Pneumatic tire

In a pneumatic tire, at least one of plurality of projecting portions includes at least one opening. At least one of the projecting portions is divided into an inner region placed on the inner side in a tire radial-direction and an outer region placed on the outer side in the tire radial-direction with respect to a position of an outer end of a belt play in a tire width-direction, the belt play placed on the innermost side in the tire radial-direction. A depth of the opening in the inner region is different from a depth of the opening in the outer region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of Japanese application no. 2016-174671, filed on Sep. 7, 2016, and Japanese application no. 2016-174701, filed on Sep. 7, 2016, which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a pneumatic tire having a plurality of projecting portions which project in a tire width-direction.

Description of the Related Art

There are conventionally known pneumatic tires each having a plurality of projecting portions which project in a tire width-direction (e.g., JP-A-2010-264962). According to a structure of this pneumatic tire, traction performance on a mud area or a rocky area is enhanced due to resistance caused when the projecting portions shear dirt and due to friction between the projecting portions and rock, and resistance to external damage is enhanced due to increase in rubber thickness.

By the way, weight balance of the tire is prone to become uneven due to existence of the projecting portions. Accordingly, when the tire is produced (vulcanized), rubber does not smoothly flow, the tire may be chipped (bare may be generated) with respect to a desired tire shape, or uniformity may be lowered and this may cause vibration or noise of a vehicle.

SUMMARY OF INVENTION

It is an object of the present invention to provide a pneumatic tire capable of suppressing unevenness of weight balance.

There is provided a pneumatic tire, which includes:

a sidewall portion extending in a tire radial-direction; and

a tread portion having a tread surface on an outer side in the tire radial-direction and connected to an outer end of the sidewall portion in the tire radial-direction, wherein

the tread portion includes a tread rubber placed on the outer side in the tire radial-direction, and at least one belt ply placed on an inner side of the tread rubber in the tire radial-direction,

the tread rubber includes a plurality of grooves extending to an outer end in a tire width-direction, and a plurality of blocks arranged in a tire circumferential-direction by being defined by the plurality of grooves,

the sidewall portion includes a plurality of projecting portions projecting in the tire width-direction,

the projecting portions are placed such that at least portions of the projecting portions are superposed on one of the plurality of blocks in the tire radial-direction as viewed from the tire width-direction,

at least one of the plurality of projecting portions includes at least one opening,

at least one of the projecting portions is divided into an inner region placed on the inner side in the tire radial-direction and an outer region placed on the outer side in the tire radial-direction with respect to a position of an outer end of the belt play in the tire width-direction, wherein the belt play placed on the innermost side in the tire radial-direction, and

a depth of the opening in the inner region is different from a depth of the opening in the outer region.

Also, the pneumatic tire may have a configuration in which:

the depth of the opening in the inner region is greater than that of the opening in the outer region.

Also, the pneumatic tire may have a configuration in which:

in a ratio of the total sums of the opening areas of the opening with respect to an actual area of the projecting portion, the ratio of the inner region is greater than the ratio of the outer region.

Also, the pneumatic tire may have a configuration in which:

a projecting amount of the projecting portion in the inner region is greater than a projecting amount of the projecting portion in the outer region.

Also, the pneumatic tire may have a configuration in which:

at least one of the projecting portions includes a convex portion accommodated in the opening placed in the inner region, and

the convex portion extends along the tire circumferential-direction.

Also, the pneumatic tire may have a configuration in which:

a projecting amount of the convex portion is equal to more than ½ of the depth of the opening.

Also, the pneumatic tire may have a configuration in which:

the depth of the opening in the outer region is greater than that of the opening in the inner region.

Also, the pneumatic tire may have a configuration in which:

in a ratio of the total sums of the opening areas of the opening with respect to an actual area of the projecting portion, the ratio of the outer region is greater than the ratio of the inner region.

Also, the pneumatic tire may have a configuration in which:

a projecting amount of the projecting portion in the outer region is greater than a projecting amount of the projecting portion in the inner region.

Also, the pneumatic tire may have a configuration in which:

at least one of the projecting portions includes a convex portion accommodated in the opening placed in the outer region, and

the convex portion extends along the tire radial-direction.

Also, the pneumatic tire may have a configuration in which:

a projecting amount of the convex portion is equal to more than ½ of the depth of the opening.

