JP7127521B2 - pneumatic tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire provided with a plurality of protectors on a buttress portion.

Patent Literature 1 listed below describes a pneumatic tire provided with protrusions that protrude from a buttress surface and are arranged in the circumferential direction. Such a pneumatic tire improves lateral grip performance on snowy roads, and thus has high on-snow performance. Each of the protrusions is located between outer lateral grooves adjacent to each other in the tire circumferential direction.

JP 2013-038314 A

By the way, in order to improve the noise performance of a tire, a so-called "variable pitch" is widely used, in which the interval in the tire circumferential direction of the lateral grooves provided in the tread portion is randomly changed. In a tire adopting the variable pitch, there is a demand, for example, to change the length of each protrusion in the tire circumferential direction in relation to the interval between the lateral grooves in order to improve the appearance of the buttress surface. In addition, even in tires that do not adopt the variable pitch, there is a demand to gradually change the length of each protrusion in the tire circumferential direction to give a change and unexpectedness to the appearance of the buttress portion. .

On the other hand, when the lengths of the protrusions in the tire circumferential direction are different, the volumes of the protrusions are different, and the masses of the protrusions are also different. Therefore, in such a tire, there is a problem that the uniformity of the tire is poor, such as different centrifugal forces acting on the protrusions during rolling.

The present invention has been devised in view of the problems described above, and a main object of the present invention is to provide a pneumatic tire having excellent uniformity.

The present invention is a pneumatic tire comprising a tread portion and a pair of buttress portions extending radially inward from both axial ends of the tread portion, wherein at least one of the pair of buttress portions includes: A protector row is formed, and in the protector row, pattern units including protectors protruding outward in the tire axial direction are arranged in the tire circumferential direction, and the pattern unit is the length in the tire circumferential direction. The protectors of the plurality of types of pattern units include a plurality of types with different pitches, and have substantially the same protector volume.

In the pneumatic tire according to the present invention, the protectors of the plurality of types of pattern units include bases and recesses recessed from the bases, and the recesses are arranged such that the respective protector volumes are substantially the same. preferably have different volumes.

In the pneumatic tire according to the present invention, it is preferable that the protectors of the plurality of types of pattern units have different raised heights so that the respective protector volumes are substantially the same.

In the pneumatic tire according to the present invention, the tread portion includes a tread pattern row, and the tread pattern row includes tread pattern units including land portions arranged in the tire circumferential direction, and the tread pattern units are: The plurality of types of protectors in the protector row are arranged in accordance with the arrangement of the plurality of types of tread pattern units in the tread pattern row. is desirable.

In the pneumatic tire according to the present invention, it is preferable that the protectors of the plurality of types of pattern units have substantially the same length in the tire radial direction.

In the pneumatic tire according to the present invention, it is preferable that the raised height of the protector of the plurality of types of pattern units is 3 to 8 mm.

In the pneumatic tire according to the present invention, the protectors of the plurality of types of pattern units include first portions each having substantially the same raised height, and raised heights smaller than the first portions and raised. and second portions, each having a different height.

In the pneumatic tire according to the present invention, it is preferable that the second portion be arranged radially outward of the first portion.

In the pneumatic tire according to the present invention, the first portion preferably has a length in the tire radial direction of 5 to 10 mm.

In the pneumatic tire according to the present invention, the protectors of the plurality of types of pattern units have a third portion having a raised height larger than that of the second portion and having substantially the same raised height. preferably included.

In the pneumatic tire according to the present invention, it is preferable that the third portion be arranged radially outward of the second portion.

In the pneumatic tire according to the present invention, the first portion includes a main portion having a maximum raised height, and a gradually decreasing portion connected to the main portion and having a raised height that gradually decreases toward the second portion. is desirable.

In the pneumatic tire according to the present invention, it is preferable that the gradually decreasing portion has an inclined surface that is inclined with respect to the height direction, and that the angle of the inclined surface with respect to the height direction is 15 degrees or more.

