JP2019084966A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that is able to achieve both inhibition of deterioration of rolling resistance and reduction of road noise while improving wet steering stability.SOLUTION: A pneumatic tire, which is mounted on a vehicle so as to rotate in a specified rotational direction, comprises: two center main grooves 31; one shoulder main groove 35; a center main-groove-side shoulder groove part 24 formed on a shoulder land part 23 sectioned by the center main grooves 31; and a plane part 70 provided between the shoulder main groove 35 and each center main groove 31 and between the center main groove 31 sectioning the shoulder land part 23 and the center main-groove-side shoulder groove part 24, the plane part being an area where no grooves are formed over the entire circumference in a tire circumferential direction. At least part of the plane part 70 is located in the range of 22% or more but 38% or less of a ground width TW in a tire width direction form a tire equator surface CL. The total width, in the tire width direction, of the plane part is in the range of 10% or more but 30% or less of the ground width TW.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  In pneumatic tires, a plurality of grooves are formed on the tread surface for the purpose of draining water between the tread surface and the road surface when traveling on a wet road surface, but the grooves on the tread surface have steering stability and resistance It greatly affects the performance other than drainage, such as wear resistance and ride comfort. Therefore, in the conventional pneumatic tire, for example, as in Patent Documents 1 to 3, the balance of the performance required for the pneumatic tire is achieved by devising the groove position, the groove shape, the groove width, etc. There is.

JP, 2017-47853, A JP, 2014-184828, A JP, 2015-131603, A

  Here, in recent years, in order to improve the fuel consumption at the time of vehicle traveling, there is an increasing demand for reducing the rolling resistance at the time of rolling of the pneumatic tire. One way to reduce the rolling resistance is to reduce the rubber volume of the tread portion. However, when the rubber volume of the tread portion is reduced, the rigidity of the tread portion is reduced, so that the tread portion is easily bent, and road noise which is noise generated due to the unevenness of the road surface may be increased. Specifically, among road noises, it is known that the medium frequency band of 250 Hz to 315 Hz is affected by the vibration of the tread portion or the like when the pneumatic tire rolls, and the medium frequency road noise is a tread portion etc. The influence of the cross-section second-order eigenfrequency at the time of vibration is large. For this reason, when the rubber volume of the tread portion is reduced paying attention only to the reduction of the rolling resistance, there is a possibility that the cross-sectional second-order natural frequency becomes low due to the reduction of the rubber volume, and the road noise becomes large.

  On the other hand, reducing this road noise is also one of the important performances required of pneumatic tires. As a method for reducing the road noise, for example, adjusting the vibration state of the tread portion by adjusting the structural aspect such as adjusting the belt stiffness may be mentioned. However, when the adjustment of the structural surface is performed to reduce the road noise, the rolling resistance may be increased due to the change in rigidity.

  In addition, when the structural surface of the pneumatic tire is adjusted, the effect of the adjustment affects the various performances of the pneumatic tire, so when adjusting the structural surface to reduce road noise, the tread surface There is also a possibility that the wet steering stability, which is the steering stability on a wet road surface, which is a performance required for the formed groove, may be affected. For example, when improving the wet steering safety by devising the form of the groove, when the structure surface is adjusted to reduce road noise, the grounding shape on the road surface is suitable for improving the wet steering safety. There is a risk that it will not be possible to obtain the desired wet steering stability. As described above, it has been very difficult to reduce road noise while securing other performances such as rolling resistance and wet handling.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a pneumatic tire capable of achieving both suppression of deterioration of rolling resistance and reduction of road noise while improving wet handling. To aim.

  In order to solve the problems described above and to achieve the object, a pneumatic tire according to the present invention is an air mounted on the vehicle so as to rotate in a designated rotation direction about a rotation axis when the vehicle advances. A tire including two center main grooves formed one on each side of the tire width direction center line of the tread surface and extending in the tire circumferential direction and the tire width direction outside of the center main groove of the tread surface One shoulder main groove to be formed, a plurality of land portions defined by the center main groove and the shoulder main groove, and a side on which the shoulder main groove is located among the two center main grooves The land portion located on the opposite side of the center main groove in the tire width direction and the shoulder main groove on the tire width direction outside of the opposite side, and defined by the center main groove or the shoulder main groove Shoulder land portion formed by the shoulder main groove and the shoulder main groove side shoulder groove portion which extends in the tire width direction and whose inner end in the tire width direction communicates with the shoulder main groove And a center main groove side shoulder groove portion formed on the shoulder land portion defined by the center main groove and separated from the center main groove, the shoulder main groove, and the center main groove adjacent to the shoulder main groove. And between the center main groove defining the shoulder land portion and the center main groove side shoulder groove portion, and is a region in which no groove is formed over the entire circumferential direction of the tire. A plane portion, and the plane portion is in the range of 22% to 38% of the contact width in the tire width direction from the tire width direction center line And at least partially located in said plane section, characterized in that the total width in the tire width direction of the plurality of the plane portion is in the range of 30% more than 10% of the ground contact width.

  Further, in the pneumatic tire, it is preferable that a width of the plain portion in a tire width direction is in a range of 5% to 15% of the contact width.

  Further, in the pneumatic tire, the shoulder main groove is located at a position where the distance from the tire width direction center line to the groove width center of the shoulder main groove is within a range of 35% to 45% of the contact width. The center main groove is disposed at a position where the distance from the tire width direction center line to the groove width center of the center main groove is in the range of 10% to 20% of the contact width. The groove width of the shoulder main groove and the center main groove is in the range of 5% to 9% of the contact width, and the tread surface excludes the center main groove and the shoulder main groove. The groove area ratio of the grooves is preferably in the range of 2% to 10%.

  Further, in the pneumatic tire, a plain portion inner groove portion is formed between the plain portion and the center main groove, in which the inner end portion in the tire width direction communicates with the center main groove while extending in the tire width direction. Preferably, the plain portion is provided on the outer side in the tire width direction from the position in the tire width direction of the outer end portion of the plain portion inner groove portion in the tire width direction.

  Further, in the pneumatic tire, it is preferable that a sipe extending in the tire width direction and communicated with the main groove is formed in the land portion disposed between the center main grooves.

  In the pneumatic tire, the tire extends in the tire width direction between the plane portion and the center main groove and between the center main grooves and at least one end in the tire width direction communicates with the main groove. The plurality of sipes are disposed in the tire circumferential direction, and the plurality of sipes extend in the tire width direction and incline in the tire circumferential direction with respect to the tire width direction, and When going from the tire width direction center line side to the tire width direction outer side, the directions toward the tire circumferential direction are all inclined in the same direction, and the plurality of sipes are adjacent to each other through the center main groove It is preferable that the sipes which are formed in and communicate with the same center main groove are disposed at positions extending along each other.

  Further, in the pneumatic tire, the center main groove side shoulder groove portion and the shoulder main groove side shoulder groove portion respectively have a plurality of shoulder lug grooves extending in the tire width direction, and the shoulder lug grooves adjacent in the tire circumferential direction It is preferable to have the shoulder sipe arrange | positioned between and extending in the tire width direction.

  Further, in the pneumatic tire, it is preferable that a recess is formed on the shoulder land portion at the tire width direction outer side of the ground contact end.

  Further, in the pneumatic tire, it is preferable that a direction in which the pneumatic tire is attached to a vehicle be specified, and the shoulder main groove be formed inward in the vehicle attachment direction from the center main groove.

  Further, in the pneumatic tire, it is preferable that a groove area ratio of a total of the center main groove and the shoulder main groove in the tread surface is in a range of 20% to 35%.

  ADVANTAGE OF THE INVENTION The pneumatic tire which concerns on this invention has an effect that suppression of the deterioration of rolling resistance and reduction of road noise can be made compatible, improving wet handling property.

FIG. 1 is a meridional cross-sectional view showing the main parts of the pneumatic tire according to the embodiment. FIG. 2 is a plan view of the tread portion of the pneumatic tire shown in FIG. FIG. 3 is a detailed view of part A of FIG. FIG. 4 is an explanatory view of the positional relationship between the inter-main groove sipe shown in FIG. 3 and the plane portion inner sipe. FIG. 5 is an explanatory view of the widths and positions of the main groove and the plane portion shown in FIG. FIG. 6 is an explanatory view showing the relationship between the tread pattern shown in FIG. 2 and the magnitude of the amplitude in the cross-section second-order natural vibration mode. FIG. 7A is a chart showing the results of performance tests of pneumatic tires. FIG. 7B is a chart showing the results of performance tests of pneumatic tires. FIG. 7C is a chart showing the results of performance tests of pneumatic tires.

  Below, an embodiment of a pneumatic tire concerning the present invention is described in detail based on a drawing. The present invention is not limited by this embodiment. Further, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art and those that are substantially the same.

