Patent Description:
Conventionally, in an ultra-high performance tire mounted on a vehicle capable of traveling at an ultra-high speed exceeding <NUM>/h, it is important to ensure high-speed durability and steering stability. There is known an ultra-high performance tire that reduces tire noise (specifically, road noise) while securing such high-speed durability and steering stability (Patent Literature <NUM>).

The ultra-high performance tire is provided with a circumferential belt using a steel cord. Thus, the suppression of creep deformation and the improvement of rigidity in the tire circumferential direction are realized. In particular, by improving the rigidity in the tire circumferential direction, high frequency road noise during high-speed traveling can be suppressed.

In recent years, there has been an increasing demand for environmental performance, such as further reduction of tire noise, even for the ultra-high performance tires described above. In particular, the value of the tire noise (also referred to as pass-by noise (PBN)) produced when the power source (engine) of the vehicle is stopped and the vehicle is coasting at the specified speed is uniformly specified to be not more than <NUM> dB (for normal road) for tires having a tire width of more than <NUM> (ECE R <NUM>-<NUM>).

On the other hand, the performance of the vehicle is remarkably improved, and it is required to ensure rigidity for a large lateral force in order to cope with not only the maximum speed but also a high cornering speed.

Accordingly, the present invention has been made in view of such a situation, and an object of the present invention is to provide a tire capable of achieving both suppression of tire noise and high rigidity with respect to lateral force, while allowing the vehicle to travel at an ultra-high speed.

One aspect of the present invention is a tire according to claim <NUM>.

According to the tire described above, it is possible to achieve both the suppression of tire noise and the high rigidity with respect to lateral force while allowing the vehicle to travel at an ultra-high speed.

Embodiments will be described below with reference to the drawings. Note that the same functions and structures are denoted by the same or similar reference numerals, and the description thereof is omitted as appropriate.

<FIG> is a partial plan view of a tread of a pneumatic tire <NUM> according to the present embodiment. As shown in <FIG>, a pattern (tread pattern) is formed in a tread portion <NUM> of the pneumatic tire <NUM> in consideration of various performances required for the pneumatic tire <NUM>, specifically, high-speed durability, vehicle dynamics (cornering performance, steering stability, braking performance, etc.), drainage performance, wear resistance, rolling resistance (RR), quietness (tire noise), and the like.

The pneumatic tire <NUM> is a so-called ultra high performance (UHP) tire, and can be suitably used for a vehicle capable of traveling at such an ultra high speed that the traveling speed exceeds <NUM>/h.

Specifically, the pneumatic tire <NUM> may correspond to a speed symbol W (<NUM>/h), Y (<NUM>/h) or (Y) (greater than <NUM>/h) or a speed category ZR (greater than <NUM>/h). A speed symbol is a symbol representing the maximum speed at which a tire can run under prescribed conditions with the mass indicated by its load index.

The pneumatic tire <NUM> may not necessarily correspond to such a high maximum speed, and may correspond to, for example, the speed symbol V (<NUM>/h).

The size (rim diameter, tire width and aspect ratio) of the pneumatic tire <NUM> may be appropriately set according to the vehicle to be mounted, and is not particularly limited, but a rim diameter of <NUM> inches or more, a tire width of <NUM> or more, and an aspect ratio of <NUM>% or less are assumed. However, smaller rim diameters (for example, <NUM> inches), narrower tire widths (for example, <NUM>) and higher aspect ratio (for example, <NUM>%) may be used.

The tire width is also referred to as the section width. The section width is the total width of the tire excluding the patterns and characters on the sides of the tire, and does not include rim guards.

The pneumatic tire <NUM> can cope with running not only on a general road but also on a circuit (race course, race track). The pneumatic tire <NUM> also corresponds to wet weather, that is, wet road surface. The pneumatic tire <NUM> has sufficient rigidity for a large lateral force, especially to accommodate high cornering speed during circuit driving.