Also, there is provided a pneumatic tire, which includes:

a sidewall portion extending in a tire radial-direction; and

a tread portion having a tread surface on an outer side in the tire radial-direction and connected to an outer end of the sidewall portion in the tire radial-direction, wherein

the tread portion includes a tread rubber placed on the outer side in the tire radial-direction, and at least one belt ply placed on an inner side of the tread rubber in the tire radial-direction,

the tread rubber includes a plurality of grooves extending to an outer end in a tire width-direction, and a plurality of blocks arranged in a tire circumferential-direction by being defined by the plurality of grooves,

the sidewall portion includes a plurality of projecting portions projecting in the tire width-direction,

the projecting portions are placed such that at least portions of the projecting portions are superposed on one of the plurality of blocks in the tire radial-direction as viewed from the tire width-direction,

at least one of the plurality of projecting portions includes at least one opening,

at least one of the projecting portions is divided into an inner region placed on the inner side in the tire radial-direction and an outer region placed on the outer side in the tire radial-direction with respect to a position of an outer end of the belt play in the tire width-direction, wherein the belt play placed on the innermost side in the tire radial-direction, and

a depth of the opening in the inner region is equal to or greater than a depth of the opening in the outer region.

Also, there is provided a pneumatic tire, which includes:

a sidewall portion extending in a tire radial-direction; and

a tread portion having a tread surface on an outer side in the tire radial-direction and connected to an outer end of the sidewall portion in the tire radial-direction, wherein

the tread portion includes a tread rubber placed on the outer side in the tire radial-direction, and at least one belt ply placed on an inner side of the tread rubber in the tire radial-direction,

the tread rubber includes a plurality of grooves extending to an outer end in a tire width-direction, and a plurality of blocks arranged in a tire circumferential-direction by being defined by the plurality of grooves,

the sidewall portion includes a plurality of projecting portions projecting in the tire width-direction,

the projecting portions are placed such that at least portions of the projecting portions are superposed on one of the plurality of blocks in the tire radial-direction as viewed from the tire width-direction,

at least one of the plurality of projecting portions includes at least one opening,

at least one of the projecting portions is divided into an inner region placed on the inner side in the tire radial-direction and an outer region placed on the outer side in the tire radial-direction with respect to a position of an outer end of the belt play in the tire width-direction, wherein the belt play placed on the innermost side in the tire radial-direction, and

a depth of the opening in the outer region is equal to or greater than a depth of the opening in the inner region.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A pneumatic tire of a first embodiment will be described below with reference toFIGS. 1 to 11. Size ratios in each of the drawings (includingFIGS. 12 to 21) do not always match with actual size ratios, and size ratios between the drawings do not always math with each other.

As shown inFIG. 1, the pneumatic tire (also called “tire” simply)1includes a pair of bead portions11having beads11a. The tire1includes sidewall portions12extending from the bead portions11radially outward in a tire radial-direction D2, and a tread portion13which is connected to outer ends of the pair of sidewall portions12in the tire-radial direction D2. The tread portion13is provided with a tread surface13awhich comes into contact with ground. The tread surface13ais located on the outer side of in a tire radial-direction D2. The tire1is mounted on a rim (not shown).

The tire1includes a carcass layer14extending between the pair of beads11aand11a, and an inner linear15located on an inner side of the carcass layer14and facing an inner space of the tire1into which air is charged. The carcass layer14and the inner linear15are placed along an inner periphery of the tire over the bead portions11, the sidewall portions12and the tread portion13.

InFIG. 1(also in the other drawings), a first direction D1is a tire width-direction D1which is parallel to the tire rotation axis, a second direction D2is the tire radial-direction D2which is a diameter direction of the tire1, and a third direction D3(seeFIGS. 2 and 3, for example) is a tire circumferential-direction D3which is a direction around a tire axial-direction. One direction D2aof the second direction D2is directed inner side of the tire radial-direction D2, and the other direction D2bis directed outer side of the tire radial-direction D2. A tire equator surface S1is a surface intersecting with the tire rotation axis at right angle, and is located on a center of the tire width-direction D1, and a tire meridional surface is a surface including a surface including the tire rotation axis, and intersecting with the tire equator surface S1.

Each of the beads11aincludes an annularly formed bead core11b, and a bead filler11cplaced on an outer side of the bead core11bin the tire radial-direction D2. For example, the bead core11bis formed by laminating rubber-coated bead wires (metal wires, for example), and the bead filler11cis formed by forming hard rubber outward of the tire radial-direction D2in a tapered manner.

Each of the bead portions11includes a rim strip rubber11dplaced on an outer side in the tire width-direction D1than the carcass layer14to configure an outer surface which comes into contact with the rim. Each of the sidewall portions12includes a sidewall rubber12awhich is placed on an outer side in the tire width-direction D1than the carcass layer14to configure an outer surface.

The tread portion13includes a tread rubber13b. An outer surface of the tread rubber13bconfigures the tread surface13a. The tread portion13also includes a belt portion13cplaced between the tread rubber13band the carcass layer14. The belt portion13cincludes a plurality of (four inFIG. 1) belt plies13d. For example, each of the belt plies13dincludes a plurality of belt cords (organic fiber or metal, for example) which are arranged in parallel, and topping rubbers for coating the belt cords.