[Embodiment]
In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, the tire radial inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial outer side Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a circumferential direction with the rotation axis as a central axis. The tire width direction means a direction parallel to the rotation axis, the tire width direction inner side in the tire width direction toward the tire equatorial plane (tire equator line) CL, and the tire width direction outer side in the tire width direction It says the side away from tire equatorial plane CL. The tire equatorial plane CL is a plane perpendicular to the rotation axis of the pneumatic tire 1 and passing through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL is the center of the pneumatic tire 1 in the tire width direction. The position in the tire width direction coincides with the center line in the tire width direction which is the position. The tire width is the width in the tire width direction of the portions positioned outermost in the tire width direction, that is, the distance between the portions most distant from the tire equatorial plane CL in the tire width direction. The tire equator line is a line which is on the tire equator plane CL and extends along the circumferential direction of the pneumatic tire 1.

  FIG. 1 is a meridional cross-sectional view showing the main parts of the pneumatic tire 1 according to the embodiment. Here, in the pneumatic tire 1 shown in FIG. 1, the mounting direction with respect to the vehicle, that is, the direction at the time of vehicle mounting is designated. That is, in the pneumatic tire 1 shown in FIG. 1, the side facing inward of the vehicle when mounted on the vehicle is the inner side in the vehicle mounting direction, and the side facing outward of the vehicle when mounted on the vehicle is the outer side in the vehicle mounting direction. The designation of the inside of the vehicle mounting direction and the outside of the vehicle mounting direction is not limited to the case where the vehicle is mounted. For example, when the rim is assembled, the direction of the rim with respect to the inside and the outside of the vehicle is determined in the tire width direction. Therefore, when the pneumatic tire 1 is assembled in the rim, the vehicle mounting direction inner side and the vehicle in the tire width direction The mounting direction is specified with respect to the outside. The pneumatic tire 1 also has a mounting direction indicator (not shown) that indicates the mounting direction of the vehicle. The mounting direction display unit is configured of, for example, a mark or unevenness provided on the sidewall portion 4 of the tire. For example, ECER 30 (European Economic Commission Regulations Article 30) requires that the side wall 4 which is on the outer side in the vehicle mounting direction in the vehicle mounting state be provided with the mounting direction display. Moreover, the pneumatic tire 1 according to the present embodiment is a pneumatic tire 1 mainly used for a passenger car.

  Further, the pneumatic tire 1 according to the present embodiment is the pneumatic tire 1 in which the rotational direction at the time of wearing the vehicle is designated, that is, the rotational direction designated about the rotational axis at the time of forward movement of the vehicle. The pneumatic tire 1 is mounted on a vehicle so as to rotate. The pneumatic tire 1 also has a rotation direction indicator (not shown) that indicates the rotation direction. The rotation direction display unit is configured by, for example, a mark or unevenness provided on the sidewall portion 4 of the tire. In the following description, the first arrival side in the tire rotation direction is the rotation direction side when the pneumatic tire 1 is rotated in the designated direction, and the pneumatic tire 1 is mounted on a vehicle and rotated in the designated direction to travel In this case, it is the side that contacts the road surface first or leaves the road surface first. Further, the rear attachment side in the tire rotational direction is the opposite side of the rotational direction when the pneumatic tire 1 is rotated in the designated direction, and the pneumatic tire 1 is mounted on a vehicle and rotated in the designated direction to travel In this case, it is a side where it comes in contact with the road surface after the part located on the first arrival side, or leaves the road surface after the part located on the first arrival side.

  The pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both sides of the tread portion 2, and sidewall portions 4 and bead portions 5 which are sequentially connected from the shoulder portions 3. The pneumatic tire 1 further includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

  The tread portion 2 is made of a rubber material (tread rubber), and is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the outer peripheral surface thereof becomes the contour of the pneumatic tire 1. The outer peripheral surface of the tread portion 2 is configured as a tread surface 10 which is a surface that can contact the road surface mainly during traveling.

  The shoulder portions 3 are portions of the tread portion 2 on both outer sides in the tire width direction. Further, the sidewall portion 4 forms a portion of the pneumatic tire 1 that is exposed to the outermost side in the tire width direction. Further, the bead portion 5 has a bead core 15 and a bead filler 16. The bead core 15 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 16 is a rubber material disposed in a space formed by the end in the tire width direction of the carcass layer 6 being folded back at the position of the bead core 15.

  The carcass layer 6 has its tire width direction end portions folded back from the inside in the tire width direction to the outside in the tire width direction by a pair of bead cores 15 and wound in a toroidal shape in the tire circumferential direction to form a tire skeleton. It is a thing. The carcass layer 6 is obtained by coating a plurality of carcass cords (not shown) arranged side by side at an angle in the tire circumferential direction while the angle with respect to the tire circumferential direction is along the tire meridian direction, with a coat rubber. The carcass cord is made of, for example, an organic fiber such as polyester, rayon or nylon. The carcass layer 6 is provided in at least one layer.

  The belt layer 7 has a multi-layered structure in which at least two layers of belts 7a and 7b are stacked, and is disposed on the tread radial direction outer side of the carcass layer 6 in the tread portion 2 and covers the carcass layer 6 in the tire circumferential direction It is. The belts 7a and 7b are obtained by coating a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20 ° to 30 °) with the circumferential direction of the tire with a coated rubber. The cord is made of, for example, steel or an organic fiber such as polyester, rayon or nylon. The overlapping belts 7a and 7b are arranged such that their cords cross each other.

  The belt reinforcing layer 8 is disposed on the outer side in the tire radial direction, which is the outer periphery of the belt layer 7, and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is one in which a plurality of cords (not shown) substantially parallel to the tire circumferential direction and arranged in parallel in the tire width direction are coated with a coat rubber. The cord is made of, for example, steel or an organic fiber such as polyester, rayon or nylon, and the angle of the cord is within ± 5 ° with respect to the tire circumferential direction. The belt reinforcing layer 8 shown in FIG. 1 is disposed so as to cover the end of the belt layer 7 in the tire width direction. The configuration of the belt reinforcing layer 8 is not limited to the above and is not clearly shown in the drawings, but is configured to cover the entire belt layer 7 or has, for example, two reinforcing layers, The reinforcing layer is formed to be larger in the tire width direction than the belt layer 7 and arranged to cover the entire belt layer 7, and the reinforcing layer on the outer side in the tire radial direction is arranged to cover only the tire width direction end of the belt layer 7 Alternatively, for example, two reinforcing layers may be provided, and each reinforcing layer may be disposed so as to cover only the end portion of the belt layer 7 in the tire width direction. That is, the belt reinforcing layer 8 overlaps at least the tire width direction end of the belt layer 7. Further, the belt reinforcing layer 8 is provided by winding a strip material having a width of, for example, about 10 mm in the tire circumferential direction.

  FIG. 2 is a plan view of the tread portion 2 of the pneumatic tire 1 shown in FIG. Three main grooves 30 extending in the tire circumferential direction are formed on the tread surface 10 of the tread portion 2. The three main grooves 30 are arranged on the outer side in the tire width direction of one of the center main grooves 31 of the center main groove 31 and one of the two center main grooves 31 arranged one on each side of the tire equatorial plane CL. And one shoulder main groove 35. The two center main grooves 31 arranged on both sides of the tire equatorial plane CL have substantially the same distance from the tire equatorial plane CL in the tire width direction, and the shoulder main groove 35 has one center main groove 31 and the ground terminal T. That is, all the three main grooves 30 are disposed on the inner side in the tire width direction of the ground contact end T. Further, in the pneumatic tire 1 according to the present embodiment, the mounting direction with respect to the vehicle is designated, and the shoulder main groove 35 is formed inward of the center main groove 31 in the vehicle mounting direction.

  In this case, the ground contact end T is formed by rimming the pneumatic tire 1 on a regular rim and filling with a regular internal pressure, and the load is equivalent to 88% of the regular load, placed perpendicular to the flat plate in a stationary state. And the outermost ends in the tire width direction of the region in contact with the flat plate in the tread surface 10, and is continuous in the tire circumferential direction.

  Here, the normal rim is a “standard rim” defined by JATMA, a “design rim” defined by TRA, or a “measuring rim” defined by ETRTO. The normal internal pressure is the "maximum air pressure" defined by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFlation PRESSURES" defined by TRA, or "INFLATION PRESSURES" defined by ETRTO. The normal load is the maximum value of "maximum load capacity" defined by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or "LOAD CAPACITY" defined by ETRTO.

  Further, the main groove 30 refers to a vertical groove at least a part of which extends in the tire circumferential direction. Generally, the main groove 30 has a groove width of 5 mm or more, a groove depth of 7.5 mm or more, and internally has a tread wear indicator (slip sign) indicating the end of wear. In the present embodiment, the main groove 30 has a groove width of 5 mm or more, a groove depth of 5 mm or more, and the tire equator line (center line) where the tire equator surface CL intersects with the tread surface 10 And substantially parallel. The main groove 30 may extend linearly in the tire circumferential direction, or may be provided in a wave shape or zigzag.