In the pneumatic tire according to the present invention, the main portion has an outward surface facing outward in the tire axial direction, and the inclined surface is an arc portion that is continuous with the outward surface and projects outward in the tire axial direction. It is desirable to have

In the pneumatic tire according to the present invention, the arc portion preferably has a radius of curvature of 2.0 mm or more.

In the pneumatic tire of the present invention, a protector row is formed in the buttress portion. In the protector row, pattern units including protectors protruding outward in the tire axial direction are arranged in the tire circumferential direction, and the pattern units include a plurality of types with different pitches, which are lengths in the tire circumferential direction. there is The protectors of the plurality of types of pattern units have substantially the same protector volume. Therefore, for example, when running on tires, the centrifugal forces of the protectors are substantially the same, resulting in excellent uniformity.

1 is a cross-sectional view showing an embodiment of a pneumatic tire of the present invention; FIG. Figure 2 is an enlarged side view of the tire of Figure 1; It is a perspective view of a protector. FIG. 11 is a perspective view of a protector of another embodiment; FIG. 5 is a cross-sectional view taken along line AA of FIG. 4; FIG. 11 is a perspective view of a protector of still another embodiment; FIG. 7 is a cross-sectional view taken along line BB of FIG. 6;

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a meridian cross-sectional view of the right half of a pneumatic tire (hereinafter sometimes simply referred to as "tire") 1 of the present embodiment, including a tire rotation axis (not shown) in a normal state. FIG. 1 shows an all-season tire for passenger cars as a preferred embodiment. However, the present invention is also applicable to other categories of tires 1, including light truck and heavy duty tires.

The "normal state" is a no-load state in which the tire 1 is mounted on a normal rim (not shown) and filled with a normal internal pressure. In this specification, unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in this normal state.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire 1 is based. Then it is "Measuring Rim".

"Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standard that Tire 1 is based on. Maximum value described in VARIOUSCOLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

Inside the tire 1 of this embodiment, ties such as a carcass 6 and a belt layer 7 and structural members are arranged. Known aspects are appropriately adopted for these tire constituent members.

The tire 1 of this embodiment includes a tread portion 2 and a pair of buttress portions 5 extending inward in the tire radial direction from both ends 2t of the tread portion 2 in the tire axial direction. Both ends 2t of the tread portion 2 are defined as the outermost contact points in the tire axial direction when the tire 1 in a normal state is applied with a normal load and is grounded on a flat surface with a camber angle of 0 degrees. Hereinafter, in this specification, both ends 2t of the tread portion 2 may be referred to as tread ends 2t.

The above-mentioned "regular load" is the load specified for each tire by the above-mentioned standard. Value, "LOAD CAPACITY" for ETRTO.

A protector row 8 is formed on at least one of the pair of buttress portions 5 . The protector row 8 is provided, for example, on each of the pair of buttress portions 5 .

The protector row 8 of the present embodiment is formed by arranging pattern units 9 including protectors 10 protruding outward in the axial direction of the tire, arranged in the circumferential direction of the tire. The protector 10 protrudes outward in the tire axial direction from the outer surface 5a of the buttress portion 5 in this embodiment. In this specification, the outer surface 5a of the buttress portion 5 means a reference surface that smoothly extends from the tread edge 2t in a normal state except for local unevenness including embossed marks such as emblems and uneven patterns. . In this embodiment, the outer surface 5a of the buttress portion 5 is smoothly connected to the outer surface 3a of the sidewall portion 3 arranged radially inward of the buttress portion 5 .

FIG. 2 is a side view of the tire 1 and an enlarged view of the buttress portion 5. FIG. As shown in FIG. 2, in this embodiment, the pattern unit 9 is formed by a protector 10 and a smooth outer surface 5a arranged between the protector 10 and the protector 10 adjacent in the tire circumferential direction. .