The carcass layer14is composed of at least one (two inFIG. 1) carcass plies14a. Each of the carcass plies14ais folded back around the bead11ato surround the bead11a. Each of the carcass plies14aincludes a plurality of ply cords (organic fiber or metal, for example) which are arranged in a direction intersecting with the tire circumferential-direction D3substantially at right angles, and topping rubbers for coating the ply cords.

To maintain the air pressure, the inner linear15has an excellent function to prevent gas from passing through the inner linear15. In the sidewall portion12, the inner linear15is in intimate contact with an inner periphery of the carcass layer14, and no other material is interposed between the inner linear15and the carcass layer14.

For example, in a distance between the carcass ply14awhich is placed on the innermost side and a tire inner peripheral surface (inner peripheral surface of inner linear15), the distance of the sidewall portion12is 90% to 180% of the distance of the tread portion13. More specifically, the distance of the sidewall portion12is 120% to 160% of the distance of the tread portion13.

An outer surface of the sidewall portion12has a position12bwhich becomes the same, in the tire radial-direction D2, as the tire maximum position (more specifically, maximum distance position of distance of carcass layer14between outer sides in tire width-direction D1). The position12bis called a tire maximum width position12b, hereinafter.

The outer surface of the sidewall portions12has a position12cwhich becomes the same, in the tire radial-direction D2, as an outer end11eof the bead filler11cin the tire radial-direction D2. The position12cis called a bead filler outer end position12c, hereinafter.

The outer surface of the sidewall portions12has a position12dwhich becomes the same, in the tire radial-direction D2, as an outer end13ein the tire width-direction D1in one of the plurality of belt plies13dwhich is placed on the innermost side in the tire radial-direction D2. This position12dis called a belt end position12d, hereinafter.

As shown inFIGS. 2 to 4, the tread portion13includes a plurality of grooves2extending to the outer end of the tread portion13in the tire width-direction D1, and a plurality of blocks3which are defined by the plurality of grooves2, thereby being arranged in the tire circumferential-direction D3. Each of the sidewall portions12includes a plurality of projecting portions4projecting from a profile surface (reference surface) S2in the tire width-direction D1, and an annular protrusion portion5projecting from the profile surface S2in the tire width-direction D1, and extending along the tire circumferential-direction D3.

The projecting portions4are placed at least on the outer side in the tire radial-direction D2of the sidewall portions12. According to this, the projecting portions4can come into contact with mud and sand in a state where the tire1sinks due to a weight of the vehicle in a mud area and a sand area, or can come into contact with the uneven rocks in a rocky area. That is, the projecting portions4come into contact with the ground in bad roads such as a mud area, a sand area and a rocky area. The projecting portions4do not normally come into contact with the ground in a flat road.

The projecting portions4are located on an outer side in the tire radial-direction D2than a bead filler outer end position12c(seeFIG. 1) of the sidewall portion12. More specifically, the projecting portions4are placed on the outer side in the tire radial-direction D2than a tire maximum width position12b(seeFIG. 1) of the sidewall portion12.

The projecting portions4are placed such that at least portions of them are superposed at least one of the plurality of blocks3in the tire radial-direction D2as viewed from the tire width-direction D1. That is, the projecting portions4are superposed on only one of the blocks3in the tire radial-direction D2as viewed from the tire width-direction D1. For example, the projecting portion4is superposed on the block3in the tire radial-direction D2as viewed from the tire width-direction D1by 25% or more in the tire circumferential-direction D3(preferably 50% or more, more preferably 75% or more).

An outer end4aof the projecting portion4in the tire radial-direction D2is located on an inner side in the tire radial-direction D2than the tread surface13aof the block3. According to this, an uneven shape is formed by the tread surface13aof the block3and the outer end4aof the projecting portion4in the tire radial-direction D2.

Since the uneven shape exists, components of the surfaces and the edges are formed. The uneven shape is formed on the portion where the tire comes into contact with the ground such as mud, sand and rock, an area which comes into contact with the ground such as mud, sand and rock is increased, or the surface and the edge formed by the uneven shape easily come into contact with the ground such as mud, sand and rock at various positions. If the uneven shape is formed on the portion where the tire comes into contact with the ground such as mud, sand and rock, the traction performance is enhanced.

Each of the projecting portions4includes openings6and7. According to this, a weight of the tire increases due to the existence of the projecting portion4, and the openings6and7restrain the weight from increasing. This configuration restrains the weight balance from becoming non-uniform which may be caused by the existence of the projecting portion4. Due to the existence of the openings6and7, the components of the surfaces and edges are increased and thus, the traction performance is enhanced. The first and second openings6and7are formed into rectangular shape as viewed from the tire width-direction D1.