From such a viewpoint, in the pneumatic tire <NUM>, only a minimum number of groove elements (including sipes) for ensuring drainability are formed. Thus, the rigidity of the land portion is enhanced, and vehicle dynamics and wear resistance performance can be improved.

The pneumatic tire <NUM> clears the regulation value of the tire sole noise regulation international standard, specifically, ECE R <NUM>-<NUM>. ECE R <NUM>-<NUM> specifies that the tire noise (also referred to as pass-by noise (PBN)) produced when the vehicle power source (engine) is stopped and the vehicle coasts at the specified speed shall be uniformly <NUM> dB or less (for normal load) for tires with a tire width exceeding <NUM>. In the case of an extra load, <NUM> dB or less is specified.

Therefore, the pneumatic tire <NUM> may have a narrower tire width as described above, but is assumed to have a tire width exceeding <NUM> which makes it more difficult to clear the specified PBN.

The pneumatic tire <NUM> has a so-called asymmetric pattern, and a surface (tire side part) to be an outside (or inside) when the tire is mounted to the vehicle is designated. For the pneumatic tire <NUM>, it is not necessary to specify the rotational direction when the vehicle is mounted.

As shown in <FIG>, the pneumatic tire <NUM> has the tread portion <NUM>. The tread portion <NUM> is a part in contact with the road surface.

A plurality of linear circumferential grooves extending in the tire circumferential direction are formed in the tread portion <NUM>. Specifically, a circumferential groove <NUM>, a circumferential groove <NUM> and a circumferential groove <NUM> are formed in the tread portion <NUM>.

The circumferential groove <NUM> is formed most in outside when mounted to the vehicle. The circumferential groove <NUM> is formed outside than a tire equatorial line CL when mounted to the vehicle. In this embodiment, the circumferential groove <NUM> constitutes a first circumferential groove.

The circumferential groove <NUM> is formed between the circumferential groove <NUM> and the circumferential groove <NUM> in the tire width direction. The circumferential groove <NUM> is formed inside than the circumferential groove <NUM> when mounted to the vehicle. In this embodiment, the circumferential groove <NUM> forms a second circumferential groove.

The circumferential groove <NUM> is formed most in inside when mounted to the vehicle. That is, the circumferential groove <NUM> is formed in inside than the circumferential groove <NUM> when mounted to the vehicle. In this embodiment, the circumferential groove <NUM> constitutes a third circumferential groove.

The circumferential groove <NUM> and the circumferential groove <NUM> are formed inside than the tire equatorial line CL when mounted to the vehicle.

The tread portion <NUM> divided by the plurality of circumferential grooves has a plurality of land portions in contact with the road surface.

Specifically, the tread portion <NUM> includes an outside center land portion <NUM>, an inside center land portion <NUM>, an inside shoulder land portion <NUM>, and an outside shoulder land portion <NUM>.

The outside center land portion <NUM> is provided between the circumferential groove <NUM> and the circumferential groove <NUM> in the tire width direction. The outside center land portion <NUM> is a rib-like land portion continuous in the tire circumferential direction.

The inside center land portion <NUM> is provided between the circumferential groove <NUM> and the circumferential groove <NUM> in the tire width direction. The inside center land portion <NUM> is also a rib-like land portion continuous in the tire circumferential direction.

The inside shoulder land portion <NUM> is formed in a shoulder portion of inside when mounted to the vehicle. The inside shoulder land portion <NUM> is formed in inside than the circumferential groove <NUM> when mounted to the vehicle.

The outside shoulder land portion <NUM> is formed in a shoulder portion of outside when mounted to the vehicle. The outside shoulder land portion <NUM> is formed in outside than the circumferential groove <NUM> when mounted to the vehicle.

A plurality of width direction sipes <NUM> are formed in the outside center land portion <NUM>. The width direction sipes <NUM> are formed at a certain distance in the tire circumferential direction.