  Further, a plurality of land portions 20 defined by the main grooves 30 of the center main groove 31 and the shoulder main groove 35 are formed on the tread surface 10. As land part 20, center land part 21 which is land part 20 located between two center main grooves 31 and land part 20 located between adjacent center main groove 31 and shoulder main groove 35 The tire width direction outer side of the center main groove 31 located on the opposite side of the side where the shoulder main groove 35 is located among the second land portion 22 and the two center main grooves 31 and the tire width direction outer side of the shoulder main groove 35 And a shoulder land portion 23 which is a land portion 20 defined by the center main groove 31 or the shoulder main groove 35.

  In other words, the center land portion 21 has both side ends in the tire width direction defined by the two center main grooves 31, and the second land portion 22 has both side ends in the tire width direction the center main groove 31 and the shoulder main The shoulder land portion 23 is defined by the groove 35, and an inner end portion in the tire width direction is defined by the center main groove 31 or the shoulder main groove 35. That is, among the land portions 20, the shoulder land portion 23 has a center main groove side shoulder land portion 24 whose inner end portion in the tire width direction is formed by the center main groove 31, and an inner end portion in the tire width direction. And a shoulder main groove side shoulder land portion 25 defined by the shoulder main groove 35. All of the land portions 20 are formed as rib-like land portions 20 extending in the tire circumferential direction.

  Among the land portions 20 defined by the main groove 30 as described above, the center main groove side shoulder which is a groove formed to be separated from the center main groove 31 is formed on the center main groove side shoulder land portion 24. A groove 41 is formed, and the shoulder main groove side shoulder land portion 25 extends in the tire width direction and the shoulder main groove side shoulder is a groove whose inner end in the tire width direction communicates with the shoulder main groove 35 A groove 43 is formed. The center main groove side shoulder groove portion 41 and the shoulder main groove side shoulder groove portion 43 are respectively disposed between a plurality of shoulder lug grooves 46 extending in the tire width direction and the shoulder lug grooves 46 adjacent in the tire circumferential direction. And a shoulder sipe 47 which is a sipe extending in the tire width direction. That is, the shoulder lug grooves 46 and the shoulder sipes 47 respectively provided by the center main groove side shoulder groove portion 41 and the shoulder main groove side shoulder groove portion 43 have a plurality of shoulder lug grooves 46 and shoulder sipes 47 alternately in the tire circumferential direction. It is arranged.

  The sipe referred to here is a groove formed in a narrow groove shape on the tread surface 10, and the pneumatic tire 1 is rim-assembled on a normal rim, and the narrow groove is formed under no load condition under normal internal pressure conditions. When the narrow groove is positioned on the portion of the ground contact surface formed on the flat plate when the wall surfaces are not in contact with each other but are loaded in the vertical direction on the flat plate, or when the land portion 20 in which the narrow groove is formed falls. The wall surfaces constituting the narrow groove, or at least a part of the portion provided on the wall surfaces are in contact with each other due to the deformation of the land portion 20.

  The shoulder lug grooves 46 and the shoulder sipes 47 are both curved in the tire circumferential direction with respect to the tire width direction while extending in the tire width direction. The shoulder lug grooves 46 and the shoulder sipes 47 are both curved in the direction in which the inclination angle with respect to the tire width direction decreases as going from the inside to the outside in the tire width direction. Further, the shoulder lug grooves 46 and the shoulder sipes 47 formed in the center main groove side shoulder land portion 24 and the shoulder main groove side shoulder land portion 25 respectively extend in the tire circumferential direction when going from the inside to the outside in the tire width direction. The directions to go at are all the same. That is, the shoulder lug grooves 46 and the shoulder sipes 47 are all inclined toward the same direction in the tire circumferential direction as they go from the inside to the outside in the tire width direction. In the present embodiment, the shoulder lug grooves 46 and the shoulder sipes 47 are inclined in the direction from the front to the rear in the tire rotation direction from the inside to the outside in the tire width direction.

  Further, in the shoulder lug groove 46 of the center main groove side shoulder groove portion 41, the inner end 46a of the shoulder lug groove 46 in the tire width direction terminates in the center main groove side shoulder land portion 24, and the outer end in the tire width direction The portion 46 b is open at the design end E which is the tire width direction outer end of the tread surface 10. On the other hand, in the shoulder sipe 47 of the center main groove side shoulder groove portion 41, the inner end 47a and the outer end 47b both end in the center main groove side shoulder land portion 24 in the tire width direction. The shoulder lug groove 46 and the shoulder sipe 47 of the center main groove side shoulder groove portion 41 have a position in the tire width direction of the inner end 46 a of the shoulder lug groove 46 in the tire width direction, and a tire width direction of the shoulder sipe 47 The position of the inner end portion 47a in the tire width direction is substantially the same position.

  Here, the design end E is the tire width direction outer side of the ground contact end T, and refers to the tire width direction outermost end of the tread portion 2, and is the tire width direction outermost end where grooves are formed in the tread portion 2. In FIG. 2, the design end E is continuously shown in the tire circumferential direction. That is, on the dry and flat road surface, the tread portion 2 is a region on the design end E side of the ground contact end T, which is a region not normally in contact with the road surface.

  Further, in the shoulder lug groove 46 of the shoulder main groove side shoulder groove portion 43, the inner end 46a of the shoulder lug groove 46 in the tire width direction communicates with the shoulder main groove 35, and the outer end 46b in the tire width direction is the design end Opening at E The shoulder sipe 47 of the shoulder main groove side shoulder groove 43 communicates with the shoulder main groove 35 at the inner end 47a in the tire width direction, and the outer end 47b in the tire width direction is the shoulder main groove side shoulder land 25 Terminated within. That is, the shoulder lug grooves 46 and the shoulder sipe 47 of the shoulder main groove side shoulder groove portion 43 both communicate with the shoulder main groove 35 with the inner end portions 46 a and 47 a in the tire width direction.

  The shoulder lug groove 46 formed as described above has a groove width of 1.5 mm to 8 mm, and a groove depth of 2 mm to 8 mm. The shoulder sipe 47 has a groove depth of 2 mm or more and 8 mm or less within a range of 0.1 mm or more and 2 mm or less.

  FIG. 3 is a detailed view of part A of FIG. In the vicinity of the center main groove 31 in the center main groove side shoulder land portion 24 and in the vicinity of the center main groove 31 in the second land portion 22, a plane portion inner groove portion 50 defining a plane portion 70 described later is formed. . In the present embodiment, the plane portion inner groove portion 50 is formed by the plane portion inner sipe 51 formed as a sipe. The plain inner side sipe 51 is inclined in the tire circumferential direction with respect to the tire width direction while extending in the tire width direction, and the inclination direction in the tire circumferential direction is a shoulder formed in the center main groove side shoulder land portion 24 The direction is the same as the inclination direction of the lug grooves 46 and the shoulder sipes 47.

  Further, in the plain inner side sipe 51 formed on the center main groove side shoulder land portion 24, the inner end 51a in the tire circumferential direction communicates with the center main groove 31, and the outer end 51b in the tire circumferential direction is the center It terminates in the main groove side shoulder land portion 24. The outer end 51 b of the plain inner side sipe 51 formed on the center main groove side shoulder land portion 24 is the inner end 46 a of the shoulder lug groove 46 of the center main groove side shoulder groove 41 and the inner end of the shoulder sipe 47. It is located in the tire width direction inside rather than the position in the tire width direction of part 47a.

  In the center main groove side shoulder land portion 24, the inner end 46a of the shoulder lug groove 46 and the inner end 47a of the shoulder sipe 47 and the outer end 51b of the plain inner side sipe 51 are in the tire width direction as described above. Since the shoulder lug grooves 46 and the shoulder sipes 47 do not overlap with the plain inner side sipes 51 in the tire circumferential direction, the center main groove side shoulder land portion 24 is provided along the entire circumferential direction of the tire. A plane portion 70 is provided, which is an area over which no groove is formed. That is, the plain portion 70 provided in the center main groove side shoulder land portion 24 is disposed between the center main groove 31 and the center main groove side shoulder groove portion 41 which define the center main groove side shoulder land portion 24. There is.

  More specifically, the plain portion 70 provided in the center main groove side shoulder land portion 24 is directed from the position in the tire width direction of the outer end portion 51b of the plain portion inner sipe 51 toward the tire width direction outer side, center central groove side shoulder groove portion 41 is a range in the tire width direction up to the position in the tire width direction of the shoulder lug grooves 46 and the inner end portions 46a and 47a of the shoulder sipes 47, and provided in this range over the entire circumferential direction of the tire ing. In other words, the plain portion 70 provided in the center main groove side shoulder land portion 24 has the boundary in the tire width direction at the position in the tire width direction of the outer end 51b of the plain portion inner sipe 51, and the tire width direction The outer boundaries are positions in the tire width direction of the shoulder lug grooves 46 and the inner end portions 46 a and 47 a of the shoulder sipes 47. The plane inner side sipe 51 formed in the center main groove side shoulder land portion 24 is thus formed between the plane main portion 70 provided in the center main groove side shoulder land portion 24 and the center main groove 31, One end is in communication with the center main groove 31.