The pattern units 9 of this embodiment include a plurality of types with different pitches P, which are lengths in the tire circumferential direction. The pattern units 9 of this embodiment are composed of a first pattern unit 9A, a second pattern unit 9B and a third pattern unit 9C in descending order of pitch P, and are formed with three types of pitches P1 to P3. As described above, the protector row 8 of the present embodiment is formed by arranging one pattern group 11 including the first pattern units 9A to the third pattern units 9C in the tire circumferential direction. The pattern group 11 of the present embodiment is formed by arranging the third pattern unit 9C, the first pattern unit 9A, and the second pattern unit 9B in this order from the left. The pitch P of the pattern unit 9 is not particularly limited as long as it is two or more types, but three or five types, for example, are preferably adopted. Also, the arrangement order of the pitches P1 to P3 of the pattern group 11 is not limited to that of the present embodiment.

The protectors 10 of the plurality of types of pattern units 9 have substantially the same protector volume. Such a tire 1 has excellent uniformity, for example, the centrifugal force of each protector 10 becomes substantially the same during tire running. The "substantially the same" mentioned above takes into consideration molding errors and the like due to vulcanization molding of the protector 10 with a mold. In this sense, even if at least two types of protectors 10 have different protector volumes, if the difference is within ±5% of one protector volume, they are considered to be substantially the same. The protector volume is the volume outside the outer surface 5a of the buttress portion 5 in the axial direction of the tire.

FIG. 3 is a perspective view of the protector 10 of this embodiment. As shown in FIG. 3 , the protector 10 of this embodiment includes a base 13 and a recess 14 recessed from the base 13 .

In this embodiment, the protectors 10 of the plurality of types of pattern units 9 are formed with different volumes of recesses 14 so that the respective protector volumes are substantially the same. Thereby, for example, even when the circumferential length L (shown in FIG. 2) of each protector 10 is different, the protector volume can be made substantially the same. The volume of the recessed portion 14 is obtained by burying the axially inner portion of the base portion 13, which has a raised height (maximum raised height) h1 (shown in FIG. 1). The recess 14 is a portion having a depth d greater than 70% of the raised height h1 of the base 13 .

Each base portion 13 of each protector 10 is formed in a substantially H shape including a pair of radial portions 18 , 18 and a circumferential portion 19 in this embodiment. In this embodiment, the radial portions 18 are arranged on both sides in the tire circumferential direction, and have a length in the tire radial direction that is greater than a length in the tire circumferential direction. In this embodiment, the circumferential portion 19 connects between the radial portions 18 and 18 and is formed to have a length in the tire circumferential direction larger than a length in the tire radial direction. The shape of the base 13 is not limited to such an aspect.

The recessed portion 14 of the present embodiment includes, for example, a first recessed portion 16 and a second recessed portion 17 arranged radially inward of the first recessed portion 16 . In order to make the protector volume of each protector 10 substantially the same, both the first recess 16 and the second recess 17 or one of the recesses 16 and 17 can be made different in volume. . In this embodiment, the protector volumes of the protectors 10 are made substantially the same by varying the volumes of the first recesses 16 .

Although not particularly limited, the volume of the first recess 16 is preferably about 15% to 50% of the protector volume of the protector 10 in which the first recess 16 is provided. The volume of the first recess 16 is formed larger than the volume of the second recess 17, for example.

The first recess 16 and the second recess 17 are each surrounded by a pair of radial portions 18 , 18 and a circumferential portion 19 in this embodiment. The first recessed portion 16 is adjacent to the circumferential portion 19 radially outwardly of the tire. The second recessed portion 17 is adjacent to the circumferential portion 19 on the inner side in the tire radial direction. The first recessed portion 16 and the second recessed portion 17 are arranged, for example, at intermediate positions in the tire circumferential direction of the protector 10 . Such first recessed portion 16 and second recessed portion 17 exhibit great traction on muddy ground.

As shown in FIG. 1, the depth d1 of the first recess 16 is formed smaller than the depth d2 of the second recess 17, for example. As a result, the rigidity of the outer portion of the protector 10 in the tire radial direction, which is more likely to come into contact with the road surface, is maintained high. The depth of the recess 14 is measured from the position where the base 13 has the maximum raised height.