The width direction sipe <NUM> is a linear sipe extending in the tire width direction. One end of the width direction sipe <NUM> terminates within the outside center land portion <NUM>. The other end of the width direction sipe <NUM> communicates with the circumferential groove <NUM>.

The sipe is a narrow groove that closes within the ground plane of the tread portion <NUM>, and the opening width of the sipe at the time of non-grounding is not particularly limited, but is preferably <NUM> to <NUM>.

A plurality of width direction sipes <NUM> and width direction sipes <NUM> are formed in the inside center land portion <NUM>. A plurality of width direction sipes <NUM> and <NUM> are formed at a certain distance in the tire circumferential direction.

The width direction sipe <NUM> is formed near the circumferential groove <NUM>, and one end of the width direction sipe <NUM> terminates in the inside center land portion <NUM>. The width direction sipe <NUM> is formed near the circumferential groove <NUM>, and one end of the width direction sipe <NUM> terminates in the inside center land portion <NUM>.

The other end of the width direction sipe <NUM> communicates with the circumferential groove <NUM>, and the other end of the width direction sipe <NUM> communicates with the circumferential groove <NUM>.

In the present embodiment, the width direction sipe <NUM>, the width direction sipe <NUM>, and the width direction sipe <NUM> have similar shapes. The width direction sipe <NUM>, the width direction sipe <NUM> and the width direction sipe <NUM> are inclined to the tire width direction along the tire width direction. That is, the width direction sipe <NUM>, the width direction sipe <NUM>, and the width direction sipe <NUM> are not parallel to the tire width direction and are inclined to the tire width direction. The inclination angle of the width direction sipe <NUM>, the width direction sipe <NUM>, and the width direction sipe <NUM> with respect to the tire width direction is preferably <NUM> degrees or less, and is preferably <NUM> degrees or less in consideration of compatibility between rigidity of the land portion and PBN suppression.

In the present embodiment, the width direction sipes <NUM>, the width direction sipes <NUM>, and the width direction sipes <NUM> are inclined in the same direction, but it is not necessary that all the width direction sipes are inclined in the same direction. Further, the width direction sipe <NUM>, the width direction sipe <NUM> and the width direction sipe <NUM> are preferably offset from each other in the tire circumferential direction.

The inside shoulder land portion <NUM> has a slick portion <NUM> a. A plurality of shoulder grooves <NUM> terminating in the inside shoulder land portion <NUM> are formed in the inside shoulder land portion <NUM>. The shoulder grooves <NUM> are formed at a certain distance in the tire circumferential direction.

The slick portion <NUM> a is a portion having a slick-like surface of the inside shoulder land portion <NUM>. In this embodiment, the slick portion <NUM> a constitutes an inside slick portion.

The slick shape means that groove elements such as a width direction groove and a circumferential groove are not formed. It should be noted that a pinhole-like recess which can be used for determining the wear amount of the tread portion <NUM> or a protrusion such as a spew formed for the purpose of preventing air accumulation during tire vulcanization may be formed.

The slick portion <NUM> a may be defined as a portion in which the surface of the shoulder land portion <NUM> when normal load is loaded to the pneumatic tire <NUM> is slick in the ground contacting area (grounding region) of the inside shoulder land portion <NUM>.

When normal load is loaded on the pneumatic tire <NUM>, the ground contacting area CA contacts the road surface. As shown in <FIG>, no shoulder groove <NUM> is formed in the slick portion <NUM> a of the inside shoulder land portion <NUM>.

In Japan, normal internal pressure is the air pressure corresponding to the maximum load capacity of JATMA (Japan Automobile Tire Manufacturers Association) YearBook, and normal load is the maximum load capacity (maximum load) corresponding to the maximum load capacity of JATMA YearBook. In addition, ETRTO in Europe, TRA in the United States, and other tire standards in other countries are applicable.