  Further, as with the plain inner side sipe 51 formed in the center main groove side shoulder land portion 24, the plain inner side sipe 51 formed in the second land portion 22 also has the center main groove 31 with the inner end 51 a in the tire circumferential direction. And the outer end 51 b in the tire circumferential direction terminates in the second land portion 22. The plain inner side sipe 51 formed in the second land portion 22 is separated inward in the tire width direction with respect to the shoulder main groove 35 by the outer end 51 b terminating in the second land portion 22.

  Also, the plain portion inner sipe 51 formed in the second land portion 22 is also inclined in the tire circumferential direction with respect to the tire width direction while extending in the tire width direction. The inclination direction of the plain inner side sipe 51 formed in the second land portion 22 in the tire circumferential direction is the same as the inclination direction of the shoulder lug groove 46 and the shoulder sipe 47 formed in the shoulder main groove side shoulder land portion 25 It has become. That is, in the plane portion inner sipe 51 formed in the center main groove side shoulder land portion 24 and the plane portion inner sipe 51 formed in the second land portion 22, the inclination directions in the tire circumferential direction with respect to the tire width direction are opposite to each other It is in the direction. In the present embodiment, similar to the shoulder lug grooves 46 and the shoulder sipes 47, the plain portion inner sipes 51 formed in the land portions 20 at two locations are first-come in the tire rotational direction as they go from the inside to the outside in the tire width direction. It is inclined in the direction from the side to the rear landing side.

  Since the outer end 51b of the plain inner side sipe 51 formed in the second land portion 22 is separated inward in the tire width direction from the shoulder main groove 35, the second land portion 22 also has the entire circumference in the tire circumferential direction. A plane portion 70 is provided, which is an area over which no groove is formed. That is, the plain portion 70 provided in the second land portion 22 defines the second land portion 22 with the shoulder main groove 35 adjacent to the shoulder main groove 35 defining the second land portion 22 and the shoulder main groove 35. It is disposed between the center main groove 31.

  More specifically, the plain portion 70 provided in the second land portion 22 is an inner edge at the opening of the shoulder main groove 35 from the position in the tire width direction of the outer end 51 b of the plain portion inner sipe 51 toward the tire width direction. It is a range in the tire width direction up to the position in the tire width direction of the part, and is provided over the entire circumference in the tire circumferential direction in this range. In other words, the plain portion 70 provided in the second land portion 22 has a boundary in the tire width direction at the position in the tire width direction of the outer end 51b of the plain portion inner sipe 51, and the boundary in the tire width direction is It is the position in the tire width direction of the inner edge at the opening of the shoulder main groove 35. The plane portion inner sipe 51 formed in the second land portion 22 is thus formed between the plane portion 70 provided in the second land portion 22 and the center main groove 31, and one end thereof communicates with the center main groove 31. doing.

  Further, in the center land portion 21 disposed between the center main grooves 31, a main groove inter-sipe 60, which is a sipe extending in the tire width direction and communicating with the center main groove 31, is formed. A plurality of inter-sipes 60 are disposed side by side in the tire circumferential direction. Both ends of the inter-main-groove sipe 60 are in communication with different center main grooves 31 respectively, and from the center in the tire width direction of the center land portion 21 toward the outer side in the tire width direction, It is inclined in the direction towards the landing side. That is, the inter-main-groove sipe 60 has a bent portion 65 in the vicinity of the center in the tire width direction of the center land portion 21 where the angle of inclination with respect to the tire width direction changes. As it goes to the outside, it is inclined in the direction from the first attachment side to the rear attachment side in the tire rotation direction. For this reason, in the inter-main-groove sipe 60, the position of the bending portion 65 is located closest to the front end in the tire rotation direction. In the present embodiment, the bending portion 65 of the inter-main groove sipe 60 is located on the tire equatorial plane CL.

  Further, since the inter-main-groove sipe 60 has the bending portion 65 in this manner, a portion on the side of the one main main groove 31 from the bending portion 65 in the main-inter-groove sipe 60 and the center main groove 31 The plane portion inner side sipe 51 that communicates is inclined in the same direction with respect to the tire width direction. That is, the inter-main groove sipe 60 and the plain portion inner sipe 51 extend in the tire width direction and are inclined in the tire circumferential direction with respect to the tire width direction, and go from the tire equatorial plane CL side toward the tire width direction outward. At the same time, the directions toward the tire circumferential direction are all inclined in the same direction.

  FIG. 4 is an explanatory view of the positional relationship between the inter-main groove sipe 60 and the plane portion inner sipe 51 shown in FIG. The inter-main-groove sipe 60 and the plain-portion inner sipe 51 which are formed in the center land portion 21 and the second land portion 22 adjacent to each other via the same center main groove 31 and communicate with the same center main groove 31 Are arranged at the Similarly, an inter-main-groove sipe 60 and a plain-portion inner sipe 51 which are formed in the center land portion 21 and the center main groove side shoulder land portion 24 adjacent to each other via the same center main groove 31 and communicate with the same center main groove 31. And are arranged at positions extending along each other. For this reason, when the inter-main-groove sipe 60 and the plane portion inner sipe 51 are located on an extended line with each other, the inter-main-groove sipe 60 and the plane portion inner sipe 51 are viewed as a whole. The bent portion 65 of the inter-main groove sipe 60 is formed in a V-shaped shape located on the tire equatorial plane CL.

  In other words, the inter-main-groove sipe 60 and the plain inner side sipe 51 are positioned on the tire equatorial plane CL with the bent portion 65 of the inter-main-groove sipe 60 at the apex of the V shape. It is formed in a V-shaped shape in which the width in the tire width direction becomes larger as it goes to the wearing side. As described above, the inter-main-groove sipe 60 formed in the center land portion 21 and the second land portion 22 adjacent to each other via the center main groove 31 is adjacent to each other via the plane portion inner sipe 51 and the center main groove 31. The inter-main groove sipe 60 and the plain inner side sipe 51 formed in the center land portion 21 and the center main groove side shoulder land portion 24 penetrate the center main groove 31 and the main groove inter-sipe 60 and the plain portion inner sipe 51 And so as to form a V-shape.

  As described above, the inter-main-groove sipe 60 formed in the center land portion 21 and the second land portion 22 adjacent to each other via the center main groove 31 is adjacent to each other via the plane portion inner sipe 51 and the center main groove 31. The inter-main-groove sipe 60 formed in the center land portion 21 and the center main groove side shoulder land portion 24 and the plane portion inner sipe 51 are formed to have a relationship of penetrating the center main groove 31. The inter-main groove sipe 60 and the plane portion inner sipe 51 formed in different land portions 20 are arranged with regularity as described above.

  The inter-main groove sipe 60 formed in the center land portion 21 and the plain portion inner sipe 51 formed in the second land portion 22 and the center main groove side shoulder land portion 24 each have a groove width of 0.1 mm to 2.0 mm. The groove depth is in the range of 2.0 mm or more and 8.0 mm or less within the following range. Further, the positional relationship in which the sipes are extended lines with each other means that the center line CS in the groove width direction of at least one of the two target sipes communicates with the same main groove 30 When extending toward the sipe side, the distance between the center lines CS of each sipe at the position where the other sipe communicates with the main groove 30 is within the range of 0 mm or more and 4.0 mm or less. Say.

  Further, in the shoulder land portions 23 on both sides in the tire width direction, recessed portions 80 recessed from the tread surface 10 are formed on the tire width direction outside of the ground contact end T, respectively. The recess 80 is provided near the design end E in the tread surface 10, and has a circular shape with a diameter of 0.1 mm or more and 1.0 mm or less within a range of 1.0 mm or more and 5.0 mm or less. Is formed in a dimple shape. The recessed portion 80 is disposed on the center main groove side shoulder land portion 24 and the shoulder main groove side shoulder land portion 25 respectively on the outer side in the tire width direction than the outer end portion 47 b of the shoulder sipe 47. That is, the recessed portions 80 formed in the center main groove side shoulder land portion 24 and the shoulder main groove side shoulder land portion 25 are respectively in the tire width direction in portions between the shoulder lug grooves 46 adjacent in the tire circumferential direction. The shoulder sipes 47 are not formed. In the present embodiment, the recesses 80 are arranged in two rows in each of the tire width direction and the tire circumferential direction between the shoulder lug grooves 46 adjacent to each other in the tire circumferential direction, that is, adjacent to each other in the tire circumferential direction Four are provided between the shoulder lug grooves 46 that fit together.

  FIG. 5 is an explanatory view of the widths and positions of the main groove 30 and the plane portion 70 shown in FIG. The groove width WGc of the center main groove 31 formed in the tread surface 10 is in the range of 5% to 9% of the contact width TW, and the groove width WGs of the shoulder main groove 35 is also the contact width TW 5% or more and 9% or less. Further, among the three main grooves 30, the center main grooves 31 disposed on both sides in the tire width direction of the tire equatorial plane CL have a distance DGc from the tire equatorial plane CL to the groove width center CGc of the center main groove 31, respectively. Is disposed at a position which falls within the range of 10% to 20% of the ground contact width TW. The shoulder main groove 35 is disposed at a position where the distance DGs from the tire equatorial plane CL to the groove width center CGs of the shoulder main groove 35 is in the range of 35% or more and 45% or less of the contact width TW. The ground contact width TW in this case is the distance between the ground contact ends T of the tread surface 10 in the tire width direction.

