JP2019111861A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of suppressing a difference in contact length between a first side and a second side in a tire width direction when going straight. In a pneumatic tire, a rubber surface layer portion includes a first rubber portion formed of a first rubber and a second rubber formed of a second rubber having a rubber hardness greater than that of the first rubber. A rubber part, the first rubber part is disposed on the first side in the tire width direction, the second rubber part is disposed on the second side in the tire width direction, and the first rubber part and the second rubber part Is disposed between a pair of main grooves arranged on the outermost side in the tire width direction, and the total cord mass per unit width of the belt reinforcing portion overlapping the first rubber portion in the tire radial direction is It is larger than the total cord mass per unit width of the belt reinforcing portion overlapping the rubber portion in the tire radial direction. [Selection] Figure 4

Description

  The present invention relates to a pneumatic tire.

  Conventionally, for example, a pneumatic tire is provided with a rubber surface layer having an outer surface in the tire radial direction, and the first and second sides of the rubber surface layer in the tire width direction are formed of rubber having different rubber hardness. (E.g., Patent Document 1). In such a pneumatic tire, since a difference in the contact length is generated between the first side and the second side in the tire width direction when going straight, for example, the conicity generated when going straight (force acting in the tire width direction) ) Will be larger.

JP 2012-76593 A

  Then, a subject is providing the pneumatic tire which can suppress that the difference of contact-contact length arises between the 1st side of a tire width direction, and a 2nd side at the time of going straight.

  The pneumatic tire is a pneumatic tire provided with a plurality of main grooves extending in the circumferential direction of the tire, and is disposed on the rubber surface portion having an outer surface in the radial direction of the tire and inside the tire surface in the tire radial direction A belt portion in which the cords are disposed to be inclined with respect to the tire circumferential direction, and a belt reinforcing portion disposed in the tire radial direction outside the belt portion and in which the cords are disposed along the tire circumferential direction The rubber surface layer portion includes a first rubber portion formed of a first rubber, and a second rubber portion formed of a second rubber having a rubber hardness greater than that of the first rubber. The first rubber portion is disposed on the first side in the tire width direction, and the second rubber portion is disposed on the second side in the tire width direction, and the first rubber portion and the second rubber portion The interface is defined by the pair of main The cord total mass per unit width of the belt reinforcing portion disposed between and overlapping the first rubber portion in the tire radial direction is the unit width of the belt reinforcing portion overlapping the second rubber portion in the tire radial direction Greater than the per-cord total mass.

  Further, in the pneumatic tire, the first rubber portion includes a first ground contact region from the ground end on the first side in the tire width direction to the interface, and the second rubber portion is a second tire in the tire width direction. The total cord mass per unit width of the belt reinforcing portion including the second ground contact region from the ground contact end on the side to the interface and overlapping the first ground contact region in the tire radial direction corresponds to the second ground region and the tire diameter It may be configured to be larger than the total cord mass per unit width of the belt reinforcing portions overlapping in the direction.

  In the pneumatic tire, a first shoulder land portion divided by a main groove disposed on the first side in the tire width direction and a ground contact end, and a main groove disposed on the second side in the tire width direction And a second shoulder land portion separated by the ground contact end, and a cord total mass per unit width of the belt reinforcing portion overlapping the first shoulder land portion in the tire radial direction is the second shoulder land portion. It may be configured to be larger than the total cord mass per unit width of the belt reinforcing portion overlapping the portion in the tire radial direction.

  Further, in the pneumatic tire, the belt reinforcing portion includes an edge reinforcing layer overlapping in the tire radial direction with an end portion of the belt portion in the tire width direction, and the edge reinforcing layer is disposed on the outermost side in the tire width direction. It may be arranged on the outer side in the tire width direction than the main groove to be cut.

  Further, in the pneumatic tire, the second rubber portion may be disposed outside when the vehicle is mounted.

  In addition, the pneumatic tire includes a plurality of land portions defined by the plurality of main grooves and the ground contact end, and the void ratio of the land portion formed of the first rubber portion is formed of the second rubber portion. The configuration may be smaller than the void ratio of the land portion to be cut.

  In addition, the pneumatic tire may include a center land portion including a tire equatorial plane by being divided by the plurality of main grooves, and the interface may be located at the center land portion.