The openings6and7are separated from both end edges of the projecting portion4in the tire radial-direction D2. Further, the openings6and7are separated from the both end edges of the projecting portion4in the tire circumferential-direction D3. According to this, since the rigidity of the projecting portion4around the openings6and7can be enhanced, traction performance can be maintained by the projecting portion4. For example, a width size between the opening edges of the openings6and7and the end edge of the projecting portion4is 1.5 mm or more (preferably, 2.0 mm or more).

The openings6and7are placed such that they include a center of the projecting portion4in the tire circumferential-direction D3. More specifically, central positions of the openings6and7in the tire circumferential-direction D3match with the central position of the projecting portion4in the tire circumferential-direction D3. The openings6and7are line-symmetric with respect to center of the projecting portion4in the tire circumferential-direction D3. According to this, this configuration restrains the weight balance from becoming non-uniform in the tire circumferential-direction D3, and thus it is possible to restrain the uniformity when the tire is mounted on the vehicle from becoming deteriorated.

Each of the projecting portions4is divided into an inner region4bwhich is placed on the inner side in the tire radial-direction D2and an outer region4cwhich is placed on the outer side in the tire radial-direction D2. In this embodiment, since the belt end position12dis located at the same position as the annular protrusion portion5, the inner region4bis located on the inner side in the tire radial-direction D2than the annular protrusion portion5, and the outer region4cis located on the outer side in the tire radial-direction D2than the annular protrusion portion5.

Each of the projecting portions4includes the two openings6and7. More specifically, the projecting portion4includes the first opening6placed on the inner side in the tire radial-direction D2and the second opening7placed on the outer side in the tire radial-direction D2. The first opening6is placed on the inner side in the tire radial-direction D2than the annular protrusion portion5, and the second opening7is placed on the outer side in the tire radial-direction D2than the annular protrusion portion5. That is, the first opening6is placed in the inner region4b, and the second opening7is placed in the outer region4c.

As shown inFIG. 5, when a tire1mounted on a vehicle comes into contact with ground20, the tire1becomes deformed by weight of the vehicle and the like. InFIG. 5, dashed-two dotted lines show shapes before the tire is deformed, and solid lines show shapes after deformation. At this time, the tire1generally becomes deformed differently from the belt end position12das a reference.

More specifically, the inner region4bbecomes deformed such that it is oriented to the sideway as shown by the solid lines, and the outer region4cbecomes deformed such that it is oriented to the ground20as shown by a broken arrow. Therefore, the first opening6of the inner region4bacts advantageously for the traction when the tire1comes into contact with the ground such as rock standing from the surface of the ground20.

Referring back toFIG. 4, a depth (maximum depth) of the first opening6in the inner region4bis greater than a depth (maximum depth) of the second opening7in the outer region4c. According to this, since a surface of the first opening6becomes large, friction between the first opening6and a rock becomes great. Therefore, it is possible to enhance the traction performance in the rocky area.

Further, a projecting amount (maximum projecting amount) of the projecting portion4in the inner region4bbecomes greater than a projecting amount (maximum projecting amount) of the projecting portion4in the outer region4c. According to this, although the depth of the first opening6is deep, a rubber volume of the inner region4bis secured. Therefore, it is possible to restrain the resistance to external damage of the inner region4bfrom being deteriorated.

As shown inFIGS. 6 to 9, a ratio (A1/A3) of a total sum A1of an opening area (meshed area inFIG. 6) of the first opening6to an actual area A3(meshed area inFIG. 8) of the projecting portion4in the inner region4bis greater than a ratio (A2/A4) of a total sum A2of an opening area (meshed area inFIG. 7) of the second opening7to an actual area A4(meshed area inFIG. 9) of the projecting portion4in the outer region4c. According to this, since a rock easily comes into contact with a surface and an edge of the first opening6, friction is more easily generated between the first opening6and the rock. Therefore, it is possible to enhance the traction performance in the rocky area.

As described above, the pneumatic tire1of the embodiment include a sidewall portion12extending in a tire radial-direction D2, and a tread portion13having a tread surface13aon an outer side in the tire radial-direction D2and connected to an outer end of the sidewall portion12in the tire radial-direction D2. The tread portion13includes a tread rubber13bplaced on the outer side in the tire radial-direction D2, and at least one belt ply13dplaced on an inner side of the tread rubber13bin the tire radial-direction D2. The tread rubber13bincludes a plurality of grooves2extending to an outer end in a tire width-direction D1, and a plurality of blocks3arranged in a tire circumferential-direction D3by being defined by the plurality of grooves2. The sidewall portion12includes a plurality of projecting portions4projecting in the tire width-direction D1. The projecting portions4are placed such that at least portions of the projecting portions4are superposed on one of the plurality of blocks3in the tire radial-direction D2as viewed from the tire width-direction D1. At least one of the plurality of projecting portions4includes at least one openings6and7. At least one of the projecting4portions is divided into an inner region4bplaced on the inner side in the tire radial-direction D2and an outer region4cplaced on the outer side in the tire radial-direction D2with respect to a position of an outer end13eof the belt play13din the tire width-direction D1, wherein the belt play13dplaced on the innermost side in the tire radial-direction D2. A depth of the opening6in the inner region4bis greater than a depth of the opening7in the outer region4c.

