16w and a tip portion 16t connected to the side walls 16w, 16w in a cross section perpendicular to the longitudinal direction of each ridge 16. Each groove 15 in this embodiment has a width W4 that gradually decreases outward from the buttress surface 13 (towards the tip portion 16t), and is formed in a triangular cross-section.

[0029] [The function of tires] As shown in Figures 2 to 4, the tire 1 of this embodiment has alternating grooves 15 and protrusions 16 on the buttress surface 13, which allows large snow columns to form in the grooves 15 sandwiched between pairs of protrusions 16, 16 when driving on a deep snow surface. As a result, the tire 1 can obtain great traction by shearing these large snow columns. Therefore, snow performance (traction performance) is improved.

[0030] Furthermore, in this embodiment, the tire 1 has multiple protrusions 16 that project outward from the buttress surface 13, which compensate for the reduction in rubber volume caused by multiple grooves 15 that recess inward from the buttress surface 13. As a result, in this embodiment, the difference in rigidity between the buttress portion 5, where the grooves 15 and protrusions 16 are provided, and the sidewall portion 3 (shown in Figure 1), which is located radially inward of the buttress portion 5, is suppressed, and the occurrence of localized distortion between them is prevented. Therefore, the tire 1 of this embodiment has improved handling stability on dry road surfaces.

[0031] As shown in Figure 2, the outer end 15o of each groove 15 in this embodiment is located radially inward of the inner end 12i of the protruding portion 12. As a result, the rubber volume reduced by the multiple grooves 15 is also compensated for by the protruding portion 12, thereby improving handling stability on dry road surfaces.

[0032] As shown in Figures 2 and 3, the longitudinal direction of each groove 15 and each protrusion 16 in this embodiment is inclined with respect to the tire circumferential direction. As a result, the snow columns formed in the groove 15 sandwiched between the pair of protrusions 16, 16 are efficiently sheared as the tire 1 rotates, thereby improving snow performance.

[0033] As shown in Figure 3, the angle θ1 of each groove 15 and each protrusion 16 in the longitudinal direction with respect to the tire circumferential direction is preferably set to 20 to 70 degrees. Setting the angle θ1 to 20 degrees or more allows snow columns formed in the groove 15 sandwiched between the pair of protrusions 16, 16 to be efficiently sheared, improving grip when turning on deep snow surfaces and improving snow performance. On the other hand, setting the angle θ1 to 70 degrees or less suppresses the longitudinal direction of each groove 15 and each protrusion 16 from intersecting the tire circumferential direction (direction of tire rotation) at a large angle. This suppresses the distortion of the buttress portion 5 that occurs during tire rotation from becoming large in the groove 15 sandwiched between the pair of protrusions 16, 16, and maintains handling stability on dry surfaces. In order to effectively exert these effects, the angle θ1 is preferably 30 degrees or more, and preferably 60 degrees or less.

[0034] As shown in Figure 4, the maximum depth H3 of each groove 15 and the maximum height H4 of each protrusion 16 are preferably set to 0.5 to 4.0 mm. Setting the maximum depth H3 and maximum height H4 to 0.5 mm or more creates large snow columns in the groove 15 sandwiched between the pair of protrusions 16, 16, improving snow performance. On the other hand, setting the maximum depth H3 and maximum height H4 to 4.0 mm or less suppresses a large difference in rigidity between the part of the buttress 5 where the groove 15 is provided and the part where the protrusion 16 is provided, thus maintaining handling stability on dry surfaces. From this viewpoint, the maximum depth H3 and maximum height H4 are preferably 5.0 mm or more, and preferably 3.5 mm or less.

[0035] The maximum groove width W3m of each groove 15 and the maximum width W4m of each protrusion 16 are preferably 0.5mm or more, more preferably 5.0mm or more, and also preferably 20.0mm or less, and even more preferably 15.0mm or less, from the same viewpoint as the maximum depth H3 of each groove 15 and the maximum height H4 of each protrusion 16.