FIG. 1 is a cross-sectional view of an essential part of a tire meridional surface of a pneumatic tire according to an embodiment. FIG. 2 is a development view of a tread surface of the pneumatic tire according to the embodiment. FIG. 3 is an enlarged view of a III region of FIG. FIG. 4 is an enlarged view of a region IV of FIG. 1 and showing the position of the belt reinforcing portion. FIG. 5 is an enlarged view of a region V of FIG. 1 and showing a position of a belt reinforcing portion. FIG. 6 is a schematic cross-sectional view of a tire meridional surface of a belt reinforcing portion according to the embodiment. FIG. 7 is a view showing a contact shape of a pneumatic tire according to a comparative example. FIG. 8 is a view showing a contact shape of the pneumatic tire according to FIGS. 1 to 6. FIG. 9 is a schematic cross-sectional view in a tire meridional plane of a belt reinforcing portion according to another embodiment. FIG. 10 is a schematic cross-sectional view in a tire meridional plane of a belt reinforcing portion according to still another embodiment.

  Hereinafter, one embodiment of a pneumatic tire will be described with reference to FIGS. 1 to 8. In each of the drawings (the same applies to FIG. 9 and the subsequent figures), the dimensional ratio of the drawings and the actual dimensional ratio do not always match, and the dimensional ratio between the respective drawings does not necessarily match.

  In each figure, the first direction D1 is the tire width direction D1 parallel to the tire rotation axis which is the rotation center of the pneumatic tire (hereinafter, also simply referred to as "tire") 1, and the second direction D2 is The tire radial direction D2 is a diameter direction of the tire 1, and the third direction D3 is the tire circumferential direction D3 around the tire rotation axis. In the tire width direction D1, the first side D11 is also referred to as a first width direction side D11, and the second side D12 is also referred to as a second width direction side D12.

  The tire equatorial plane S1 is a plane perpendicular to the tire rotation axis and located at the center of the tire 1 in the tire width direction D1. The tire meridional plane is a plane including the tire rotation axis and the tire equatorial plane It is a plane orthogonal to the plane S1. The tire equator line is a line at which the outer surface of the tire 1 in the tire radial direction D2 (a tread surface 2a described later) intersects with the tire equator surface S1.

  As shown in FIG. 1, the tire 1 according to the present embodiment includes a pair of bead portions 11 having beads, sidewall portions 12 extending from the bead portions 11 to the outside in the tire radial direction D2, and a pair of sidewall portions The tread portion 2 is connected to the outer end portions of the twelve tire radial directions D2, and the outer surface of the tire radial direction D2 is in contact with the road surface. In the present embodiment, the tire 1 is a pneumatic tire 1 having air introduced therein, and is mounted on a rim 20.

  In addition, the tire 1 is provided with a carcass layer 13 bridged between a pair of beads, an inner liner layer 14 which is disposed inside the carcass layer 13 and is excellent in the function of blocking gas permeation in order to maintain air pressure. Is equipped. The carcass layer 13 and the inner liner layer 14 are disposed along the tire inner circumference across the bead portion 11, the sidewall portion 12, and the tread portion 2.

  The tread portion 2 includes a tread rubber 3 having a tread surface 2 a that is in contact with a road surface, and a belt portion 4 disposed between the tread rubber 3 and the carcass layer 13. The tread portion 2 further includes a belt reinforcing portion 5 disposed between the tread rubber 3 and the belt portion 4 in order to reinforce the belt portion 4.

  The tread surface 2a has a contact surface that actually contacts the road surface, and among the contact surfaces, the outer ends in the tire width direction D1 are referred to as contact ends 2b and 2c. The tread surface 2a has the tire 1 mounted on a regular rim 20 and is filled with a regular internal pressure. The tire 1 is placed vertically on a flat road surface, and the tread surface 2a is in contact with the road surface when a regular load is applied. Point to Further, of the ground ends 2b and 2c, the ground end 2b on the first widthwise side D11 is referred to as a first ground end 2b, and the ground end 2c on the second widthwise side D12 is referred to as a second ground end 2c.

  In the standard system including the standard on which the tire 1 is based, the regular rim 20 is the rim 20 which is defined for each tire 1 in the standard, for example, if it is JATMA, it is a standard rim, if it is TRA, "Design Rim", ETRTO If it is "Measuring Rim".

  The normal internal pressure is the air pressure specified in each tire 1 in the standard system including the standard on which the tire 1 is based, the maximum air pressure in the case of JATMA, the table in the case of TRA, "TIRE LOAD LIMITS AT VARIOUS COLD The maximum value described in “INFLATION PRESSURES” is “INFLATION PRESSURE” in the case of ETRTO, but is 180 kPa when the tire 1 is for a passenger car.

  The normal load is a load defined in each tire 1 in the standard system including the standard on which the tire 1 is based, the maximum load capacity in the case of JATMA, and the maximum in the above table in the case of TRA. If the value is ETRTO, it is "LOAD CAPACITY", but if the tire 1 is for a passenger car, it is 85% of the corresponding load of internal pressure 180 kPa.