According to the above-described configuration, the projecting portion4is placed such that at least portion of the projecting portion4is superposed on at least one of the plurality of blocks3in the tire radial-direction D2as viewed from the tire width-direction D1. Therefore, traction performance is exhibited by a positional relation (e.g., uneven shape) between the block3and the projecting portion4in the tire width-direction D1.

Due to the existence of the projecting portions4, a rubber weight of this portion is increased. Hence, at least one of the plurality of projecting portions4includes the openings6and7. According to this, it is possible to restrain the unevenness of the weight balance which may be caused by the existence of the projecting portions4. Further, the traction performance is exhibited by the surfaces and the edges of the openings6and7.

In the sidewall portions12, generally, the inner region4blocated on the inner side in the tire radial-direction D2becomes deformed such that the inner region4bis oriented to sideway from the position, as a reference, of the outer end13eof the tire width-direction D1of the belt ply13dplaced on the innermost side in the tire radial-direction D2. Hence, a depth of the opening6in the inner region4bis greater than the opening7in the outer region4c.

According to this, since a surface of the opening6in the inner region4bbecomes large, a friction force between the opening6in the inner region4band rock becomes great. Therefore, it is possible to efficiently enhance traction performance in a rock area.

In the pneumatic tire1of the embodiment, in a ratio of the total sums A1and A2of the opening areas of the openings6and7with respect to an actual area A3and A4of the projecting portion4, the ratio (A1/A3) of the inner region4bis greater than the ratio (A2/A4) of the outer region4c.

According to the above-described configuration, in the ratio of the total sums A1and A2of the opening areas of the openings6and7to the actual areas A3and A4of the projecting portion4, the ratio (A1/A3) of the inner region4bis greater than the ratio (A2/A4) of the outer region4c. Therefore, rock easily comes into contact with the surface and the edge of the opening6in the inner region4b. According to this, friction is more easily generated between the opening6of the inner region4band the rock. Hence, it is possible to further efficiently enhance the traction performance in the rocky area.

In the pneumatic tire1of the embodiment, a projecting amount of the projecting portion4in the inner region4bis greater than a projecting amount of the projecting portion4in the outer region4c.

According to the above-described configuration, the projecting amount of the projecting portion4in the inner region4bbecomes greater than a projecting amount of the projecting portion4in the outer region4c. Therefore, it is possible to restrain the rubber volume of the inner region4bfrom becoming small, for example. According to this, it is possible to restrain the resistance to external damage of the inner region4bfrom being deteriorated, for example.

The pneumatic tire is not limited to the configuration of the first embodiment, and the pneumatic tire is not limited to the effect of the first embodiment. For example, the pneumatic tire of the first embodiment may be changed in the following manners.

As shown inFIGS. 10 and 11, in the pneumatic tire1, at least one of the projecting portions4may include a convex portion8which is accommodated in the opening6placed in the inner region4b, and the convex portion8may extend along the tire circumferential-direction D3.

According to the above-described configuration, since at least one of the plurality of projecting portions4includes the convex portion8accommodated in the opening6, traction performance is exhibited by a surface and an edge of the convex portion8. Since the convex portion8extends along the tire circumferential-direction D3, when the convex portion8runs on rock, a friction force between the surface of the convex portion8and the rock becomes great. According to this, it is possible to enhance the traction performance in a rocky area.

The convex portion8may be formed such that its tip end becomes a flat surface shape. For example, a cross section of the convex portion8may be formed into a trapezoidal shape. According to the above-described configuration, since the tip end of the convex portion8is the flat surface shape, rigidity of the convex portion8becomes great. According to this, since the traction performance caused by the surface and the edge of the convex portion8can effectively be exhibited, it is possible to effectively enhance the traction performance. Further, since it is possible to restrain the convex portion8from being chipped, it is possible to restrain the resistance to external damage from being lowered.

A projecting amount of the convex portion8is smaller than a depth of the opening6. The projecting amount of the convex portion8is ½ or more of the depth of the opening6. The convex portion8includes a top surface8aplaced on its tip end, and a side surface8bwhich forms a predetermined intersection angle θ1between itself and the top surface8a. It is preferable that the intersection angle θ1is 105° or more and 130° or less. According to this, it is possible to secure the rigidity of the convex portion8.