[0036] As shown in Figure 3, the arrangement pitch P1 of the multiple grooves 15 in the tire circumferential direction, and the arrangement pitch P2 of the multiple protrusions 16 in the tire circumferential direction are preferably set to 2.0 to 10.0 mm. Setting the arrangement pitches P1 and P2 to 10.0 mm or less allows many snow columns to form in the grooves 15 sandwiched between the pairs of protrusions 16, 16, improving snow performance. On the other hand, setting the arrangement pitches P1 and P2 to 2.0 mm or more suppresses the reduction of the maximum groove width W3m of each groove 15 and the maximum width W4m of the protrusions 16, allowing for the formation of large snow columns. From this viewpoint, the arrangement pitches P1 and P2 are preferably 4.0 mm or more, and also preferably 8.0 mm or less.

[0037] The length L1 of each groove 15 and each protrusion 16 in the tire radial direction is preferably set to 10.0 to 30.0 mm. Setting the length L1 to 10.0 mm or more ensures that snow columns are reliably formed in the groove 15 sandwiched between the pair of protrusions 16, 16, improving snow performance. On the other hand, setting the length L1 to 30.0 mm or less suppresses the formation of each groove 15 and each protrusion 16 over a wide area in the tire radial direction, improving handling stability on dry surfaces.

[0038] The ratio V1 / V2 of the total volume V1 of multiple grooves 15 to the total volume V2 of multiple protrusions is preferably set to 0.7 to 1.3. The total volume V1 is the sum of the volumes of all grooves 15, calculated individually for each groove 15 (the volume of the space enclosed by the buttress surface 13 shown in Figure 4, the groove walls 15w, 15w of each groove 15, and the groove bottom 15b of each groove 15). On the other hand, the total volume V2 is the sum of the volumes of all protrusions 16, calculated individually for each protrusion 16 (the volume of the space enclosed by the buttress surface 13 shown in Figure 4, the side walls 16w, 16w of each protrusion 16, and the tip portion 16t of each protrusion 16).

[0039] By setting the ratio V1 / V2 to 0.7 or higher, the rubber volume reduced by the multiple grooves 15 is compensated for, while preventing the ratio of the raised grooves 16 to the grooves 15 from becoming excessively large. This improves handling stability on dry surfaces while maintaining snow performance. On the other hand, by setting the ratio V1 / V2 to 1.3 or lower, the rubber volume reduced by the multiple grooves 15 is compensated for, while preventing the ratio of the grooves 15 to the raised grooves 16 from becoming excessively large. Therefore, this improves snow performance while maintaining handling stability on dry surfaces. From this viewpoint, the ratio V1 / V2 is preferably 0.8 or higher, and also preferably 1.2 or lower.

[0040] The total volume V1 of the multiple grooves 15 may be set to be smaller than the total volume V2 of the multiple protrusions 16. This reliably suppresses the reduction in rigidity of the buttress section 5 due to the grooves 15, improving handling stability on dry surfaces. In this case, the ratio V1 / V2 is preferably 0.9 or less, and also preferably 0.7 or more.

[0041] [Tire (Second Embodiment)] As shown in Figure 4, the cross-sectional shape of each groove 15 and each ridge 16 in previous embodiments has been exemplified as triangular, but the invention is not limited to this configuration. Figure 5 is a partial cross-sectional view showing the groove 15 and ridge 16 of an embodiment of the present disclosure.

[0042] In this embodiment, the tire 1 has rectangular cross-sectional shapes for each groove 15 and each protrusion 16. Such a tire 1 can form strong rectangular snow columns in the groove 15 sandwiched between the pair of protrusions 16, 16, and by shearing these columns, great traction can be obtained. Therefore, the tire 1 in this embodiment can improve snow performance.

[0043] The cross-sectional shape of each groove 15 and each protrusion 16 may be, for example, a trapezoidal shape (not shown). In this case, the groove width W3 of each groove 15 may gradually decrease or gradually increase from the buttress surface 13 toward the inside (groove bottom 15b side). Such a tire 1 can compact snow columns toward the groove bottom 15b of the groove 15, thereby improving snow performance.