It is desirable that the raised height h1 of the base portion 13 of the protector 10 of the plurality of types of pattern units 9 is 3 to 8 mm. If the protrusion height h1 is 3 mm or less, the protector 10 becomes difficult to see, and the appearance of the buttress portion 5 may deteriorate. If the height h1 of the protrusion exceeds 8 mm, the mass of the protector 10 becomes large, which may adversely affect the radial fore variation (RFV) and radial runout (RRO) and deteriorate the uniformity.

It is desirable that the protectors 10 of the plurality of types of pattern units 9 have substantially the same length La in the tire radial direction. As a result, the centrifugal forces of the protectors 10 can be further uniformed, and the uniformity can be further improved. The "substantially the same" mentioned above takes into consideration molding errors and the like due to vulcanization molding of the protector 10 with a mold. In this sense, even if the lengths La of at least two types of protectors 10 in the tire radial direction are different, if the difference is within ±10% of the length La of one protector 10 in the tire radial direction, substantially shall be included in the same

Although the length La of the protector 10 in the tire radial direction is not particularly limited, it is preferably 15% to 35% of the tire section height H, for example. Such a protector 10 effectively improves the appearance of the buttress portion 5 . In order to effectively exhibit such an action, the inner end 10i in the tire radial direction of the protector 10 is positioned radially outwardly from the bead base line BL by 50% to 70% of the tire section height H. It is desirable to arrange at the tire radial distance Ha. The bead baseline BL is a tire axial line passing through the rim diameter defined by the JATMA standard.

It is desirable that the protectors 10 of the plurality of types of pattern units 9 have substantially the same distance Ht in the tire radial direction from the bead base line BL to the center of gravity Ga. As a result, the centrifugal forces of the protectors 10 can be evened out, and the uniformity can be further improved. The "substantially the same" mentioned above takes into consideration molding errors and the like due to vulcanization molding of the protector 10 with a mold. In this sense, even if the distance Ht in the tire radial direction of the center of gravity Ga of at least two types of protectors 10 is different, if the difference in the distance in the tire radial direction between the two is within 10 mm, they are substantially the same.

As shown in FIG. 3, each protector 10 includes a plurality of side surfaces 20A extending axially outward from the outer surface 5a and an outward surface 20B facing axially outward. The outward surface 20B and the side surface 20A are connected via an edge 21, for example. Side 20A may include, for example, a gently sloping chamfer 22 to increase the rigidity of base 13 .

The edge 21 of this embodiment includes a pair of circumferential edges 21A extending in the tire circumferential direction, and a pair of radial edges 21B extending in the tire radial direction connecting between both ends of the circumferential edges 21A. In this embodiment, the pair of circumferential edges 21A has an inner edge 21a arranged radially inward of the tire and an outer edge 21b arranged radially outward of the inner edge 21a. The inner edge 21a of this embodiment is formed to have a larger length in the tire circumferential direction than the outer edge 21b. In the present embodiment, the pair of radial edges 21B linearly extend while being inclined toward the radially inner side of the tire so as to separate from each other. The protector 10 of the present embodiment is formed in an isosceles trapezoidal shape that is substantially symmetrical with respect to a tire radial direction line 10c passing through the middle position in the tire circumferential direction. In addition, the protector 10 is not limited to such an aspect, and various shapes can be adopted.

The protectors 10 of the plurality of types of pattern units 9 may have different raised heights h1 of the bases 13, for example, so that the protector volumes are substantially the same. Uniformity can be improved in such a mode as well. In addition, the protectors 10 of the plurality of types of pattern units 9 may have different protrusion heights h1 and recessed portions 14 volumes, for example, so that the protector volumes are substantially the same.