The convex portion8may be accommodated not only in the opening6placed in the inner region4bbut also in the opening7placed in the outer region4c. It is possible to employ not only the configuration that the convex portion8extends along the tire circumferential-direction D3but also a configuration that the convex portion8extends along the tire radial-direction D2.

In the pneumatic tire1of the first embodiment, in the ratio of the total sums A1and A2of the opening areas of the openings6and7to the actual areas A3and A4of the projecting portion4, the ratio (A1/A3) of the inner region4bis greater than the ratio (A2/A4) of the outer region4c. However, the pneumatic tire is not limited to this configuration. For example, the ratio (A1/A3) of the inner region4bmay be smaller than the ratio (A2/A4) of the outer region4c. Alternatively, the ratio (A1/A3) of the inner region4bmay be the same as the ratio (A2/A4) of the outer region4c.

In the pneumatic tire1of the first embodiment, the projecting amount of the projecting portion4in the inner region4bis greater than the projecting amount of the projecting portion4in the outer region4c. However, the pneumatic tire is not limited to this configuration. For example, the projecting amount of the projecting portion4in the inner region4bmay be smaller than the projecting amount of the projecting portion4in the outer region4c. Alternatively, the projecting amount of the projecting portion4in the inner region4bmay be the same as the projecting amount of the projecting portion4in the outer region4c.

Second Embodiment

Next, a second embodiment in the pneumatic tire will be described with reference toFIGS. 12 to 21. InFIGS. 12 to 21, elements to which the same reference signs as those ofFIGS. 1 to 11are denoted have substantially the same configurations or functions (effects) as the first embodiment, and description thereof will not be repeated.

As shown inFIGS. 12 to 14, a tread portion13includes a plurality of grooves2and a plurality of blocks3, each of sidewall portions12includes a plurality of projecting portions4and an annular protrusion portion5, and each of the projecting portions4includes openings6and7. Configuration of the projecting portions4and the openings6and7of this embodiment are different from those of the projecting portions4and the openings6and7of the first embodiment.

As shown inFIG. 15, when the tire1mounted on the vehicle comes into contact with the ground20, the tire1becomes deformed by the weight of the vehicle and the like. InFIG. 15, dashed-two dotted lines show shapes before the tire is deformed, and solid lines show shapes after deformation. At this time, the tire1generally becomes deformed differently from the belt end position12das a reference.

More specifically, the inner region4bbecomes deformed such that it is oriented to the sideway as shown by the solid lines, and the outer region4cbecomes deformed such that it is oriented to the ground20as shown by a broken arrow. Therefore, the second opening7in the outer region4cacts advantageously for the traction when the tire1comes into contact with the ground such as mud accumulated on the surface of the ground20.

Referring back toFIG. 14, a depth (maximum depth) of the second opening7in the outer region4cis greater than a depth (maximum depth) of the first opening6in the inner region4b. According to this, since a surface of the second opening7becomes large, resistance when the second opening7shears mud becomes great. Therefore, it is possible to enhance the traction performance in the mud area.

Further, a projecting amount (maximum projecting amount) of the projecting portion4in the outer region4cbecomes greater than a projecting amount (maximum projecting amount) of the projecting portion4in the inner region4b. According to this, although the opening area of the second opening7is great and the depth of the second opening7is deep, a rubber volume of the outer region4cis secured. Therefore, it is possible to restrain the resistance to external damage of the outer region4cfrom being deteriorated.

As shown inFIGS. 16 to 19, a ratio (A2/A4) of the total sum A2of the opening area (meshed region inFIG. 17) of the second opening7to an actual area A4(meshed region inFIG. 19) of the projecting portion4in the outer region4cis greater than a ratio (A1/A3) of the total sum A1of an opening area (meshed region inFIG. 16) of the first opening6to an actual area A3(meshed region inFIG. 18) of the projecting portion4in the inner region4b. According to this, since mud easily enters the second opening7, mud in the second opening7is easily sheared. Therefore, if is possible to enhance the traction performance in the mud area.