  On the other hand, at least a portion of the plain portions 70 provided on both sides of the tire equatorial plane CL in the tire width direction is in the range of 22% to 38% of the ground contact width TW in the tire width direction from the tire equatorial plane CL. ing. In the plane portion 70, the plane width WP, which is the width in the tire width direction, is in the range of 5% to 15% of the ground contact width TW, and the total width of the plurality of plane portions 70 in the tire width direction That is, the total width of the two plane portions 70 is in the range of 10% to 30% of the ground width TW. In the plane portion 70, the distance DP from the tire equatorial plane CL to the plane width center CP in the tire width direction of the plane portion 70 is within a range of 25% to 35% of the ground contact width TW. It is preferred to be located at

  As described above, in the tread surface 10 on which the grooves such as the main groove 30 are formed, the groove area ratio of the main groove 30, that is, the groove area ratio of the center main groove 31 and the shoulder main groove 35 is 20% or more The groove area ratio of the grooves excluding the center main groove 31 and the shoulder main groove 35 is in the range of 2% or more and 10% or less. Moreover, the groove area ratio which united all the grooves formed in the tread surface 10 is in the range of 20% or more and 35% or less. The groove area ratio here is defined by the percentage of groove area / (groove area + grounding area). The groove area is the sum of the opening areas of the grooves to be calculated in the ground plane (ground area). The groove area and the ground contact area are measured when the pneumatic tire 1 is rim-assembled on a regular rim, and the regular internal pressure is filled and 88% of the regular load is applied.

  When mounting the pneumatic tire 1 according to the present embodiment to a vehicle, the pneumatic tire 1 is mounted on the rim wheel by fitting the rim wheel to the bead portion 5 and the air is filled into the inside to fill the inside. Fit on the vehicle in a flat state. At that time, the pneumatic tire 1 according to the present embodiment is attached to the vehicle in the designated direction since the attachment direction to the vehicle is designated. Specifically, of the three main grooves 30 formed in the tread surface 10, the shoulder main groove 35 is mounted in the direction that is located most inward in the vehicle mounting direction.

  In addition, since the pneumatic tire 1 according to the present embodiment has a designated rotational direction, the pneumatic tire 1 is configured to rotate in the designated rotational direction as the pneumatic tire 1 rotates when the vehicle advances. Attach to the vehicle. Specifically, the sipe 60 between the main grooves, the inner side sipe 51, the shoulder lug groove 46, and the shoulder sipe 47, which are formed to be inclined in the tire circumferential direction with respect to the tire width direction, Each vehicle is attached to the vehicle in a direction in which the tire gradually comes in contact with the tire width direction outer side from the tire width direction inner side. Alternatively, the apex side of the V of the main groove between the main groove sipe 60 and the plane inner side sipe 51 disposed in an extended line with each other and disposed in a V shape when viewed as a whole is a tire It is mounted in the direction that is located on the first arrival side in the rotational direction. That is, the pneumatic tire 1 is mounted on the vehicle in such a direction that the direction of the sipe 60 between the main grooves is the direction in which the bent portion 65 is positioned on the front-end side in the tire rotation direction.

  When the vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the tread surface 10 of the portion of the tread surface 10 located below contacts the road surface. The vehicle travels by transmitting a driving force or a braking force to the road surface or generating a turning force by the frictional force between the tread surface 10 and the road surface. For example, when traveling on a dry road surface with a vehicle equipped with the pneumatic tire 1, the driving force or the braking force is transmitted to the road surface mainly by the frictional force between the tread surface 10 and the road surface, or the turning force Travel by generating or. In addition, when traveling on a wet road surface, water between the tread surface 10 and the road surface enters grooves such as the main groove 30 and the shoulder lug grooves 46, and these grooves cause the water to flow between the tread surface 10 and the road surface. Run while draining the water. As a result, the tread surface 10 easily contacts the road surface, and the frictional force between the tread surface 10 and the road surface enables the vehicle to travel as desired.

  Here, the three main grooves 30 formed in the tread surface 10 have two center main grooves 31 disposed one by one on both sides of the tire equatorial plane CL, and the tire width of one center main groove 31. It is comprised by one shoulder main groove 35 arrange | positioned by the direction outer side. Therefore, on both sides of the tire equatorial plane CL in the tire width direction of the tread surface 10, on the side where the shoulder main groove 35 is provided, drainage can be ensured by the center main groove 31 and the shoulder main groove 35. Therefore, the wet steering stability which is the steering stability when traveling on a wet road surface can be improved. Further, among the two sides of the tire equatorial plane CL in the tire width direction of the tread surface 10, only one main groove 30 is provided on the side opposite to the side on which the shoulder main groove 35 is provided, The rigidity of the land portion 20 defined by the main groove 30 can be secured. As a result, when the pneumatic tire 1 rolls, excessive deformation of the land portion 20 can be suppressed, and rolling resistance can be reduced.

  Further, in the pneumatic tire 1 according to the present embodiment, the rotational direction is specified, and the inter-main-groove sipes 60, the plain portion inner sipes 51, the shoulder lug grooves 46, and the shoulder sipes 47 formed in the tread surface 10 are At the time of rotation of the pneumatic tire 1, the tire is gradually grounded from the inside in the tire width direction toward the outside in the tire width direction. As a result, water between the tread surface 10 and the road surface can be drained from the tire equatorial plane CL side toward the tire width direction outer side by these sipes or the like as the pneumatic tire 1 rotates, and drainage performance As a result, wet handling can be further improved. Moreover, since the drainage property is secured by designating the rotation direction of the pneumatic tire 1 and arranging the grooves formed on the tread surface 10 with regularity, drainage is not performed without increasing the groove area ratio. As a result, the rigidity of the land portion 20 can be ensured while ensuring the drainage property. As a result, excessive deformation of the land portion 20 can be suppressed more reliably, and rolling resistance can be reduced.

  Further, on the tread surface 10, a plain portion 70 in which a groove is not formed is provided over the entire circumferential direction of the tire, and the plain portion 70 has a ground width TW in the tire width direction from the tire equatorial plane CL. At least a portion is located within the range of 22% to 38%. As a result, it is possible to stabilize the vibration due to the deformation of deflection during rolling of the pneumatic tire 1, and to suppress the increase in road noise due to the instability of the vibration.

  FIG. 6 is an explanatory view showing the relationship between the tread pattern shown in FIG. 2 and the magnitude of the amplitude in the cross-section second-order natural vibration mode. At the time of rolling of the pneumatic tire 1, the tread portion 2 is rotated while the tread portion 2 is repeatedly bent because the pneumatic tire 1 is rotated while repeating contact and separation of the tread surface 10 on the road surface. As a result, the tread portion 2 vibrates by repeating the amplitude in the form of a so-called steady wave due to the bending of the pneumatic tire 1 when rolling. Since the tread portion 2 vibrates in the form of a steady wave in this manner when the pneumatic tire 1 rolls, the amplitude of the vibration wave V of the tread portion 2 in the cross-section secondary natural vibration mode representing the vibration state of the tread portion 2 The size of V depends on the position in the tire width direction.

  The amplitude of the vibration wave V in the cross-section second-order natural vibration mode is the largest near the tire equatorial plane CL, as shown in FIG. 6, and decreases toward the tire width direction outer side from the tire equatorial plane CL. The distance from the center in the tire width direction in the range between the equatorial plane CL and the ground contact end T increases toward the tire width direction outer side. That is, in the cross-sectional second-order natural vibration mode, the so-called antinode Va of the stationary wave where the amplitude of the vibration wave V becomes largest is located near the tire equatorial plane CL, and in the range between the tire equatorial plane CL and the ground end T A node Vn at which the amplitude of the vibration wave V is the smallest is located near the center in the tire width direction. Further, the nodes Vn of the vibration wave V are located on both sides of the tire equatorial plane CL in the tire width direction, and the two nodes Vn are each 5% or more of the contact width TW in the tire width direction from the tire equatorial plane CL It is located within the range of 15% or less.

  At least a portion of the plain portion 70 of the tread surface 10 is located in the range of 22% to 38% of the ground contact width TW in the tire width direction from the tire equatorial plane CL. It is located at the node Vn of the vibration wave V in the natural vibration mode. Thus, the rigidity of the tread portion 2 in the vicinity of a position corresponding to the node Vn of the vibration wave V in the cross-section second-order natural vibration mode is high, and the tread portion 2 is hardly deformed at the position of the node Vn. That is, the plain portion 70 has high rigidity because no groove is formed over the entire circumference of the tire circumferential direction, and the position of the plain portion 70 in the tire width direction is the position of the node Vn in the tire width direction As a result, the deformation of the tread portion 2 at the position of the node Vn can be reduced. Therefore, when the pneumatic tire 1 rolls, it is possible to suppress that the tread portion 2 is easily vibrated at the node Vn of the vibration wave V in the cross-section secondary natural vibration mode, and the frequency of the cross-section secondary natural vibration mode Since the height can be increased, road noise can be reduced.