[0044] [Tire (Third Embodiment)] In previous embodiments, as shown in Figure 3, an example has been given in which each groove 15 and each ridge 16 extends linearly (linearly between the outer end 15o and the inner end 15i) in a front view of the buttress surface 13, but the invention is not limited to this embodiment. Each groove 15 and each ridge 16 may be bent with respect to the tire radial direction in a front view of the buttress surface 13, for example. Figure 6 is a front view of a buttress surface 13 including grooves 15 and ridges 16 according to an embodiment of the present disclosure.

[0045] Each groove 15 in this embodiment is composed of a first inclined groove 15A and a second inclined groove 15B. The first inclined groove 15A extends inclined toward one side in the tire circumferential direction from the outer end 15o of the groove 15 toward the radially inward direction of the tire. On the other hand, the second inclined groove 15B extends inclined toward the other side in the tire circumferential direction from the inner end (bent portion 15C) of the first inclined groove 15A toward the inner end 15i of the groove 15. The first inclined groove 15A and the second inclined groove 15B each extend in a straight line. As a result, each groove 15 is provided with a bent portion 15C that protrudes toward one side in the tire circumferential direction between the first inclined groove 15A and the second inclined groove 15B, forming a V-shape in a front view of the buttress surface 13.

[0046] Each ridge 16 in this embodiment is composed of a first inclined ridge 16A and a second inclined ridge 16B. The first inclined ridge 16A extends inclined toward one side in the tire circumferential direction from the outer end 16o of the ridge 16 toward the radially inward direction of the tire. On the other hand, the second inclined ridge 16B extends inclined toward the other side in the tire circumferential direction from the inner end (bent portion 16C) of the first inclined ridge 16A toward the inner end 16i of the ridge 16. The first inclined ridge 16A and the second inclined ridge 16B each extend in a straight line. As a result, each ridge 16 is provided with a bent portion 16C that protrudes toward one side in the tire circumferential direction between the first inclined ridge 16A and the second inclined ridge 16B, forming a V-shape in a front view of the buttress surface 13.

[0047] In this embodiment, the tire 1, with its grooves 15 and protrusions 16 that are bent in the radial direction of the tire, can form a strong, bent (V-shaped in this example) snow column in the groove 15 sandwiched between the pair of protrusions 16, 16. Since such a snow column is strongly compressed toward the bent portion 15C, a large snow column shear force is exerted, improving snow performance.

[0048] In this embodiment, one bent portion 15C and one bent portion 16C are provided in the groove 15 and the protrusion 16, but this is not particularly limited, and multiple bent portions 15C and 16C may be provided in each. As a result, the groove 15 and the protrusion 16 are formed in a zigzag shape, which allows for the formation of stronger snow columns and improves snow performance.

[0049] In this embodiment, when each groove 15 and each protrusion 16 is bent with respect to the tire radial direction, the tire rotation direction R may be specified. The rotation direction R is indicated, for example, by letters or symbols on the sidewall portion 3 (shown in Figure 1).

[0050] In this embodiment, the rotation direction R is specified such that the bent portions 15C and 16C of the grooves 15 and protrusions 16 make contact first. As a result, the tire 1 of this embodiment can collect snow without letting it escape both inside and outside the tire radial direction of each groove 15 and each protrusion 16 during braking while driving straight and turning, forming a solid snow column. This improves the braking performance of the tire 1 on snowy road surfaces.

[0051] The rotation direction R may be specified such that the bent portions 15C and 16C are located later in the grooves 15 and protrusions 16. As a result, the tire 1 of this embodiment can form strong snow columns when driving straight and when turning. This improves the driving performance of the tire 1 on snowy road surfaces.

[0052] [Tire (Fourth Embodiment)] In previous embodiments, an example has been given in which the longitudinal direction of each groove 15 and each protrusion 16 is inclined with respect to the circumferential direction of the tire, but the invention is not limited to this embodiment. Figure 7 is a front view of the buttress surface 13 including the grooves 15 and protrusion 16 of an embodiment of the present disclosure.

[0053] In this embodiment, the longitudinal direction of each groove 15 and each protrusion 16 is set parallel to the circumferential direction of the tire. With such a tire 1, the distortion of the buttress portion 5 that occurs during tire rotation is suppressed to increase in the groove 15 sandwiched between the pair of protrusions 16, 16, and handling stability on dry road surfaces is maintained.