As shown in FIG. 2, the ratio of the pitch P of the pattern unit 9 and the length L of the protector 10 arranged in the pattern unit 9 in the tire circumferential direction (hereinafter simply referred to as "protector pitch ratio (L/P )” is desirably substantially the same for each of the pattern units 9 . This further enhances the appearance of the buttress portion 5 . That is, the protector pitch ratio (L1/P1) of the first pattern unit 9A, the protector pitch ratio (L2/P2) of the second pattern unit 9B, and the protector pitch ratio (L3/P3) of the third pattern unit 9C are Preferably, they are substantially identical. The "substantially the same" mentioned above takes into consideration molding errors and the like due to vulcanization molding of the protector 10 with a mold. In this sense, even if at least two types of protector pitch ratios (L/P) are different, if the difference is within ±0.1 when the protector pitch ratio (L/P) is expressed by a decimal number, it is substantially shall be included in the same

The tread portion 2 comprises tread pattern rows 25 in this embodiment. The tread pattern row 25 of the present embodiment is formed by arranging tread pattern units 27 including land portions 26 in the tire circumferential direction. The tread portion 2 includes, for example, a plurality of lateral grooves G that communicate with the tread end 2t and are arranged in the tire circumferential direction, and a plurality of land portions (blocks) 26 that are formed between the lateral grooves G adjacent to each other in the tire circumferential direction. and Thus, the tread pattern unit 27 of this embodiment is formed by the land portion 26 and the lateral grooves G. As shown in FIG.

The tread pattern unit 27 includes, for example, a plurality of types with different pitches T, which are lengths in the tire circumferential direction. In the present embodiment, the tread pattern unit 27 consists of a first tread pattern unit 27A, a second tread pattern unit 27B and a third tread pattern unit 27C in descending order of pitch T, with three pitches T1 to T3. formed. Thus, in the tire 1 of this embodiment, the pitches T of the tread pattern units 27 are the same as the pitches P of the pattern units 9, and there are three types.

The tread pattern row 25 is formed by, for example, forming one tread pattern group 28 including first tread pattern units 27A to third tread pattern units 27C arranged side by side in the tire circumferential direction. The pitch T of the tread pattern unit 27 is not limited to such a mode, and may be one type of pitch T or a plurality of types different from the number of pitches P of the pattern unit 9 .

In this embodiment, the plurality of types of pattern units 9 in the protector row 8 are arranged in accordance with the arrangement of the plurality of types of tread pattern units 27 in the tread pattern row 25 . That is, the tread pattern group 28 of this embodiment is formed by arranging the third tread pattern unit 27C, the first tread pattern unit 27A, and the second tread pattern unit 27B in order from the left side. This further enhances the appearance of the buttress portion 5 and the tread portion 2 .

The ratio (W/T) between the pitch T of the tread pattern unit 27 and the length W of the land portion 26 of the tread pattern unit 27 in the tire circumferential direction is substantially the same for each of the tread pattern units 27. is desirable. As a result, the appearance of the tread portion 2 is further improved, and in turn the appearance of the buttress portion 5 adjacent to the tread portion 2 is also improved. The tread pitch ratio (W1/T1) of the first tread pattern unit 27A, the tread pitch ratio (W2/T2) of the second tread pattern unit 27B, and the tread pitch ratio (W3/T3) of the third tread pattern unit 27C are , are preferably substantially identical to each other. The above-mentioned "substantially the same" takes into consideration molding errors and the like due to vulcanization molding of the land portion 26 with a mold. In this sense, even if at least two types of tread pitch ratio (W / T) are different, if the tread pitch ratio (W / T) is expressed by a decimal number, if the difference is within ± 0.1, substantially shall be included in the same.

In the tire 1 of this embodiment, the first tread pattern unit 27A is arranged outside the first pattern unit 9A in the tire radial direction. In addition, in the tire 1 of the present embodiment, the second tread pattern unit 27B is arranged outside the second pattern unit 9B in the tire radial direction, and the third tread pattern unit 27C is arranged outside the third pattern unit 9C in the tire radial direction. is distributed. As a result, the effect of improving the appearance described above is effectively exhibited.

The pattern unit 9 and the tread pattern unit 27 are not limited to being arranged in this way. good. Also, the arrangement of the tread pattern group 28 and the arrangement of the pattern group 11 may be different. When the tire circumferential distance (not shown) between the centers of gravity Ga of the protectors 10 adjacent to each other in the tire circumferential direction is the same, the uniformity is further improved.