  The belt portion 4 includes at least one (two in the present embodiment) belt layers 41 and 42. Specifically, the belt portion 4 includes a first belt layer 41 and a second belt layer 42 disposed outside the first belt layer 41 in the tire radial direction D2. Each of the belt layers 41 and 42 includes a plurality of cords (also referred to as “belt cords”) arranged in parallel and a topping rubber that covers the cords. The number of layers of the belt layers 41 and 42 is not particularly limited.

  The cords of the belt layers 41 and 42 are arranged in parallel in the tire width direction D1 so as to intersect at a predetermined inclination angle (for example, 5 ° or more, preferably 15 ° to 35 °) with respect to the tire circumferential direction D3. ing. The cords of the first and second belt layers 41 and 42 are inclined in opposite directions with respect to the tire circumferential direction D3 and arranged so as to cross each other. The material of the cord is not particularly limited, but, for example, organic fibers such as polyester, rayon, nylon, or aramid, and metals such as steel are suitably used.

  As shown in FIGS. 1 and 2, the tread rubber 3 includes a plurality of main grooves 3 a and 3 b extending in the tire circumferential direction D3. The main grooves 3a, 3b extend continuously in the tire circumferential direction D3. In the present embodiment, the main grooves 3a and 3b extend in a straight shape along the tire circumferential direction D3. However, the present invention is not limited to such a configuration. For example, refraction is repeated to extend in a zigzag shape , Or, for example, may be configured to extend in a wave shape by repeating bending.

  The main grooves 3a, 3b are provided with a portion where the grooves are shallow, so-called tread wear indicator (not shown), for example, so that the degree of wear can be known by exposing as the wear. Further, for example, the main grooves 3a and 3b have a groove width of 3% or more of the distance between the ground contact ends 2b and 2c (the dimension in the tire width direction D1). Also, for example, the main grooves 3a and 3b have a groove width of 5 mm or more.

  In the plurality of main grooves 3a, 3b, the pair of main grooves 3a, 3a arranged on the outermost side in the tire width direction D1 is called shoulder main groove 3a, and is arranged between the pair of shoulder main grooves 3a, 3a The main groove 3b to be formed is called a center main groove 3b. In the present embodiment, although the number of the center main grooves 3b is two, it is not limited to such a configuration, and may be one or three or more, for example.

  The tread rubber 3 includes a plurality of land portions 3c to 3g divided by the main grooves 3a and 3b and the ground contact ends 2b and 2c. In the plurality of land portions 3c to 3g, land portions 3c and 3d divided by the shoulder main groove 3a and the ground contact ends 2b and 2c are called shoulder land portions 3c and 3d, and adjacent main grooves 3a and 3b The land portions 3e to 3g which are divided by the pair and disposed between the pair of shoulder land portions 3c and 3d are referred to as middle land portions 3e to 3g.

  The shoulder land portion 3c on the first widthwise side D11 is referred to as a first shoulder land portion 3c, and the shoulder land portion 3d on the second widthwise side D12 is referred to as a second shoulder land portion 3d. Of the middle land portions 3e to 3g, land portions 3e and 3f divided by the shoulder main groove 3a and the center main groove 3b are referred to as mediate land portions 3e and 3f, and are formed by the center main grooves 3b and 3b. The land section 3g to be divided is called center land section 3g.

  In the present embodiment, the center main grooves 3b, 3b are arranged to sandwich the tire equatorial plane S1. Thereby, center land part 3g is arranged so that tire equatorial plane S1 may be included.

  The outer ends 2d and 2e of the tread rubber 3 in the tire width direction D1 of the tread surface 2a are referred to as tread outer ends 2d and 2e. The tread outer end 2d of the first widthwise side D11 is referred to as the first tread outer end 2d, and the tread outer end 2e of the second widthwise side D12 is referred to as the second tread outer end 2e.

  Furthermore, the inner ends 2f and 2g in the tire width direction D1 of the shoulder lands 3c and 3d in the tread surface 2a are referred to as shoulder land inner ends 2f and 2g. The shoulder land portion inner ends 2f and 2g are also the outer ends of the shoulder main groove 3a in the tire width direction D1, and thus are also referred to as shoulder main groove outer ends 2f and 2g.

  In addition, the land portions 3c to 3g are provided with a plurality of land grooves 3h and 3i. The plurality of land grooves 3h and 3i extend so as to intersect with the tire circumferential direction D3. And, among land grooves 3h and 3i extending to intersect tire circumferential direction D3, land groove 3h having a groove width of 1.6 mm or more is called width groove 3h, and the groove width is less than 1.6 mm. One land ditch 3i is called sipe 3i. Land portions 3c to 3g may be provided with land grooves having a groove width smaller than the groove width of main grooves 3a and 3b and extending continuously or intermittently along tire circumferential direction D3. The grooves are called circumferential grooves.