Although the shoulder groove <NUM> is not formed in the ground contacting area CA, the area of the inside shoulder land portion <NUM> where the shoulder groove <NUM> is formed can also be grounded to the road surface during cornering or the like. The shoulder groove <NUM> may also serve as a treadwear indicator (slip sign) used to confirm the wear condition of the inside shoulder land portion <NUM>. The shoulder groove <NUM> may be formed for improving the grounding property of the inside shoulder land portion <NUM>.

The outside center land portion <NUM> has a slick portion <NUM> a. The slick portion <NUM> a is a portion having a slick-like surface of the outside center land portion <NUM>. The slick portion <NUM> a is formed in the region of outside when mounted to the vehicle in the outside center land portion <NUM>. That is, the slick portion <NUM> a may be defined as a portion where the surface of the outside center land portion <NUM> is slick in the region of outside when mounted to the vehicle in the outside center land portion <NUM>. In this embodiment, the slick portion <NUM> a constitutes a center slick portion.

The outside shoulder land portion <NUM> has a slick portion <NUM> a. The slick portion <NUM> a is a portion having has a slick-like surface of the outside shoulder land portion <NUM>. The slick portion <NUM> a is formed in the region of outside when mounted to the vehicle in the inside shoulder land portion <NUM>. That is, the slick portion <NUM> a may be defined as a portion where the surface of the outside shoulder land portion <NUM> is slick in the region of inside when mounted to the vehicle in the outside shoulder land portion <NUM>. In this embodiment, the slick portion <NUM> a constitutes an outside slick portion.

A plurality of lug grooves <NUM> are formed in the outside shoulder land portion <NUM>. A plurality of lug grooves <NUM> are formed at a certain distance in the tire circumferential direction.

The lug groove <NUM> is inclined to the tire width direction along the tire width direction. That is, the lug groove <NUM> is not parallel to the tire width direction but inclined to the tire width direction. The inclination angle of the lug groove <NUM> with respect to the tire width direction is preferably <NUM> degrees or less in the same manner as the width direction sipe <NUM>, the width direction sipe <NUM>, and the width direction sipe <NUM>, and is preferably <NUM> degrees or less in consideration of compatibility between rigidity of outside shoulder land portion <NUM> and PBN suppression.

In this embodiment, the sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM>, and the circumferential groove <NUM> is larger than the width of the outside center land portion <NUM> along the tire width direction.

The sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM> and the circumferential groove <NUM> is wider than the width of inside center land portion <NUM> along the tire width direction.

On the other hand, the sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM> and the circumferential groove <NUM> is narrower than the width of the slick portion <NUM> a, the slick portion <NUM> a and the slick portion <NUM> a along the tire width direction.

In the present embodiment, the width of the slick portion <NUM> a along the tire width direction is larger than the width of the outside center land portion <NUM> other than the slick portion <NUM> a along the tire width direction, that is, the width of the portion where the width direction sipe <NUM> is formed along the tire width direction.

In this embodiment, the width of the lug groove <NUM> in the ground contacting area CA along the tire width direction is larger than the width of the slick portion <NUM> a along the tire width direction.

Next, the cross-sectional shapes of the circumferential groove <NUM>, the circumferential groove <NUM>, and the circumferential groove <NUM> will be described. <FIG> is a schematic cross-sectional view of the pneumatic tire <NUM> along the tire width direction and the tire radial direction. In <FIG>, hatching of a cross section and a structure such as a carcass and a belt are omitted.

As shown in <FIG>, the outside shoulder land portion <NUM> has a groove wall portion <NUM> forming the circumferential groove <NUM>. In this embodiment, the groove wall portion <NUM> constitutes a first groove wall portion.

The outside center land portion <NUM> has a groove wall portion <NUM> forming the circumferential groove <NUM>. In this embodiment, the groove wall portion <NUM> constitutes a second groove wall portion.

The inside center land portion <NUM> has a groove wall portion <NUM> forming the circumferential groove <NUM>. In this embodiment, the groove wall portion <NUM> constitutes a third groove wall portion.