FIG. 4 is a perspective view of protector 10 of another embodiment, and FIG. 5 is a cross-sectional view taken along line AA of FIG. Components that are the same as those of this embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and descriptions thereof are omitted. As shown in FIGS. 4 and 5, in this embodiment, the protectors 10 of the plurality of types of pattern units 9 each include a base portion 13 including a first portion 30 and a second portion 31 . The first portion 30 of this embodiment is formed such that the raised height h2 is substantially the same in each protector 10 of the pattern unit 9 . The second portion 31 of the present embodiment has a height h3 smaller than that of the first portion 30, and the protectors 10 of the pattern unit 9 have different heights h3. Thus, the protectors 10 of the plurality of types of pattern units 9 of this embodiment are formed so that the respective protector volumes are substantially the same. Also in this embodiment, the volumes of the respective recesses 14 or the raised heights h2 of the first portions 30 may be varied so that the protector volumes are substantially the same.

The first portion 30, in this embodiment, has an inner portion 34 including an inner edge 21a and a pair of side portions 35, 35 each including a pair of circumferential edges 21A. The second portion 31, in this embodiment, is surrounded by the first portion 30 and includes an outer edge 21b. Such a second portion 31 cooperates with the first recess 16 of the recess 14 to enhance traction on muddy ground.

The second portion 31 is arranged, for example, outside the first portion 30 in the tire radial direction. As a result, in a general tire shape, the rigidity of the tire radially inner portion of the protector 10 arranged on the outer side in the tire axial direction is ensured, for example, contact with projections such as rubble protruding from the slope of the rut. It is possible to suppress cracking and chipping of the protector 10 due to. In this embodiment, the second portion 31 is adjacent to the inner portion 34 radially outwardly of the tire.

As shown in FIG. 5, the length Lb of the first portion 30 in the tire radial direction is preferably 5-10 mm. If the length Lb of the first portion 30 is less than 5 mm, the effect of suppressing cracking or chipping of the protector 10 due to contact with the protrusions may be reduced. Also, if the length Lb of the first portion 30 exceeds 10 mm, the appearance of the buttress portion 5 may deteriorate. The length Lb of the first portion 30 in the tire radial direction is the width of the inner portion 34 in the tire radial direction. Note that the first portion 30 and the second portion 31 are not limited to such an aspect, and can take various aspects.

Although not particularly limited, the height h2 of the protrusion of the first portion 30 is preferably about 3 to 8 mm. Thereby, the appearance performance and uniformity of the buttress portion 5 are improved in a well-balanced manner. The raised height h3 of the second portion 31 is set, for example, so that the protector volumes are substantially the same, preferably 2 to 7 mm.

The first portion 30 includes a main portion 37 having a maximum raised height h2 and a gradually decreasing portion 38 connected to the main portion 37 and having a gradually reduced raised height h2 toward the second portion 31 . As a result, since the difference in rigidity between the first portion 30 and the second portion 31 is reduced, cracking and chipping of the protector 10 are further suppressed, and the uniformity of the tire 1 is maintained at a high level until the end of use.

In the tire meridian cross section, the tapering portion 38 has an inclined surface 39 that is inclined with respect to the height direction of the bump in this embodiment. In this embodiment, the main portion 37 and the second portion 31 respectively have outer side surfaces 40a and 40b facing outward in the tire axial direction. The inclined surface 39 of this embodiment continues to the outer surface 40 a of the main portion 37 and the outer surface 40 b of the second portion 31 .

In this embodiment, the inclined surface 39 has an arc portion 39a that is continuous with the outer side surface 40a of the main portion 37 and protrudes outward in the tire axial direction. Such arc portions 39 a further reduce the rigidity step of the main portion 37 of the protector 10 , thereby suppressing cracks and chipping of the protector 10 . Also, the inclined surface 39 has an arc portion 39b that is contiguous with the outer side surface 40b of the second portion 31 and concaves inward in the tire axial direction. In order to effectively exhibit the above effects, it is desirable that the curvature radius r of each of the circular arc portions 39a and 39b is 2.0 mm or more.