  The tire 1 has a structure that is asymmetric with respect to the tire equatorial plane S1. In the present embodiment, the tire 1 is a tire whose mounting direction to a vehicle is specified, and when mounted on the rim 20, it is a tire whose left or right of the tire 1 is specified to face the vehicle. The tread pattern formed on the tread surface 2 a of the tread portion 2 has a shape that is asymmetric with respect to the tire equatorial plane S1.

  The direction of attachment to the vehicle is displayed on the sidewall 12. Specifically, the sidewall portion 12 is provided with sidewall rubber 12a disposed on the outer side in the tire width direction D1 of the carcass layer 13 so as to constitute the outer surface of the tire, and the surface of the sidewall rubber 12a is displayed Have a department.

  For example, when the vehicle is mounted, one sidewall portion 12 disposed on the inner side (the left side in each drawing, hereinafter also referred to as "the inner side of the vehicle") is an indication to be the inner side of the vehicle (for example, "INSIDE" ) Is attached. Also, for example, when the vehicle is mounted, the other sidewall portion 12 disposed on the outer side (right side in each drawing, hereinafter also referred to as “vehicle outer side”) is an indication that it is the vehicle outer side (for example, “OUTSIDE Etc.) is attached. In the present embodiment, the first widthwise side D11 is an inner side of the vehicle, and the second widthwise side D12 is an outer side of the vehicle.

  As shown in FIG. 3, the tread rubber 3 has a rubber surface layer portion 6 having a tread surface 2 a which is an outer surface in the tire radial direction D 2 and a rubber inner layer disposed on the inner side of the rubber surface portion 6 in the tire radial direction D 2. And 7 are provided. In addition, not only the structure that it is one layer, but the structure of being two or more layers may be sufficient as the rubber | gum inner-layer part 7. FIG. Further, in the rubber inner layer portion 7, the rubber inner layer portion 7 disposed at the innermost in the tire radial direction D2 is referred to as a base rubber, and the rubber surface layer portion 6 and the other rubber inner layer portions 7 are referred to as a cap rubber.

  The rubber surface layer portion 6 includes a first rubber portion 6a formed of a first rubber, and a second rubber portion 6b formed of a second rubber having a rubber hardness greater than that of the first rubber. . The rubber hardness is a hardness measured at 23 ° C. based on “JIS K6253-1-2012 3.2 durometer hardness”.

  Although the rubber hardness of each rubber is not particularly limited, for example, the rubber hardness of the first rubber may be 66 to 70, and the rubber hardness of the second rubber may be 70 to 74, for example. Also, for example, the rubber hardness difference between the first rubber and the second rubber is not particularly limited, but may be 2 to 6, for example.

  The rubber surface layer portion 6 includes an interface 6c between the first rubber portion 6a and the second rubber portion 6b. The interface 6c is disposed between the pair of shoulder main grooves 3a and 3a. As a result, distortion occurs at the interface 6c disposed between the pair of shoulder main grooves 3a, 3a at the time of braking, so the distortion becomes a resistance to the road surface. Therefore, since the braking distance can be reduced, the braking performance can be improved.

  Further, in the present embodiment, the interface 6c is located not on the main grooves 3a and 3b but on the land portion 3g so as to appear on the tread surface 2a. Thereby, distortion generated at the interface 6c becomes a direct resistance to the road surface.

  Moreover, in the present embodiment, the interface 6c is located on the center land portion 3g, specifically, on the tire equatorial plane S1. Thereby, the interface 6c is closest to the tire equatorial plane S1 (specifically, includes the tire equatorial plane S1) while the interface land 6c is closest to the tire equatorial plane S1 as the contact pressure at the time of braking increases. It will be located at 3g. As a result, the distortion generated at the interface 6c becomes an effective resistance to the road surface, so that the braking distance can be effectively reduced.

  The interface 6c may be, for example, positioned in the main grooves 3a and 3b and may not appear in the tread surface 2a. The interface 6c may be located at the middle land portions 3e to 3g, but may be located at the media land portions 3e and 3f.

  The interface 6c may be located at the center land portion 3g, but may be located away from the tire equatorial plane S1. For example, the distance between the interface 6c and the tire equatorial plane S1 is preferably 10% or less of the distance between the ground contact ends 2b and 2c (the dimension in the tire width direction D1), and is 5% or less Is more preferable, and 3% or less is very preferable.