  Further, since the total width of the plurality of plain portions 70 in the tire width direction is in the range of 10% to 30% of the ground contact width TW in the plain portion 70, the tread portion 2 vibrates at the node Vn. It can be more reliably suppressed that it becomes easy to do. That is, when the total width of the plane portion 70 is less than 10% of the ground contact width TW, the total width of the plane portion 70 is too narrow, and it may be difficult to secure the rigidity of the tread portion 2 even if the plane portion 70 is provided. There is. In this case, even if the plane portion 70 is provided, it may be difficult to suppress the tendency of the tread portion 2 to easily vibrate at the node Vn of the cross-section secondary natural vibration mode. When the total width of the plane portion 70 exceeds 30% of the ground width TW, the total width of the plane portion 70 is too wide, so the rigidity of the tread portion 2 at a position other than the node Vn of the cross-section secondary natural vibration mode There is a possibility that the plane unit 70 may increase the pressure. In this case, since the difference between the rigidity at the node Vn of the cross-section second-order natural vibration mode in the tread portion 2 and the rigidity at positions other than the node Vn is reduced, the tread portion 2 In addition to the position other than the node Vn, there is a possibility that the vibration easily occurs at the position of the node Vn.

  On the other hand, when the total width of the plurality of plane portions 70 is in the range of 10% to 30% of the ground contact width TW, the rigidity at the position of the node Vn in the tread portion 2 is set to a position other than the node Vn. The rigidity of the node V can be more reliably increased, and the ease of vibration at the node V n can be more reliably suppressed. Thus, the frequency of the cross-sectional second-order natural vibration mode can be more reliably increased, and road noise can be reduced more reliably. As a result of these, it is possible to achieve both suppression of deterioration of rolling resistance and reduction of road noise while improving wet steering.

  Further, in the plane portion 70, since the plane width WP is in the range of 5% to 15% of the ground width TW, it is more reliably suppressed that the tread portion 2 easily vibrates at the node Vn. Can. That is, when the plane width WP of the plane portion 70 is less than 5% of the ground width TW, the plane width WP is too narrow, so even if the plane portion 70 is provided, it may be difficult to secure the rigidity of the tread portion 2 . In this case, even if the plane portion 70 is provided, it may be difficult to suppress the tendency of the tread portion 2 to easily vibrate at the node Vn of the cross-section secondary natural vibration mode. When the plane width WP of the plane portion 70 exceeds 15% of the ground width TW, the plane width WP is too wide, so the rigidity of the tread portion 2 at a position other than the node Vn of the cross-section secondary natural vibration mode is There is a possibility that it may be increased by 70. In this case, since the difference in rigidity between the position of the node Vn of the tread portion 2 and the position other than the node Vn is difficult to obtain, when the pneumatic tire 1 rolls, the tread portion 2 is not only at the position other than the node Vn. Also, there is a possibility that the vibration easily occurs even at the position of the node Vn.

  On the other hand, when the plane width WP of the plane portion 70 is in the range of 5% to 15% of the ground width TW, the rigidity at the position of the node Vn in the tread portion 2 is the rigidity of the position other than the node Vn In contrast, it is possible to more reliably suppress the tendency of the node Vn to vibrate more easily. As a result, the frequency of the cross-sectional second-order natural vibration mode can be more reliably increased, and road noise can be reduced more reliably.

  Further, the shoulder main groove 35 is disposed at a position where the distance DGs from the tire equatorial plane CL to the groove width center CGs of the shoulder main groove 35 is in the range of 35% to 45% of the contact width. The rigidity of the land portion 22 and the rigidity of the shoulder main groove side shoulder land portion 25 can be secured in a well-balanced manner. That is, when the distance DGs from the tire equatorial plane CL to the groove width center CGs of the shoulder main groove 35 is less than 35% of the ground contact width TW, the adjacent shoulder main groove 35 and the center main groove 31 in the tire width direction The distance may be too small, and the width of the second land portion 22 in the tire width direction may be too narrow. In this case, the rigidity of the second land portion 22 may be too low, and the dry steering stability, which is the steering stability when traveling on a dry road surface, may be reduced. Further, when the distance DGs from the tire equatorial plane CL to the groove width center CGs of the shoulder main groove 35 exceeds 45% of the ground contact width TW, the shoulder main groove 35 is too close to the tire width direction. The width of the side shoulder land portion 25 in the tire width direction may be too narrow. In this case, the rigidity of the shoulder main groove side shoulder land portion 25 may be too low, and the dry steering stability may be reduced.

  On the other hand, when the distance DGs from the tire equatorial plane CL to the groove width center CGs of the shoulder main groove 35 is in the range of 35% to 45% of the contact width TW, the shoulder main groove 35 is defined. The width of the land portion 20 of the second land portion 22 and the shoulder main groove side shoulder land portion 25 can be set to an appropriate size in the tire width direction, and the rigidity of the second land portion 22 and the shoulder main groove side shoulder The rigidity of the land portion 25 can be secured in a well-balanced manner. This makes it possible to more reliably ensure dry handling.

  Further, since the center main groove 31 is disposed at a position where the distance DGc from the tire equatorial plane CL to the groove width center CGc of the center main groove 31 is in the range of 10% to 20% of the contact width TW. The rigidity of the center land portion 21 and the rigidity of the second land portion 22 and the center main groove side shoulder land portion 24 can be secured in a well-balanced manner. That is, when the distance DGc from the tire equatorial plane CL to the groove width center CGc of the center main groove 31 is less than 10% of the ground contact width TW, the distance between the two center main grooves 31 becomes too small. The width of the portion 21 in the tire width direction may be too narrow. In this case, the rigidity of the center land portion 21 may be too low, and the dry steering stability, which is the steering stability when traveling on a dry road surface, may be reduced. Further, when the distance DGc from the tire equatorial plane CL to the groove width center CGc of the center main groove 31 exceeds 20% of the ground contact width TW, the center main groove 31 is too close to the tire width direction outer side, so that the second land portion There is a possibility that the width in the tire width direction of the shoulder land portion 24 and the center main groove side shoulder portion 24 may become too narrow. In this case, the rigidity of the second land portion 22 and the center main groove side shoulder land portion 24 may be too low, and the dry steering stability may be reduced.

  On the other hand, when the distance DGc from the tire equatorial plane CL to the groove width center CGc of the center main groove 31 is in the range of 10% to 20% of the ground contact width TW, the center main groove 31 is defined. The land portions 20 of the center land portion 21, the second land portion 22, and the center main groove side shoulder land portion 24 can have an appropriate width in the tire width direction, and the rigidity of the center land portion 21, The rigidity of the second land portion 22 and the center main groove side shoulder land portion 24 can be secured in a well-balanced manner. This makes it possible to more reliably ensure dry handling.

  Further, the main groove 30 including the center main groove 31 and the shoulder main groove 35 has land widths WGc and WGs of the respective main grooves 30 within the range of 5% to 9% of the ground contact width TW. The drainage property in the main groove 30 can be secured while securing the rigidity of 20. That is, when the groove widths WGc and WGs of the main groove 30 are less than 5% of the ground contact width TW, the groove widths WGc and WGs of the main groove 30 are too narrow, making it difficult to ensure drainage in the main groove 30. There is a risk that the wet handling may be reduced. When the groove width WGc, WGs of the main groove 30 exceeds 9% of the ground contact width TW, the groove width WGc, WGs of the main groove 30 is too wide, so the tire of the land portion 20 defined by the main groove 30 By reducing the width in the width direction, the rigidity of the land portion 20 may be reduced, and the dry steering stability may be reduced.

  On the other hand, when the groove widths WGc and WGs of the plurality of main grooves 30 are in the range of 5% to 9% of the ground contact width TW, the groove widths WGc and WGs of the main grooves 30 Can be secured to such an extent that the rigidity of the land portion 20 is reduced, and the drainage property of the main groove 30 can be secured. Thereby, it is possible to achieve both dry and wet operations.

  Further, since the groove area ratio of the grooves excluding the main groove 30 is in the range of 2% or more and 10% or less, the tread surface 10 has the main groove 30 while ensuring the drainage property in the grooves other than the main groove 30. The rolling resistance can be reduced by suppressing the deformation of the land portion 20 defined. That is, when the groove area ratio of the grooves excluding the main groove 30 is less than 2%, the groove area ratio is too small, so it is difficult to drain water between the tread surface 10 and the road surface by grooves other than the main groove 30. There is a risk of In addition, when the groove area ratio of the grooves excluding the main groove 30 exceeds 10%, it is difficult to secure the rigidity of the land portion 20 defined by the main groove 30, and the land portion 20 is easily deformed. May increase. On the other hand, when the groove area ratio of the grooves excluding the main groove 30 is in the range of 2% or more and 10% or less, the deformation of the land portion 20 is suppressed while securing drainage with grooves other than the main groove 30. Rolling resistance can be reduced. As a result of these, it is possible to achieve both the suppression of the deterioration of the rolling resistance and the reduction of the road noise more reliably while improving the wet handling.