From the same point of view, it is desirable that the angle θ of the inclined surface 39 with respect to the raised height direction is 15 degrees or more. From the viewpoint of keeping the appearance of the buttress portion 5 high, the angle θ is desirably 60 degrees or less.

FIG. 6 is a perspective view of protector 10 of still another embodiment, and FIG. 7 is a cross-sectional view taken along line BB of FIG. Components that are the same as those of the embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and descriptions thereof are omitted. As shown in FIGS. 6 and 7, in this embodiment, the protectors 10 of the plurality of types of pattern units 9 each include a base portion 13 including a first portion 30, a second portion 31 and a third portion 32. there is The third portion 32 of the present embodiment has a height h4 greater than that of the second portion 31, and is formed such that the height h4 of the protrusions is substantially the same in each protector 10 of the pattern unit 9. there is The protectors 10 of the plurality of types of pattern units 9 of this embodiment have substantially the same protector volume by varying the raised height h3 of the second portion 31 and the volume of the first recessed portion 16 respectively. It is formed to be At least one of the heights h2 to h4 of the first to third portions 30 to 32 or the volume of the recess 14 may be different so that the respective protector volumes are substantially the same.

The third portion 32 is arranged radially outward of the second portion 31 . Since the third portion 32 is arranged at a position close to the road surface in this manner, cracking or chipping of the protector 10 due to projections such as rubble placed on the road surface is further suppressed.

The length Lc of the third portion 32 in the tire radial direction is preferably 30% to 40% of the length La of the protector 10 in the tire radial direction. Such a third portion 32 enhances the rigidity of the protector 10, suppresses chipping and cracking of the protector 10, and ensures excellent uniformity over a long period of time.

The raised height h4 of the third portion 32 is the same as the raised height h2 of the first portion 30 in this embodiment. As a result, the effect of maintaining the appearance and uniformity of the buttress portion 5 at a high level is exhibited. The base 13 of this embodiment is formed with a second portion 31 surrounded by a first portion 30 and a third portion 32 .

The protector 10 of this embodiment has a pair of radial portions 18 , 18 and a circumferential portion 19 like the protector 10 of this embodiment. The circumferential portion 19 is formed by a first portion 30 and a second portion 31 in this embodiment. Each radial portion 18 is formed in this embodiment by a first portion 30 , a second portion 31 and a third portion 32 . Further, in this embodiment, the first recessed portion 16 is sandwiched between the outer portion 16A whose both sides in the tire circumferential direction are sandwiched between the third portions 32, and the second portion 31 adjacent to the outer portion 16A on the inner side in the tire radial direction. and an inner portion 16B.

Although the particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified in various ways.

Tires having the basic structure shown in FIG. 1 and the buttress portion shown in FIG. 2 were manufactured, and their uniformity, cut resistance, traction and appearance were evaluated. Common specifications are as follows. In Comparative Example 1, the first recesses of all protectors have the same volume, and protectors adjacent to each other in the tire circumferential direction have different protector volumes. In Example 1, the volumes of the first recesses are different so that the protector volumes of the protectors are substantially the same. In Examples 2 and 3, the volume of the first recess and the raised height of the second portion are different so that the protector volume of each protector is substantially the same.
The raised height of each protector in Comparative Example 1 and Examples 1 to 3 is 8 mm, and the height positions of the centers of gravity of the protectors in the radial direction of the tire are aligned.
Tire size: 275/65R18
Rim: 8.0J (ETRTO standard)
The test method is as follows.

<Uniformity>
Using a tire uniformity tester, radial force variation (RFV), dynamic balance (DB) and static balance (SB) were measured under the following conditions, and indicated as an index with Comparative Example 1 being 100. The smaller the numerical value, the better.
Internal pressure: 205kPa
Load: 8.0kN
Speed: 10km/h

<Traction performance>
Each test tire was mounted on all wheels of a four-wheel drive vehicle with a displacement of 3500 cc. Then, a test driver ran the vehicle on a muddy test course, and the running characteristics regarding traction at this time were evaluated by the test driver's senses. The results are indicated by a score with Comparative Example 1 being 100. The higher the number, the better the traction performance.
Internal pressure: 205kPa

<Cut resistance performance>
After running the above vehicle on a rocky road surface containing rocks and debris for about 1,500 km, the depth and length of the cut scratches on the outer surface of the buttress part were examined by a test driver. The cutting performance was evaluated. The results are indicated by a score with Comparative Example 1 being 100. The larger the numerical value, the better the cut resistance performance.