  Moreover, in the present embodiment, the first rubber portion 6a is disposed on the first widthwise side D11, and the second rubber portion 6b is disposed on the second widthwise side D12. That is, the first rubber portion 6a is disposed inside the vehicle, and the second rubber portion 6b is disposed outside the vehicle. As a result, the second rubber portion 6b having a relatively large rubber hardness is disposed on the vehicle outer side where the ground contact area increases when turning. Therefore, since the rigidity on the outside of the vehicle can be increased, steering stability performance at the time of turning can be improved.

  Returning to FIG. 2, in the present embodiment, the void ratio of the land portions 3c, 3e, 3g formed by the first rubber portion 6a is the void ratio of the land portions 3d, 3f, 3g formed by the second rubber portion 6b. It is smaller than the ratio. Thus, the void ratio of land portions 3c, 3e, 3g formed of the first rubber portion 6a having a relatively small rubber hardness is the land portion 3d formed of the second rubber portion 6b having a relatively large rubber hardness. , 3f and 3g are smaller than the void ratio. Accordingly, it is possible to suppress an increase in the difference in rigidity between the land portions 3c, 3e, 3g on the first widthwise side D11 and the land portions 3d, 3f, 3g on the second widthwise side D12.

  Land portions 3c, 3e, 3g formed of the first rubber portion 6a are the first width direction of the shoulder land portion 3c and the median land portion 3e on the first width direction D11, and the center land portion 3g. It is an area of the side D11. Therefore, the void ratio of the land portions 3c, 3e, 3g formed by the first rubber portion 6a is equal to the area of the land portions 3c, 3e, 3g between the first ground end 2b and the interface 6c (main groove 3a, It is the ratio of the sum of the areas of land grooves 3h and 3i to the sum of land grooves 3h and 3i) not including 3b.

  Further, land portions 3d, 3f, 3g formed of the second rubber portion 6b are the second width direction of the shoulder land portion 3d and the median land portion 3f on the second width direction D12 and the center land portion 3g. It is an area of the side D12. Therefore, the void ratio of the land portions 3d, 3f, 3g formed of the second rubber portion 6b is equal to the area of the land portions 3d, 3f, 3g between the second ground end 2c and the interface 6c (main groove 3a, It is the ratio of the sum of the areas of land grooves 3h and 3i to the sum of land grooves 3h and 3i) not including 3b.

  The pitch of the width grooves 3h (interval in the tire circumferential direction D3) in the median land portion 3e on the first width direction D11 is the pitch of the width grooves 3h in the median land portion 3f on the second width direction D12. It's getting bigger than that. The pitch of the width grooves 3h (except for the sipe 3i) in the shoulder land portion 3c on the first width direction D11 is larger than the pitch of the width grooves 3h in the shoulder land 3d on the second width direction D12. It has become.

  Here, the configuration of the belt reinforcing portion 5 will be described with reference to FIGS. 3 to 6. In FIG. 4 and FIG. 5, the belt reinforcing portion 5 is hatched and illustrated, and the belt portion 4 is illustrated by a broken line.

  As shown in FIGS. 3 to 5, the belt reinforcing portion 5 includes a cap reinforcing layer 51 disposed so as to cover the belt layers 41 and 42 in the tire width direction D1. Further, the belt reinforcing portion 5 is provided with a first edge reinforcing layer 52 disposed to cover an end of the first widthwise side D11 of the belt layers 41 and 42, and a second widthwise side D12 of the belt layers 41 and 42. And a second edge reinforcing layer 53 disposed to cover the end of the second.

  The first edge reinforcing layer 52 is disposed on the outer side in the tire radial direction D2 than the cap reinforcing layer 51, and the second edge reinforcing layer 53 is disposed on the inner side in the tire radial direction D2 than the cap reinforcing layer 51. It is done. The respective edge reinforcing layers 52 and 53 may be disposed inside the tire radial direction D2 with respect to the cap reinforcing layer 51, or may be disposed outside the tire radial direction D2.

  In addition, the first end (outer end of tire width direction D1) 52a of the first edge reinforcing layer 52 on the first width direction D11 is the first end 51a of the first width direction D11 of the cap reinforcing layer 51. And the second end (the outer end of the tire width direction D1) 53b of the second edge reinforcing layer 53 on the second width direction D12 is the second end of the second width direction D12 of the cap reinforcing layer 51. It is connected with 2 end 51b. The cap reinforcing layer 51 and the edge reinforcing layers 52 and 53 may not be connected to each other but may be separated.

  The end portions 51a and 51b of the cap reinforcing layer 51 are located outside the tread outer ends 2d and 2e, respectively, in the tire width direction D1. Specifically, the first end 51a of the cap reinforcing layer 51 is located on the first widthwise side D11 relative to the first tread outer end 2d, and the second end 51b of the cap reinforcing layer 51 is The second tread outer side 2e is located on the second widthwise side D12.