The groove wall portion <NUM>, the groove wall portion <NUM> and the groove wall portion <NUM> incline toward inside in the tire radial direction to approach inside when mounted to the vehicle. In this embodiment, the sectional shapes of the groove wall portion <NUM>, the groove wall portion <NUM>, and the groove wall portion <NUM> are linear. However, the entire groove wall portion may not necessarily be in a linear shape inclined toward inside the tire radial direction to approach inside when mounted to the vehicle.

In this embodiment, the groove depths of the circumferential groove <NUM>, the circumferential groove <NUM> and the circumferential groove <NUM> are the same.

The groove wall portion <NUM> is inclined more than the groove wall portion <NUM>. The groove wall portion <NUM> is inclined more than the groove wall portion <NUM>.

That is, the inclination angle of the groove wall portion <NUM> with respect to the tire radial direction is larger than the inclination angle of the groove wall portion <NUM> with respect to the tire radial direction, and the inclination angle of the groove wall portion <NUM> with respect to the tire radial direction is larger than the inclination angle of the groove wall portion <NUM> with respect to the tire radial direction. Therefore, the relation of the inclination angle is the groove wall portion <NUM> > the groove wall portion <NUM> > the groove wall portion <NUM>.

<FIG> is a plan view of the width direction sipe <NUM>. The width direction sipe <NUM> and the width direction sipe <NUM> have the same shape.

As shown in <FIG>, the width direction sipe <NUM> includes a width direction groove wall portion <NUM>, a width direction groove wall portion <NUM>, and a circumferential groove wall portion <NUM>.

The width direction groove wall portion <NUM> extends in the tire width direction. In this embodiment, the width direction groove wall portion <NUM> constitutes a first width direction groove wall portion.

The width direction groove wall portion <NUM> extends in the tire width direction like the width direction groove wall portion <NUM> and extends to the center side of the inside center land portion <NUM> from the width direction groove wall portion <NUM>. In this embodiment, the width direction groove wall portion <NUM> constitutes a second width direction groove wall portion. In the case of the width direction sipe <NUM>, the width direction groove wall portion <NUM> extends to the center side of the outside center land portion <NUM>.

The circumferential groove wall portion <NUM> is communicated to the width direction groove wall portion <NUM> and the width direction groove wall portion <NUM>. The circumferential groove wall portion <NUM> is linear.

Since the width direction groove wall portion <NUM> and the width direction groove wall portion <NUM> are different in length, the circumferential groove wall portion <NUM> is inclined with respect to the tire circumferential direction and also inclined with respect to the tire width direction. That is, one end of the width direction sipe <NUM> has a shape like a tip of a sword in a tread surface view.

An inclined portion <NUM> inclined toward inside in the tire radial direction from the tread surface (portion in contact with the road surface) side of the center land portion <NUM> is formed at a peripheral edge portion of the width direction sipe <NUM>.

The inclined portion <NUM> communicates to a sipe portion <NUM> of the width direction sipe <NUM>. The sipe part <NUM> is linear along the tire width direction, but may not necessarily be linear in tire radial direction, that is, the sipe depth direction. For example, the sipe portion <NUM> may have a shape that zigzags in the tire circumferential direction as it goes to inside in the tire radial direction. More specifically, the sipe portion <NUM> may be a so-called three-dimensional sipe having an M-shaped cross-sectional shape along the tire circumferential direction and the tire radial direction.

<FIG> is a plan view of the lug groove <NUM>. As shown in <FIG>, the lug groove <NUM> is formed by an inclined portion <NUM>, a groove portion <NUM>, an end portion <NUM>, and an end portion <NUM>. In this embodiment, the lug groove <NUM> has a slightly curved wedge-shape.

The inclined portion <NUM> is formed at the peripheral edge portion of the lug groove <NUM>. The inclined portion <NUM> is inclined toward inside in the tire radial direction from the tread surface side of the outside shoulder land portion <NUM>. The inclined portion <NUM> communicates to the groove portion <NUM>.