  In addition, since the plain inner side sipe 51 extending in the tire width direction and in which the inner end 51a communicates with the center main groove 31 is formed between the plain portion 70 and the center main groove 31, The rigidity of the portion in the vicinity of the center main groove 31 in the center main groove side shoulder land portion 24 can be lowered. Thus, the contact pressure in the vicinity of the center main groove 31 in the second land portion 22 and the center main groove side shoulder land portion 24 can be prevented from becoming too high, and the contact pressure on the tread surface 10 can be made uniform. Can. As a result, the deterioration of the rolling resistance can be suppressed more reliably.

  In addition, since the inter-main-groove sipe 60 extending in the tire width direction and communicating with the center main groove 31 is formed in the center land portion 21 disposed between the center main grooves 31, the second land portion 22 or The rigidity of the center land portion 21 can be suppressed from becoming too high with respect to a portion near the center main groove 31 in the center main groove side shoulder land portion 24. As a result, an increase in the difference in contact pressure between the land portions 20 on both sides of the center main groove 31 can be suppressed, and the contact pressure of the tread surface 10 can be made uniform. As a result, the deterioration of the rolling resistance can be suppressed more reliably.

  Further, the plain inner side sipe 51 and the inter-main-groove sipe 60 are formed on the land portions 20 adjacent to each other via the center main groove 31 and the sipes 51, 60 communicating with the same center main groove 31 extend from each other. Since the land portions 20 are disposed at the positions where the land portions 20 are disposed, the rigidity can be equalized in the land portions 20 adjacent to each other through the center main groove 31. Thereby, equalization of the contact pressure of tread surface 10 can be attained more certainly. Further, when going from the tire equatorial plane CL side to the tire width direction outer side, the plain portion inner side sipe 51 and the inter-main groove sipe 60 inclined in the tire circumferential direction with respect to the tire width direction are respectively All the slopes in the same direction are arranged on the extension line, so the water between the tread surface 10 and the road surface is more reliable between the main groove sipe 60 and the plane portion inner sipe 51 It is possible to drain water from the tire equatorial plane CL side to the outside in the tire width direction. As a result of these, it is possible to suppress the deterioration of the rolling resistance while improving the wet steering stability more reliably.

  The center main groove side shoulder groove portion 41 and the shoulder main groove side shoulder groove portion 43 are respectively disposed between a plurality of shoulder lug grooves 46 extending in the tire width direction and the shoulder lug grooves 46 adjacent in the tire circumferential direction. Thus, the rigidity of the center main groove side shoulder land portion 24 and the shoulder main groove side shoulder land portion 25 can be made uniform in the tire circumferential direction. As a result, it is possible to suppress uneven contact pressure due to partial increase in the rigidity of the center main groove side shoulder land portion 24 and the shoulder main groove side shoulder land portion 25, which is more reliable. The contact pressure of the tread surface 10 can be made uniform. As a result, the deterioration of the rolling resistance can be more reliably suppressed.

  Moreover, since the recessed part 80 is formed in the tire width direction outer side of the earthing | grounding end T in the shoulder land part 23, a turbulent flow is generated to air by the recessed part 80 at the time of rolling of the pneumatic tire 1, and the air from the tire surface Peeling can be suppressed. Thereby, air resistance can be reduced, and as a result, deterioration of rolling resistance can be more reliably suppressed.

  Further, since the shoulder main groove 35 is formed on the inner side in the vehicle mounting direction from the center main groove 31, drainage performance can be ensured by the shoulder main groove 35 when the vehicle travels straight. Thereby, wet handling can be ensured. Further, since the shoulder main groove 35 is not formed on the tire width direction outer side of the center main groove 31 located on the tire width direction outer side, the rigidity of the center main groove side shoulder land portion 24 can be secured. It is possible to secure sex. As a result of these, it is possible to more reliably achieve both wet and dry steering.

  The tread surface 10 has a groove area ratio of the center main groove 31 and the shoulder main groove 35, that is, the groove area ratio of the main groove 30 is in the range of 20% to 35%, which is more reliable. It is possible to ensure the drainage performance of the main groove 30 while securing the rigidity of the land portion 20. That is, when the groove area ratio of the main groove 30 is less than 20%, the groove area ratio of the main groove 30 is too small, and it becomes difficult to appropriately ensure the drainage property in the main groove 30, There is a risk that it will be difficult to secure the safety. In addition, when the groove area ratio of the main groove 30 exceeds 35%, the groove area ratio of the main groove 30 is too large, so it becomes difficult to appropriately secure the rigidity of the land portion 20, resulting in dry steering stability. There is a risk that it will be difficult to secure.

  On the other hand, when the groove area ratio of the main groove 30 is in the range of 20% or more and 35% or less, the drainage property in the main groove 30 is secured while suppressing the decrease in the rigidity of the land portion 20 more reliably. Can. As a result, it is possible to more reliably achieve both dry and wet operations.

[Modification]
In the embodiment described above, the plane portions 70 are provided at two places on both sides of the tire equatorial plane CL in the tire width direction, but the plane portions 70 may be other than two places. The plane portion 70 is provided on both sides of the tire equatorial plane CL in the tire width direction, and at least a portion is positioned within a range of 22% to 38% of the ground contact width TW in the tire width direction from the tire equatorial plane CL. If it does, the number does not matter. Further, the distance in the tire width direction from the tire equatorial plane CL and the plane width WP may be different among the plurality of plane portions 70. Similarly, in the plurality of main grooves 30, the groove widths WGc and WGs may be different from each other, the distance DGc from the tire equatorial plane CL to the groove width center CGc of the center main groove 31 is different between the center main grooves 31 It may be

  In the embodiment described above, the shoulder lug grooves 46 and the shoulder sipes 47 provided as the center main groove side shoulder groove portion 41 and the shoulder main groove side shoulder groove portion 43 are alternately arranged in the tire circumferential direction. The shoulder lug grooves 46 and the shoulder sipes 47 may not be alternately disposed. In the embodiment described above, the center main groove side shoulder groove portion 41 has a position in the tire width direction of the inner end 46 a of the shoulder lug groove 46 and a position in the tire width direction of the inner end 47 a of the shoulder sipe 47 The positions are substantially the same, but the positions in the tire width direction may be different from each other.

  In the embodiment described above, the shoulder lug grooves 46 and the shoulder sipes 47 are provided as the center main groove side shoulder groove portion 41 and the shoulder main groove side shoulder groove portion 43, but the center main groove side shoulder groove portion 41 and the shoulder main The groove side shoulder groove 43 may be either the shoulder lug groove 46 or the shoulder sipe 47. Further, the center main groove side shoulder groove portion 41 may be provided with a groove other than the shoulder lug groove 46 or the shoulder sipe 47 as the center main groove side shoulder groove portion 41. For example, the center main groove side shoulder land portion 24 is formed A narrow groove extending in the tire circumferential direction may be provided as the center main groove side shoulder groove portion 41. In this case, the position in the tire width direction of the inner edge of the narrow groove extending in the tire circumferential direction in this way is the end of the plain portion 70 on the outer side in the tire width direction.

  Further, in the embodiment described above, the plain portion inner groove portion 50 is provided by the plain portion inner sipe 51 extending in the tire width direction, but grooves other than the plain portion inner sipe 51 are provided as the plain portion inner groove portion 50. May be The plain portion inner groove portion 50 extends, for example, in the tire width direction between the plain portion 70 and the center main groove 31, and a lug groove whose inner end in the tire width direction communicates with the center main groove 31 is a plain portion inner groove portion. 50 may be provided. Alternatively, both the lug groove and the plain portion inner sipe 51 may be provided as the plain portion inner groove portion 50.

[Example]
7A to 7C are charts showing the results of performance tests of pneumatic tires. Hereinafter, the performance of the pneumatic tire 1 described above is performed for the pneumatic tire of the conventional example, the pneumatic tire 1 according to the present invention, and the pneumatic tire of the comparative example to be compared with the pneumatic tire 1 according to the present invention The evaluation test of The performance evaluation test includes road noise and rolling resistance when the pneumatic tire 1 rolls, dry steering stability which is steering stability on a dry road surface, and wet steering safety which is steering stability on a wet road surface. The test about sex was done.

  The performance evaluation test was conducted by adjusting a pneumatic tire 1 of 195 / 65R15 size called JATMA-designated tire to a JATMA standard rim wheel with a rim size of 15 × 6 J and adjusting the air pressure to 250 kPa. Also, in the tests on road noise, dry steering stability and wet steering stability, the test tire was mounted on a front wheel drive test vehicle with a displacement of 1.8 L and tested by a single passenger ride. .