  The outer ends 52a and 53b of the edge reinforcing layers 52 and 53 are located outside the tread outer ends 2d and 2e, respectively, in the tire width direction D1. Specifically, the first end 52a of the first edge reinforcing layer 52 is located on the first widthwise side D11 relative to the first tread outer end 2d, and the second end of the second edge reinforcing layer 53 The portion 53b is located on the second widthwise side D12 with respect to the second tread outer end 2e.

  The inner end portions 52b and 53a of the edge reinforcing layers 52 and 53 are located on the outer side in the tire width direction D1 than the shoulder land portion inner ends 2f and 2g, respectively. Specifically, the second end 52b of the second widthwise side D12 of the first edge reinforcing layer 52 is positioned closer to the first widthwise side D11 than the first shoulder land portion inner end 2f, The first end 53a of the first widthwise side D11 of the edge reinforcing layer 53 is located on the second widthwise side D12 with respect to the second shoulder land portion inner end 2g.

  That is, the inner end portions 52b and 53a of the edge reinforcing layers 52 and 53 are located on the outer side in the tire width direction D1 than the shoulder main groove outer ends 2f and 2g, respectively. Thus, the edge reinforcing layers 52 and 53 are disposed outside the shoulder main groove 3a on the outer side in the tire width direction D1.

  Therefore, the edge reinforcing layers 52, 53 are prevented from overlapping the shoulder main groove 3a in the tire radial direction D2. As a result, it is possible to suppress the belt reinforcing portion 5 from being positioned too close to the bottom of the shoulder main groove 3a, so that it is possible to suppress, for example, the occurrence of cracks from the bottom of the shoulder main groove 3a.

  Further, as shown in FIG. 6, the belt reinforcing portion 5 includes a cord (also referred to as “reinforcement cord”) 5 a and a topping rubber 5 b that covers the cord 5 a. Although the material of the cord 5a is not particularly limited, for example, organic fibers such as polyester, rayon, nylon, or aramid are preferably used.

  The belt reinforcing portion 5 is formed by spirally winding at least one cord 5a covered with the topping rubber 5b along the tire circumferential direction D3. Thus, the cords 5a of the reinforcing layers 51 to 53 of the belt reinforcing portion 5 extend along the tire circumferential direction D3 (for example, the inclination angle is less than 5 °, preferably 3 ° or less with respect to the tire circumferential direction D3). They are arranged in parallel in the tire width direction D1 so as to intersect or in parallel with the tire circumferential direction D3.

  In the present embodiment, the number of ends of each of the reinforcing layers 51 to 53 of the belt reinforcing portion 5 is constant (not only the same but substantially the same) in the tire width direction D1. The number of ends refers to the number of cords 5 a per unit width of the reinforcing layers 51 to 53 of the belt reinforcing portion 5.

  Further, in the present embodiment, the material of the cord 5a of each of the reinforcing layers 51 to 53 is the same, and the diameter of the cord 5a of each of the reinforcing layers 51 to 53 is constant (not only the same but including substantially the same). It is. Thereby, in the present embodiment, the total mass of the cords 5a per unit width of each of the reinforcing layers 51 to 53 is constant (not only the same but including substantially the same).

  Here, the total cord mass per unit width in each region will be described. First, the first rubber portion 6a (the region from the interface 6c to the first tread outer end 2d) and the second rubber portion 6b (the region from the interface 6c to the second tread outer end 2e) are compared.

  The cap reinforcing layer 51 is disposed over the entire area of the first rubber portion 6 a and the entire area of the second rubber portion 6 b. Therefore, the ratio (W1b / W1a, W2b / W2a) of the width dimension W1b, W2b of the cap reinforcing layer 51 in which each rubber portion 6a, 6b overlaps in the tire radial direction D2 to the width dimension W1a, W2a of each rubber portion 6a, 6b Is the same.

  On the other hand, the ratio (W1c / W1a) of the width dimension W1c of the first edge reinforcing layer 52 where the first rubber portion 6a overlaps in the tire radial direction D2 with respect to the width dimension W1a of the first rubber portion 6a is the same as that of the second rubber portion 6b. The ratio (W2c / W2a) of the width dimension W2c of the second edge reinforcing layer 53 in which the second rubber portion 6b overlaps in the tire radial direction D2 with respect to the width dimension W2a is larger.

  Therefore, the cord total mass M1a per unit width of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 is the unit width of the belt reinforcing portion 5 overlapping the second rubber portion 6b in the tire radial direction D2. It is larger than the per-cord total mass M2a. Specifically, the relationship of the following equation is obtained.