The groove portion <NUM> is a void having a certain depth in the tire radial direction. The depth of the groove portion <NUM> is not particularly limited, but is set to an appropriate value in consideration of drainability, grounding property (rigidity) of the outside shoulder land portion <NUM>, and PBN suppression.

The end portion <NUM> is an end portion of the lug groove <NUM> located in outside when mounted to the vehicle. The end portion <NUM> is an end portion of the lug groove <NUM> located in inside when mounted to the vehicle. The end portion <NUM> and the end portion <NUM> are offset in the tire circumferential direction, that is, their positions in the tire circumferential direction are different.

According to the above-described embodiment, the following effects can be obtained. More specifically, three circumferential grooves (circumferential groove <NUM>, circumferential groove <NUM>, and circumferential groove <NUM>) are formed in the tread portion <NUM> of the pneumatic tire <NUM>, and the outside center land portion <NUM>, the inside center land portion <NUM>, and the inside shoulder land portion <NUM> which are divided by the circumferential grooves are provided.

The plurality of width direction sipes (width direction sipe <NUM>, width direction sipe <NUM>, and width direction sipe <NUM>) are formed in the outside center land portion <NUM> and the inside center land portion <NUM>.

Firstly, the three circumferential grooves ensure the drainability necessary for travelling a vehicle mounted with an ultra-high performance tire such as the pneumatic tire <NUM>. Further, since the circumferential groove <NUM> and the circumferential groove <NUM> are formed in inside when mounted to the vehicle than the tire equatorial line CL, and the width direction sipe <NUM>, the width direction sipe <NUM> and the width direction sipe <NUM> are formed in inside when mounted to the vehicle than the tire equatorial line CL, the drainability of inside of the tread portion <NUM> on the basis of the tire equatorial line CL when mounted to the vehicle can be enhanced.

In addition, the inside shoulder land portion <NUM> has the slick portion <NUM> a n which the surface of the shoulder land portion <NUM> when normal load is loaded to the pneumatic tire <NUM> is slick in the ground contacting area of the inside shoulder land portion <NUM>.

Therefore, the slick portion <NUM> a can be located in the ground contacting area CA of the inside of the tread portion <NUM> on the basis of the tire equatorial line CL when mounted to the vehicle. Since the slick portion <NUM> a does not have a groove element, the rigidity of the inside shoulder land portion <NUM>, in particular, the rigidity with respect to lateral force, can be improved. Furthermore, since the slick portion <NUM> a has no groove element, it contributes to the suppression of tire noise, specifically, pass-by noise (PBN).

That is, the pneumatic tire <NUM> can achieve both the suppression of tire noise and the high rigidity with respect to lateral force, while allowing the vehicle to travel at an ultrafast speed including a wet road surface.

In this embodiment, the outside center land portion <NUM> has the slick portion <NUM> a in which the surface of the outside center land portion <NUM> is slick in the region of outside in the outside center land portion <NUM> when mounted to the vehicle. Therefore, the slick portion <NUM> a can be located in the ground contacting area CA of the outside of the tread portion <NUM> on the basis of the tire equatorial line CL when mounted to the vehicle. Since the slick portion <NUM> a has no groove element, the rigidity of the outside center land portion <NUM>, in particular, the rigidity with respect to lateral force, can be improved. Further, since the slick portion <NUM> a has no groove element, it contributes to the suppression of the PBN. Thus, the suppression of tire noise and the high rigidity with respect to lateral force can be made compatible in a higher dimension.

In this embodiment, the outside shoulder land portion <NUM> has a slick portion <NUM> a in which the surface of the outside shoulder land portion <NUM> is slick in the region of inside in the outside shoulder land portion <NUM> when mounted to the vehicle. Therefore, the slick portion <NUM> a can be located in the ground contacting area CA of the outside of the tread portion <NUM> on the basis of the tire equatorial line CL when mounted to the vehicle. Since the slick portion <NUM> a has no groove element, the rigidity of outside center land portion <NUM>, in particular, the rigidity with respect to lateral force, can be improved. Further, since the slick portion <NUM> a has no groove element, it contributes to the suppression of the PBN. Thus, the suppression of tire noise and the high rigidity with respect to lateral force can be made compatible in a higher dimension.