[0054] Although particularly preferred embodiments of this disclosure have been described in detail above, this disclosure is not limited to the illustrated embodiments and can be modified and implemented in various ways. [Examples]

[0055] [Example A] A prototype tire was manufactured (Examples 1-7) having the basic structure shown in Figure 1 and multiple grooves and multiple protrusions based on the specifications in Table 1. In Examples 1-5, the longitudinal angles θ1 of the grooves and protrusions are different from each other. In Example 6, as shown in Figure 6, each groove and each protrusion is bent with respect to the tire radial direction in a front view of the buttress surface. In Example 7, as shown in Figure 7, the longitudinal direction of each groove and each protrusion is set parallel to the tire circumferential direction.

[0056] For comparison, prototype tires were manufactured in which the buttress surface lacked grooves and protrusions, and only recesses were provided on the buttress surface, as shown in Figure 8 (Comparative Example 1), and in which only grooves were provided (Comparative Example 2).

[0057] Each prototype tire was then evaluated for its handling stability on dry surfaces and its performance on snow. The specifications of each tire were identical except for the configuration shown in Table 1, and the tire sizes were as follows. The test method was also described below. The test results are shown in Table 1. Tire size: 195 / 65R15 Rim size: 15 x 6.5 internal pressure: Front tire: 250kPa Rear tire: 240kPa Vehicle: Passenger car (domestic hybrid vehicle) Tire mounting position: All wheels Groove: Maximum depth H3: 1.0 mm Maximum groove width W3m: 5.0mm Convex stripe: Maximum height H4: 1.0mm Maximum width W4m: 5.0mm Total volume of grooves V1 / Total volume of raised grooves V2: 0.8 (Examples 1-7)

[0058] <Handling stability on dry surfaces> The handling stability of the above vehicles when driven on dry roads was evaluated subjectively by the drivers. The results are scored with Comparative Example 1 set to 100, and a higher number indicates better handling stability on dry roads. A score of 95 or higher is acceptable, and a score of 98 or higher is more desirable.

[0059] <Snow performance> The traction performance of the above vehicles when driving on snowy roads was evaluated subjectively by the drivers. The results are scored with Comparative Example 1 set to 100, and a higher number indicates better snow performance. A score of 95 or higher is acceptable, and a score of 98 or higher is more desirable. The test results are shown in Table 1.

[0060] [Table 1]

[0061] The test results showed that the examples could improve snow performance compared to Comparative Examples 1 and 2, and also improve handling stability on dry surfaces compared to Comparative Example 2. Furthermore, Examples 2 to 4, in which the angle θ1 was set within the preferred range, were able to improve both handling stability on dry surfaces and snow performance in a well-balanced manner compared to Examples 1 and 5, in which the angle θ1 was set outside the preferred range.

[0062] [Example B] A prototype tire was fabricated having the basic structure shown in Figure 1 and multiple grooves and multiple ridges based on the specifications in Table 2 (Examples 3, 8-11). In Examples 3, 8-11, the ratio V1 / V2 of the total volume V1 of the grooves to the total volume V2 of the ridges is different for each example.

[0063] The handling stability on dry surfaces and the performance on snow were evaluated for each prototype tire. The specifications of each tire were identical except for the configuration shown in Table 2, and the tire size, etc., were the same as in Example A, except as noted below. The test method was also the same as in Example A. The test results are shown in Table 2. Front view of the buttress surface: Figure 3 Longitudinal angle θ1 (degrees) of grooves and protrusions: 45 degrees

[0064] [Table 2]

[0065] The test results showed that the examples could improve snow performance compared to Comparative Examples 1 and 2 of Example A, and also improve handling stability on dry surfaces compared to Comparative Example 2. Furthermore, Examples 3, 9, and 10, in which the ratio V1 / V2 of the total volume of grooves V1 to the total volume of raised grooves V2 was set to a preferred range, were able to improve both handling stability on dry surfaces and snow performance in a well-balanced manner compared to the other examples.