  The evaluation method of each test item is road noise, by the test vehicle equipped with the test tire, the road noise level when traveling at a speed of 60 km / h on the road course of the test course, by sensory evaluation of the test driver Compared. The road noise is evaluated by representing the sensory evaluation of the test driver as an index with a conventional example described later as 100, and the larger the index, the smaller the road noise and the better the road noise performance.

  Moreover, about rolling resistance, the indoor drum test machine (drum diameter: 1707 mm) was used, and the rolling resistance coefficient in the conditions of load 4.8kN and speed 80 km / hour was computed based on ISO28580. The result is indicated by an index where the reciprocal of the rolling resistance coefficient in the conventional example described later is 100. The larger the index, the lower the rolling resistance.

  In addition, with regard to dry steering safety, a test vehicle equipped with a test tire performs sensory evaluation by a test driver when traveling on a test road on a dry road surface, and the sensory evaluation is an index using a conventional example described later as 100. It evaluated by expressing. The larger the value is, the better the dry maneuverability is.

  In addition, with regard to wet steering safety, a test vehicle equipped with a test tire performs sensory evaluation by a test driver when traveling on a test course on a wet road surface, and the sensory evaluation is an index based on a conventional example described later as 100. It evaluated by expressing. The larger the value is, the better the wet maneuverability is.

  The performance evaluation test compares the pneumatic tire according to the conventional example, which is an example of the conventional pneumatic tire, and the embodiments 1 to 20, which are the pneumatic tire 1 according to the present invention, with the pneumatic tire 1 according to the present invention. It carried out about 24 types of pneumatic tires with comparative examples 1-3 which are pneumatic tires. Among these, in the conventional pneumatic tire, the total width of the plane widths WP of the plurality of plane portions 70 is less than 10% of the ground contact width TW. Further, in the pneumatic tire of Comparative Example 1, the total width of the plane widths WP of the plurality of plain portions 70 is larger than 30% of the ground contact width TW, and in the pneumatic tire of Comparative Example 2, the plain portion 70 is a tire. The rotational direction is not designated in the pneumatic tire of Comparative Example 3, which is not located in the range of 5% to 15% of the ground contact width TW in the tire width direction from the equatorial plane CL.

  On the other hand, in Examples 1 to 20 which are an example of the pneumatic tire 1 according to the present invention, the total width of the plane widths WP of all of the plurality of plane portions 70 is within the range of 10% to 30% of the ground width TW. The rotation direction is specified, and at least a part of the plain portion 70 is located in the range of 22% to 38% of the ground contact width TW in the tire width direction from the tire equatorial plane CL. Furthermore, in the pneumatic tire 1 according to Examples 1 to 20, the plane width WP [%] of the plane portion 70 with respect to the ground contact width TW, the groove area ratio [%] of the grooves excluding the main groove 30, and the main groove with respect to the ground width TW. The distance DGc [%] from the tire equatorial plane CL to the groove width center CGc of the center main groove 31 with respect to the groove width WGc and WGs [%] of 30 and the shoulder main with respect to the contact width TW Distance DGs [%] to groove width center CGs of groove 35, presence / absence of plain portion inner groove portion 50, presence / absence of sipe 60 between main grooves, presence / absence of shoulder sipe 47 between shoulder lug grooves 46, same main groove 30 It is disposed at a position where the sipes communicating with each other are on the extension line, and whether the sipe of the plurality of land portions 20 is formed in a V shape as a whole, No, whether the shoulder main groove 35 there is a specification of the vehicle mounting direction is arranged inside the vehicle mounting direction, the groove area ratio of the main groove 30 [%] is different respectively.

  As a result of conducting a performance evaluation test using these pneumatic tires 1, as shown to FIG. 7A-FIG. 7C, the pneumatic tire 1 which concerns on Examples 1-20 is compared with a prior art example and Comparative Examples 1-3. It has been found that the wet handling can be improved while suppressing the increase in rolling resistance, and furthermore, the road noise can be reduced. That is, the pneumatic tire 1 according to Examples 1 to 20 can achieve both suppression of deterioration of rolling resistance and reduction of road noise while improving wet handling.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 tread part 3 shoulder part 4 sidewall 5 bead part 6 carcass layer 7 belt layer 10 tread surface 20 land part 21 center land part 22 second land part 23 shoulder land part 24 center main groove side shoulder land part 25 Shoulder main groove side shoulder land portion 30 main groove 31 center main groove 35 shoulder main groove 41 center main groove side shoulder groove portion 43 shoulder main groove side shoulder groove portion 46 shoulder lug groove 46a, 47a, 51a inner end portion 46b, 47b, 51b outside End 47 Shoulder sipes 50 Plain section inner groove section 51 Plain section inner sipe 60 Main slot between sipes 65 Bend section 70 Plain section 80 recess

Claims (10)

A pneumatic tire mounted on a vehicle so as to rotate in a designated rotation direction about a rotation axis when the vehicle advances.
Two center main grooves formed one on each side of the tire width direction center line of the tread surface and extending in the tire circumferential direction,
One shoulder main groove formed on the tire width direction outer side of the center main groove of the tread surface;
A plurality of land portions defined by the center main groove and the shoulder main groove;
The tire is located on the tire width direction outside of the center main groove located on the opposite side of the side where the shoulder main groove is located among the two center main grooves, and the tire width direction outside of the shoulder main groove, A shoulder land portion which is the land portion defined by a main groove or the shoulder main groove;
A shoulder main groove side shoulder groove portion which is formed in the shoulder land portion defined by the shoulder main groove and extends in the tire width direction and whose inner end in the tire width direction communicates with the shoulder main groove;
A center main groove side shoulder groove portion formed on the shoulder land portion defined by the center main groove and separated from the center main groove.
It is provided between the shoulder main groove and the center main groove adjacent to the shoulder main groove, and between the center main groove defining the shoulder land portion and the center main groove side shoulder groove portion, and the tire circumference A plane portion which is an area in which a groove is not formed over the entire circumference in the direction
Equipped with
At least a portion of the plain portion is located within a range of 22% to 38% of the contact width in the tire width direction from the tire width direction center line.
In the pneumatic tire, a total width of the plurality of plain portions in the tire width direction is in a range of 10% to 30% of the contact width in the plane portion.   The pneumatic tire according to claim 1, wherein a width of the plain portion in a tire width direction is in a range of 5% to 15% of the contact width. The shoulder main groove is disposed at a position where the distance from the tire width direction center line to the groove width center of the shoulder main groove is within a range of 35% to 45% of the contact width.
The center main groove is disposed at a position where the distance from the tire width direction center line to the groove width center of the center main groove is in the range of 10% to 20% of the contact width,
The shoulder main groove and the center main groove each have a groove width within a range of 5% to 9% of the contact width,
3. The pneumatic tire according to claim 1, wherein a groove area ratio of the grooves excluding the center main groove and the shoulder main groove is in a range of 2% to 10% in the tread surface. Between the plain portion and the center main groove, a plain portion inner groove portion is formed, which extends in the tire width direction and whose inner end in the tire width direction communicates with the center main groove.
The pneumatic tire according to any one of claims 1 to 3, wherein the plain portion is provided on the outer side in the tire width direction from the position in the tire width direction of the outer end of the plain portion inner groove portion in the tire width direction.   The pneumatic according to any one of claims 1 to 4, wherein a sipe extending in the tire width direction and in communication with the main groove is formed in the land portion disposed between the center main grooves. tire. Between the plain portion and the center main groove and between the center main grooves, a sipe is formed which extends in the tire width direction and at least one end in the tire width direction communicates with the main groove,
A plurality of sipes are disposed in the tire circumferential direction,
The plurality of sipes extend in the tire width direction and incline in the tire circumferential direction with respect to the tire width direction, and when going from the tire width direction centerline side to the tire width direction outer side, the direction in the tire circumferential direction is All are inclined in the same direction,
The plurality of sipes are disposed at positions where the sipes formed in the land portions adjacent to each other via the center main groove communicate with the same center main groove are extended lines with each other. The pneumatic tire of any one of 1 to 3. The center main groove side shoulder groove portion and the shoulder main groove side shoulder groove portion are:
A plurality of shoulder lug grooves each extending in the tire width direction,
A shoulder sipe disposed between the shoulder lug grooves adjacent in the tire circumferential direction and extending in the tire width direction;
The pneumatic tire according to any one of claims 1 to 6, which has   The pneumatic tire according to any one of claims 1 to 7, wherein a recess is formed on the outer side in the tire width direction of the ground contact end in the shoulder land portion. The pneumatic tire has a designated mounting direction with respect to a vehicle,
The pneumatic tire according to any one of claims 1 to 8, wherein the shoulder main groove is formed on the inner side in the vehicle mounting direction than the center main groove.   The pneumatic tire according to any one of claims 1 to 9, wherein a groove area ratio of a total of the center main groove and the shoulder main groove in the tread surface is in a range of 20% to 35%.

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