M1a> M2a
M1a = (W1b + W1c) × M5 / W1a
M2a = (W2b + W2c) × M5 / W2a
W1b / W1a = W2b / W2a
W1c / W1a> W2c / W2a
Here, M5 is a total mass of the cord 5a per unit width of each of the reinforcing layers 51 to 53.

  In the belt reinforcing portion 5, the first rubber portion 6a and the belt reinforcing portion 5 overlapping in the tire radial direction D2 are positioned in the region from the interface 6c to the first tread outer end 2d in the tire width direction D1. Point to the Further, the belt reinforcing portion 5 overlapping the second rubber portion 6b in the tire radial direction D2 is located in the region from the interface 6c to the second tread outer end 2e in the tire width direction D1 of the belt reinforcing portion 5 Refers to the part that

  Next, in the first rubber portion 6a, the first ground region 6d (region from the interface 6c to the first ground end 2b) to be grounded and the second ground region 6e (interface to be grounded) in the second rubber portion 6b 6c to the second ground terminal 2c)).

  The cap reinforcing layer 51 is disposed over the entire area of the first ground area 6d and the entire area of the second ground area 6e. Therefore, the ratio (W1e / W1d, W2e / W2d) of the width dimensions W1e, W2e of the cap reinforcing layer 51 in which the grounding regions 6d, 6e overlap in the tire radial direction D2 with respect to the width dimensions W1d, W2d of the grounding regions 6d, 6e is It is the same.

  On the other hand, the ratio (W1f / W1d) of the width dimension W1f of the first edge reinforcing layer 52 in which the first ground region 6d overlaps in the tire radial direction D2 with respect to the width dimension W1d of the first ground region 6d is equal to that of the second ground region 6e. The ratio (W2f / W2d) of the width dimension W2f of the second edge reinforcing layer 53 in which the second contact region 6e overlaps in the tire radial direction D2 with respect to the width dimension W2d is larger.

  Therefore, the cord total mass M1d per unit width of the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the first ground contact region 6d is the unit width of the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the second ground region 6e. It is larger than the per-cord total mass M2d. Specifically, the relationship of the following equation is obtained.

M1d> M2d
M1d = (W1e + W1f) × M5 / W1d
M2d = (W2e + W2f) × M5 / W2d
W1e / W1d = W2e / W2d
W1f / W1d> W2f / W2d

  In the belt reinforcing portion 5, the first ground contact region 6d and the belt reinforcing portion 5 overlapping in the tire radial direction D2 are located in the region from the interface 6c to the first ground end 2b in the tire width direction D1. Point to the part. Further, the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the second ground contact region 6e is located in the region from the interface 6c to the second ground end 2c in the tire width direction D1 of the belt reinforcing portion 5 It refers to the part.

  Next, the first shoulder land portion 3c formed by the first rubber portion 6a (the area from the first shoulder land portion inner end 2f to the first ground end 2b) and the second shoulder formed by the second rubber portion 6b The land portion 3d (the area from the second shoulder land portion inner end 2g to the second ground end 2c) is compared.

  The cap reinforcing layer 51 is disposed over the entire area of the first shoulder land portion 3c and the entire area of the second shoulder land portion 3d. Therefore, the ratio (W1h / W1g, W2h /) of the width dimension W1h, W2h of the cap reinforcing layer 51 where the shoulder land portions 3c, 3d overlap in the tire radial direction D2 with respect to the width dimensions W1g, W2g of the shoulder land portions 3c, 3d W2g)) is the same.

  On the other hand, the ratio (W1i / W1g) of the width dimension W1i of the first edge reinforcing layer 52 where the first shoulder land portion 3c overlaps in the tire radial direction D2 to the width dimension W1g of the first shoulder land portion 3c is the second shoulder land The ratio (W2i / W2g) of the width dimension W2i of the second edge reinforcing layer 53 in which the second shoulder land portion 3d overlaps in the tire radial direction D2 with respect to the width dimension W2g of the portion 3d is larger.

  Therefore, the cord total mass M1g per unit width of the belt reinforcing portion 5 in which the first shoulder land portion 3c overlaps in the tire radial direction D2 is the belt reinforcement portion 5 in which the second shoulder land portion 3d overlaps in the tire radial direction D2, It is larger than the cord total mass M2g per unit width. Specifically, the relationship of the following equation is obtained.