<Appearance performance>
The appearance of the buttress portion of the sample tire in the normal state was visually evaluated by a tester. Results are indicated as good or bad.

<Tire mass>
The mass of each sample tire was measured. Results are shown as actual measurements.
The results of the tests are shown in Table 1.

As a result of the test, it was confirmed that the tire of the example was improved in various performances, especially the uniformity, as compared with the tire of the comparative example.

REFERENCE SIGNS LIST 1 pneumatic tire 2 tread portion 5 buttress portion 8 protector row 9 pattern unit 10 protector P pitch

Claims (15)

A pneumatic tire,
A tread portion and a pair of buttress portions extending radially inward from both ends of the tread portion in the tire axial direction,
A protector row is formed on at least one of the pair of buttress portions,
In the protector row, pattern units including protectors protruding outward in the axial direction of the tire are arranged in the circumferential direction of the tire,
The pattern unit includes a plurality of types with different pitches, which are lengths in the tire circumferential direction,
The protectors of the plurality of types of pattern units have substantially the same protector volume.
pneumatic tires. Each of the protectors of the plurality of types of pattern units includes a base and a recess recessed from the base, and the recesses have different volumes such that the protector volumes are substantially the same. The pneumatic tire according to claim 1. The pneumatic tire according to claim 1 or 2, wherein the protectors of the plurality of types of pattern units have different raised heights so that the respective protector volumes are substantially the same. The tread portion includes tread pattern rows,
In the tread pattern row, tread pattern units including land portions are arranged in the tire circumferential direction,
The tread pattern unit includes a plurality of types with different pitches, which are lengths in the tire circumferential direction,
The pneumatic tire according to any one of claims 1 to 3, wherein the plurality of types of protectors in the protector row are arranged in accordance with the arrangement of the plurality of types of tread pattern units in the tread pattern row. The pneumatic tire according to any one of claims 1 to 4, wherein the protectors of the plurality of types of pattern units have substantially the same length in the tire radial direction. The pneumatic tire according to any one of claims 1 to 5, wherein the raised height of the protector of the plurality of types of pattern units is 3 to 8 mm. The protectors of the plurality of types of pattern units include first portions each having substantially the same raised height, and second portions each having a smaller raised height than the first portion and different raised heights. The pneumatic tire according to any one of claims 1 to 4, comprising: The pneumatic tire according to claim 7, wherein the second portion is arranged radially outward of the first portion. The pneumatic tire according to claim 7 or 8, wherein the first portion has a length in the tire radial direction of 5 to 10 mm. 10. The protector according to any one of claims 7 to 9, wherein said protector of said plurality of types of pattern units further includes a third portion having a raised height greater than said second portion and having substantially the same raised height. The pneumatic tire described in The pneumatic tire according to claim 10, wherein the third portion is arranged radially outward of the second portion. 12. The first portion according to any one of claims 7 to 11, wherein said first portion includes a main portion having a maximum raised height and a gradually decreasing portion which continues to said main portion and whose raised height gradually decreases toward said second portion. The pneumatic tire described in . The gradually decreasing portion has an inclined surface that is inclined with respect to the height direction of the protrusion,
13. The pneumatic tire according to claim 12, wherein the angle of the inclined surface with respect to the height direction of the protrusion is 15 degrees or more. The main portion has an outward surface facing outward in the axial direction of the tire,
14. The pneumatic tire according to claim 13, wherein the inclined surface has an arcuate portion that is contiguous with the outward surface and protrudes outward in the tire axial direction. The pneumatic tire according to claim 14, wherein the arc portion has a radius of curvature of 2.0 mm or more.

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