As described above, the pneumatic tire1of the embodiment include a sidewall portion12extending in a tire radial-direction D2, and a tread portion13having a tread surface13aon an outer side in the tire radial-direction D2and connected to an outer end of the sidewall portion12in the tire radial-direction D2. The tread portion13includes a tread rubber13bplaced on the outer side in the tire radial-direction D2, and at least one belt ply13dplaced on an inner side of the tread rubber13bin the tire radial-direction D2. The tread rubber13bincludes a plurality of grooves2extending to an outer end in a tire width-direction D1, and a plurality of blocks3arranged in a tire circumferential-direction D3by being defined by the plurality of grooves2. The sidewall portion12includes a plurality of projecting portions4projecting in the tire width-direction D1. The projecting portions4are placed such that at least portions of the projecting portions4are superposed on one of the plurality of blocks3in the tire radial-direction D2as viewed from the tire width-direction D1. At least one of the plurality of projecting portions4includes at least one openings6and7. At least one of the projecting4portions is divided into an inner region4bplaced on the inner side in the tire radial-direction D2and an outer region4cplaced on the outer side in the tire radial-direction D2with respect to a position of an outer end13eof the belt play13din the tire width-direction D1, wherein the belt play13dplaced on the innermost side in the tire radial-direction D2. A depth of the opening7in the outer region4cis greater than a depth of the opening6in the inner region4b.

According to the above-described configuration, the projecting portion4is placed such that at least portion of the projecting portion4is superposed on at least one of the plurality of blocks3in the tire radial-direction D2as viewed from the tire width-direction D1. Therefore, traction performance is exhibited by a positional relation (e.g., uneven shape) between the block3and the projecting portion4in the tire width-direction D1.

Due to the existence of the projecting portions4, a rubber weight of this portion is increased. Hence, at least one of the plurality of projecting portions4includes the openings6and7. According to this, it is possible to restrain the unevenness of the weight balance which may be caused by the existence of the projecting portions4. Further, the traction performance is exhibited by the surfaces and the edges of the openings6and7.

In the sidewall portions12, generally, the outer region4clocated on the outer side in the tire radial-direction D2becomes deformed such that the outer region4cis oriented to the ground20from the position, as a reference, of the outer end13eof the tire width-direction D1of the belt ply13dplaced on the innermost side in the tire radial-direction D2. Hence, the depth of the opening7in the outer region4cis greater than the opening6in the inner region4b.

According to this, since the surface of the opening7of the outer region4cbecomes large, resistance when the opening7of the outer region4cshears mud becomes large. Therefore, it is possible to more effectively enhance the traction performance in the mud area.

In the pneumatic tire1of the embodiment, in a ratio of the total sums A1and A2of the opening areas of the openings6and7with respect to an actual areas A3and A4of the projecting portion4, the ratio (A2/A4) of the outer region4cis greater than the ratio (A1/A3) of the inner region4b.

According to the above-described configuration, in the ratio of the total sums A1and A2of the opening areas of the openings6and7to the actual areas A3and A4of the projecting portion4, the ratio (A2/A4) of the outer region4cis greater than the ratio (A1/A3) of the inner region4b. Therefore, mud easily enters the opening7of the outer region4c. According to this, since shear of mud in the opening7in the outer region4cis more easily generated, it is possible to further efficiently enhance the traction performance in the mud area.

In the pneumatic tire1of the embodiment, a projecting amount of the projecting portion4in the outer region4cis greater than a projecting amount of the projecting portion4in the inner region4b.

According to the above-described configuration, since the projecting amount of the projecting portion4in the outer region4cbecomes greater than the projecting amount of the projecting portion4in the inner region4b, it is possible to restrain the rubber volume of the outer region4cfrom becoming small. According to this, it is possible to restrain the resistance to external damage of the outer region4cfrom being deteriorated.

The pneumatic tire is not limited to the configuration of the second embodiment, and the pneumatic tire is not limited to the effect of the second embodiment. For example, the pneumatic tire of the second embodiment may be changed in the following manners.

As shown inFIGS. 20 and 21, in the pneumatic tire1, at least one of the projecting portions4may include a convex portion8which is accommodated in the opening7placed in the outer region4c, and the convex portion8may extend along the tire radial-direction D2.

According to the above-described configuration, since at least one of the plurality of projecting portions4includes the convex portion8accommodated in the opening7, traction performance is exhibited by a surface and an edge of the convex portion8. Since the convex portions8extend along the tire radial-direction D2, resistance when the surface of the convex portion8shears becomes great when the convex portions8are soaked in mud. According to this, traction performance can be enhanced in a mud area.

The convex portion8may be formed such that its tip end becomes a flat surface shape. For example, a cross section of the convex portion8may be formed into a trapezoidal shape. According to the above-described configuration, since the tip end of the convex portion8is the flat surface shape, rigidity of the convex portion8becomes great. According to this, since the traction performance caused by the surface and the edge of the convex portion8can effectively be exhibited, it is possible to effectively enhance the traction performance. Further, since it is possible to restrain the convex portion8from being chipped, it is possible to restrain the resistance to external damage from being lowered.

A projecting amount of the convex portion8is smaller than a depth of the opening7. The projecting amount of the convex portion8is ½ or more of the depth of the opening7. The convex portion8includes a top surface8aplaced on its tip end, and a side surface8bwhich forms a predetermined intersection angle θ1between itself and the top surface8a. It is preferable that the intersection angle θ1is 105° or more and 130° or less. According to this, it is possible to secure the rigidity of the convex portion8.