[0066] [Example C] A prototype tire was manufactured having the basic structure shown in Figure 1 and multiple grooves and multiple ridges based on the specifications in Table 3 (Examples 3, 12-19). In Examples 3, 12-19, the maximum depth H3 and maximum groove width W3m of the grooves, and the maximum height H4 and maximum width W4m of the ridges differ from each other.

[0067] The handling stability on dry surfaces and the performance on snow were evaluated for each prototype tire. The specifications of each tire were identical except for the configuration shown in Table 3, and the tire size, etc., were the same as in Example A, except as noted below. The test method was also the same as in Example A. The test results are shown in Table 3. Front view of the buttress surface: Figure 3 Longitudinal angle θ1 (degrees) of grooves and protrusions: 45 degrees

[0068] [Table 3]

[0069] The test results showed that the examples could improve snow performance compared to Comparative Examples 1 and 2 of Example A, and also improve handling stability on dry surfaces compared to Comparative Example 2. Furthermore, Examples 3, 13, 14, 17, and 18, in which the maximum groove depth H3 and maximum groove width W3m, and the maximum ridge height H4 and maximum ridge width W4m were set within a preferred range, were able to improve both handling stability on dry surfaces and snow performance in a well-balanced manner compared to the other examples.

[0070] [Note] This disclosure includes the following aspects.

[0071] [Disclosure 1] A tire having a buttress surface extending radially inward from the tread contact edge, A plurality of grooves are recessed inward from the buttress surface and extend along the buttress surface, It has a plurality of protrusions that project outward from the buttress surface and extend along the buttress surface, The grooves and protrusions are arranged alternately. tire. [Disclosure 2] The tire according to Disclosure 1, wherein the longitudinal direction of each groove and each protrusion is inclined with respect to the circumferential direction of the tire. [Disclosure 3] The tire according to Disclosure 2, wherein the angle of the longitudinal direction with respect to the circumferential direction of the tire is 20 to 70 degrees. [Disclosure 4] The tire according to disclosure 2 or 3, wherein each of the grooves and protrusions is bent with respect to the tire radius direction in a front view of the buttress surface. [Disclosure 5] The tire according to Disclosure 1, wherein the longitudinal direction of each groove and each protrusion is parallel to the circumferential direction of the tire. [Disclosure 6] The tire according to any one of disclosures 1 to 5, wherein the ratio V1 / V2 of the total volume V1 of the multiple grooves to the total volume V2 of the multiple protrusions is 0.7 to 1.3. [Disclosure 7] The tire according to any one of disclosures 1 to 6, wherein the total volume V1 of the plurality of grooves is less than the total volume V2 of the plurality of protrusions. [Explanation of Symbols]

[0072] 1 tire 13 Buttress surfaces 15 grooves 16 convex stripes

Claims

1. A tire having a buttress surface extending radially inward from the tread contact edge, A plurality of grooves are recessed inward from the buttress surface and extend along the buttress surface, It has a plurality of protrusions that project outward from the buttress surface and extend along the buttress surface, The grooves and protrusions are arranged alternately. The ratio V1 / V2 of the total volume V1 of the multiple grooves to the total volume V2 of the multiple protrusions is 0.7 to 1.

3. A protruding portion is provided that extends from the buttress surface, The inner end of the protruding portion in the radial direction of the tire terminates without reaching the grooves and protrusions. The aforementioned protruding portions are spaced apart in the circumferential direction of the tire. tire.

2. The tire according to claim 1, wherein the longitudinal direction of each groove and each protrusion is inclined with respect to the circumferential direction of the tire.

3. The tire according to claim 2, wherein the angle of the longitudinal direction with respect to the circumferential direction of the tire is 20 to 70 degrees.

4. The tire according to claim 2 or 3, wherein each of the grooves and protrusions is bent with respect to the tire radius direction in a front view of the buttress surface.

5. The tire according to claim 1, wherein the longitudinal direction of each groove and each protrusion is parallel to the circumferential direction of the tire.

6. The tire according to any one of claims 1 to 5, wherein the total volume V1 of the plurality of grooves is less than the total volume V2 of the plurality of protrusions.

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