Further, by providing the slick portion <NUM> a, the slick portion <NUM> a, and the slick portion <NUM> a from inside to outside when mounted to the vehicle, the grip, particularly on the dry road surface, can be effectively improved.

In this embodiment, the plurality of lug grooves <NUM> inclined with respect to the tire width direction are formed along the tire width direction in the outside shoulder land portion <NUM>. Since the lug groove <NUM> is inclined with respect to the tire width direction along the tire width direction, the lug groove <NUM> contributes to the improvement of the drainability without greatly reducing the rigidity of the outside shoulder land portion <NUM>. If the lug groove <NUM> is largely inclined with respect to the tire width direction, the rigidity of the outside shoulder land portion <NUM> is greatly reduced and is not preferable.

Since the lug groove <NUM> is not parallel to the tire width direction, tire noise generated when the lug groove <NUM> comes into contact with the road surface can also be suppressed. Further, by forming the lug groove <NUM>, the outside shoulder land portion <NUM> around the lug groove <NUM> is easily deformed, and the grounding property of the outside shoulder land portion <NUM> located in the ground contacting area CA is improved. This can further improve the grip, especially on the dry road surface.

In the present embodiment, the width direction sipe <NUM> (also the width direction sipe <NUM> and the width direction sipe <NUM>) is formed by the width direction groove wall portion <NUM> extending in the tire width direction, the width direction groove wall portion <NUM> extending in the tire width direction and extending from the width direction groove wall portion <NUM> to the center side of the inside center land portion <NUM>, and the linear circumferential groove wall portion <NUM> communicating to the width direction groove wall portion <NUM> and the width direction groove wall portion <NUM>.

For this reason, one end (which may be referred to as the tip) of the width direction sipe <NUM> is communicated in such a state that the circumferential groove wall portion <NUM> is inclined rather than perpendicular to the width direction groove wall portion <NUM> and the width direction groove wall portion <NUM>, and is shaped like the tip of a sword. As a result, it is possible to suppress the occurrence of cracks starting at a position where the circumferential groove wall <NUM> is communicated to the widthwise groove wall <NUM> and the widthwise groove wall <NUM>.

In this embodiment, the outside shoulder land portion <NUM> has the groove wall portion <NUM>, the outside center land portion <NUM> has the groove wall portion <NUM>, and the inside center land portion <NUM> has the groove wall portion <NUM>.

The groove wall portion <NUM>, the groove wall portion <NUM>, and the groove wall portion <NUM> are inclined toward inside in the tire radial direction to approach inside when mounted to the vehicle , and the groove wall portion <NUM> is inclined more than the groove wall portion <NUM>. Therefore, the groove wall portion <NUM> contributes to increase the rigidity with respect to the input of lateral force from outside to the outside shoulder land portion <NUM> when mounted to the vehicle.

Further, in the present embodiment, the groove wall portion <NUM> is inclined more than the groove wall portion <NUM>. Therefore, the groove wall portion <NUM> can achieve a certain degree of rigidity improvement with respect to the input of lateral force from outside to the outside center land portion <NUM> when mounted to the vehicle, while securing the drainability.

In this embodiment, the slick portion <NUM> a is located within the ground contacting area CA. Further, the width of the lug groove <NUM> in the ground contacting area CA along the tire width direction is wider than the width of the slick portion <NUM> a along the tire width direction. Thus, while the grip of the slick portion <NUM> a on the dry road surface is secured, the drainability in the ground contacting area of the outside shoulder land portion <NUM> can be secured, and in particular, it can contribute to the improvement of vehicle dynamics on the wet road surface.

In this embodiment, the sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM>, and the circumferential groove <NUM> is larger than the width of outside center land portion <NUM> along the tire width direction. The sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM> and the circumferential groove <NUM> is wider than the width of the inside center land portion <NUM> along the tire width direction.