The convex portion8may be accommodated not only in the opening7placed in the outer region4cbut also in the opening6placed in the inner region4b. It is possible to employ not only the configuration that the convex portion8extends along the tire radial-direction D2but also a configuration that the convex portion8extends along the tire circumferential-direction D3.

In the pneumatic tire1of the second embodiment, in the ratio of the total sums A1and A2of the openings6and7to the actual areas A3and A4of the projecting portion4, the ratio (A2/A4) of the outer region4cis greater than the ratio (A1/A3) of the inner region4b. However, the pneumatic tire is not limited to this configuration. For example, the ratio (A2/A4) of the outer region4cmay be smaller than the ratio (A1/A3) of the inner region4b. Alternatively, the ratio (A2/A4) of the outer region4cmay be the same as the ratio (A1/A3) of the inner region4b.

In the pneumatic tire1of the second embodiment, the projecting amount of the projecting portion4in the outer region4cis greater than the projecting amount of the projecting portion4in the inner region4b. However, the pneumatic tire is not limited to this configuration. For example, the projecting amount of the projecting portion4in the outer region4cmay be smaller than the projecting amount of the projecting portion4in the inner region4b. Alternatively, the projecting amount of the projecting portion4in the outer region4cmay be the same as the projecting amount of the projecting portion4in the inner region4b.

Note that, the pneumatic tire is not limited to the configurations of the above-described embodiment, and is not limited to the above-described working effects. The pneumatic tire can of course be variously modified within a scope not departing from the subject matters of the present invention. For example, the configurations and methods of the above-described plurality of embodiments may arbitrarily be employed and combined (configuration or method of one of embodiments may be applied to configuration or method of other embodiment), and it is possible to arbitrarily select one or more of configurations and methods of the later-described various modifications, and such configurations and methods may be employed for the configurations or the methods of the above-described embodiments.

In the pneumatic tire1of the embodiments, two openings6and7are provided in one projecting portion4. However, the pneumatic tire is not limited to this configuration. For example, one or three or more openings may be provided in one projecting portion4.

In the pneumatic tire1of the embodiments, the openings6and7are formed into rectangular shapes as viewed from the tire width-direction D1. However, the pneumatic tire is not limited to this configuration. For example, the openings may be formed into a circular (perfect circular, elliptic) shape as viewed from the tire width-direction D1. Further, for example, the openings may be formed into a triangular shape or a polygonal shape having five angle portions or more as viewed from the tire width-direction D1.

In the pneumatic tire1of the embodiments, the openings6and7are provided in all of the projecting portions4. However, the pneumatic tire is not limited to this configuration. For example, it is only necessary that the openings6and7are provided at least in one of the plurality of projecting portions4. It is preferable that the openings6and7are provided at least in ¼ of the plurality of projecting portions4, it is more preferable that the openings6and7are provided at least in ⅓, and it is more preferable that the openings6and7are provided at least in ½.

In the pneumatic tire1of the embodiments, all of the projecting portions4have the same shapes, and all of the openings6and7have the same shape. However, the pneumatic tire is not limited to this configuration. The projecting portions4may have different shapes, and they may be placed in series in the tire circumferential-direction D3. Further, the openings6and7may have a plurality of different shapes, and may be placed in the respective projecting portions4in series in the tire circumferential-direction D3.

In the pneumatic tire1of the embodiments, the openings6and7are respectively separated from both end edges of the projecting portion4in the tire radial-direction D2. However, the pneumatic tire is not limited to this configuration. The openings6and7may be separated only from one of the end edges of the projecting portion4in the tire radial-direction D2.

In the pneumatic tire1of the embodiments, the openings6and7are respectively separated from both end edges of the projecting portion4in the tire circumferential-direction D3. However, the pneumatic tire is not limited to this configuration. The openings6and7may be separated only from one of the end edges of the projecting portion4in the tire circumferential-direction D3.

In the pneumatic tire1of the embodiments, the projecting portions4are provided on both of the pair of sidewall portions12. However, the pneumatic tire is not limited to this configuration. For example, the projecting portions4may be provided on one of the pair of sidewall portions12. For example, the projecting portions4may be provided on at least one of the pair of sidewall portions12which is placed on the outer side when the tire is mounted on the vehicle.

The pneumatic tire1may employ such as configuration that the projecting portions4are provided on both of the pair of sidewall portions12but the openings6and7are provided on one of or both of the sidewall portions12. For example, the openings6and7may be provided on one of the pair of sidewall portions12which is placed on the outer side when the tire is mounted on the vehicle.