Thus, the plurality of slick portions in the ground contacting area CA can achieve a high degree of rigidity improvement with respect to lateral force and PBN suppression while surely securing the drainability necessary for the traveling of the vehicle mounted with the ultra-high performance tire such as the pneumatic tire <NUM>.

Although the contents of the present invention have been described above in accordance with the embodiments it would be obvious to those skilled in the art that various modifications and improvements are possible, the invention being limited to the scope defined by the claims.

For example, in the pneumatic tire <NUM>, three circumferential grooves are formed in the tread portion <NUM>, but four or more circumferential grooves may be formed in the tread portion <NUM>. The circumferential groove to be added may be a circumferential narrow groove narrower than the width of the circumferential groove <NUM>, the circumferential groove <NUM> and the circumferential groove <NUM>.

In the pneumatic tire <NUM>, the circumferential groove <NUM>, the circumferential groove <NUM>, and the circumferential groove <NUM> are perfectly linear, but may be formed so as to meander a little in the tire width direction as long as the entire circumferential groove extends in the tire circumferential direction.

In the pneumatic tire <NUM>, the sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM> and the circumferential groove <NUM> is wider than the width of the outside center land portion <NUM> along the tire width direction, and the sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM> and the circumferential groove <NUM> is wider than the width of the inside center land portion <NUM> along the tire width direction, but either or both of these relationships may not be satisfied.

In the pneumatic tire <NUM>, the sum of the groove widths of the circumferential groove <NUM>, the circumferential groove <NUM>, and the circumferential groove <NUM> is smaller than the widths of the slick portion <NUM> a, the slick portion <NUM> a, and the slick portion <NUM> a along the tire width direction, but such a relationship may not be satisfied.

Part of the land portion and the groove elements (including sipes) constituting the pneumatic tire <NUM> may not necessarily be as shown in <FIG>.

Claim 1:
A tire (<NUM>) having a tread portion (<NUM>) in which a plurality of linear circumferential grooves extending in tire circumferential direction are formed, wherein
the circumferential grooves include:
a first circumferential groove (<NUM>);
a second circumferential groove (<NUM>) formed in inside when mounted to a vehicle than the first circumferential groove (<NUM>); and
a third circumferential groove (<NUM>) formed in inside when mounted to the vehicle than the second circumferential groove (<NUM>),
the second circumferential groove (<NUM>) and the third circumferential groove (<NUM>) are formed in inside when mounted to the vehicle than a tire equatorial line (CL), wherein
the tread portion (<NUM>) is provided with:
an outside center land portion (<NUM>) provided between the first circumferential groove (<NUM>) and the second circumferential groove (<NUM>);
an inside center land portion (<NUM>) provided between the second circumferential groove (<NUM>) and the third circumferential groove (<NUM>);
an inside shoulder land portion (<NUM>) formed in inside when mounted to the vehicle than the third circumferential groove (<NUM>), wherein
a plurality of linear width direction sipes (<NUM>, <NUM>, <NUM>) inclined with respect to the tire width direction along the tire width direction are formed in the outside center land portion (<NUM>) and the inside center land portion (<NUM>), and
the inside shoulder land portion (<NUM>) has an inside slick portion (60a) in which a surface of the inside shoulder land portion (<NUM>) is slick in a grounding region of the inside shoulder land portion (<NUM>) in a state where normal load is loaded on the tire (<NUM>), wherein the outside center land portion (<NUM>) includes a center slick portion (40a) in which a surface of the outside center land portion (<NUM>) is slick in a region of outside of the outside center land portion (<NUM>),
the center slick portion (40a) is formed in a region of outside in the outside center land portion (<NUM>) when mounted to the vehicle,
characterized in that
a width of the center slick portion (40a) along the tire width direction is larger than a width of a portion in the outside center land portion (<NUM>) where width direction sipes (<NUM>) are formed along the tire width direction.