M1g> M2g
M1g = (W1h + W1i) × M5 / W1g
M2g = (W2h + W2i) x M5 / W2g
W1h / W1g = W2h / W2g
W1i / W1g> W2i / W2g

  The belt reinforcing portion 5 in which the first shoulder land portion 3c overlaps in the tire radial direction D2 is a portion of the belt reinforcing portion 5 from the first shoulder land portion inner end 2f to the first ground end 2b in the tire width direction D1. Point to the part located in the area. Further, the belt reinforcing portion 5 in which the second shoulder land portion 3d overlaps in the tire radial direction D2 is a portion from the second shoulder land portion inner end 2g to the second ground contact end 2c in the tire width direction D1 of the belt reinforcing portion 5. It refers to the part located in the area.

  The configuration of the pneumatic tire 1 according to the present embodiment is as described above, and next, the operation of the pneumatic tire 1 according to the present embodiment will be described.

  For example, FIG. 7 shows a contact shape of a tire according to a comparative example (land grooves 3h and 3i are not shown in FIG. 7 (the same applies to FIG. 8)). In the tire according to the comparative example, the cord total mass M1a per unit width of the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the first rubber portion 6a is the first in comparison with the tire 1 according to the present embodiment. It is a tire changed to the composition that it is the same as cord gross mass M2a per unit width of belt reinforcement part 5 which overlaps with 2 rubber parts 6b in tire radial direction D2.

  And in the tire concerning a comparative example, since the 1st rubber part 6a whose rubber hardness is relatively small on the 1st width direction side D11 is arranged, the grounding length on the 1st width direction D11 (grounding shape The length in the tire circumferential direction D3 is longer than the contact length on the second widthwise side D12. Thereby, since the difference between the ground contact length on the first width direction D11 and the ground contact length on the second width direction D12 is large, for example, the conicity (force acting toward the first width direction D11) generated when going straight is growing.

  On the other hand, in the tire 1 according to the present embodiment, the cord total mass M1a per unit width of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 is the tire diameter with the second rubber portion 6b. The total cord mass M2a per unit width of the belt reinforcing portion 5 overlapping in the direction D2 is larger (see FIGS. 4 to 6). Thus, the belt reinforcing portion 5 reinforces the first rubber portion 6a more strongly than the second rubber portion 6b.

  Therefore, it can suppress that a difference arises in the rigidity of the field of the 1st rubber part 6a, and the field of the 2nd rubber part 6b. As a result, in the tire 1 according to the present embodiment, as shown in FIG. 8, it is possible to suppress the difference between the contact length on the first width direction D11 and the contact length on the second width direction D12. is made of. Therefore, it is possible to suppress an increase in the conicity generated when traveling straight.

  By the way, the contact areas 6d and 6e of the rubber portions 6a and 6b greatly contribute to the contact shape. On the other hand, the cord total mass M1d per unit width of the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the first ground contact region 6d is the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the second ground region 6e It is larger than the total cord mass M2d per unit width.

  Thus, the belt reinforcing portion 5 reinforces the first contact area 6d more strongly than the second contact area 6e. Therefore, it is possible to suppress an increase in the difference in rigidity between the first ground region 6d and the second ground region 6e, so that the ground length on the first widthwise side D11 and the ground on the second widthwise side D12 It is possible to effectively suppress the occurrence of a difference with the length.

  Further, the difference in contact length between the first shoulder land portion 3c and the second shoulder land portion 3d tends to be large due to the difference between the rubber hardness of the first rubber portion 6a and the rubber hardness of the second rubber portion 6b. On the other hand, the cord total mass M1g per unit width of the belt reinforcing portion 5 overlapping the first shoulder land portion 3c in the tire radial direction D2 is the belt reinforcing portion 5 overlapping the second shoulder land portion 3d in the tire radial direction D2. Is larger than the total cord mass M2g per unit width.

  Thus, the belt reinforcing portion 5 reinforces the first shoulder land portion 3c more strongly than the second shoulder land portion 3d. Therefore, it is possible to suppress an increase in the difference in rigidity between the first shoulder land portion 3c and the second shoulder land portion 3d, so the ground contact length on the first width direction D11 and the second width direction D12 can be suppressed. It is possible to effectively suppress the occurrence of a difference with the contact length of

  From the above, the pneumatic tire 1 according to the present embodiment is the pneumatic tire 1 including the plurality of main grooves 3a and 3b extending in the tire circumferential direction D3, and the rubber surface layer portion 6 having the outer surface in the tire radial direction D2. And a belt portion 4 disposed on the inner side in the tire radial direction D2 than the rubber surface layer portion 6 and in which the cord is disposed to be inclined with respect to the tire circumferential direction D3, and in the tire radial direction D2 relative to the belt portion 4 And a belt reinforcing portion 5 disposed on the outer side, the cord 5a being disposed along the tire circumferential direction D3, and the rubber surface layer portion 6 includes a first rubber portion 6a formed of a first rubber, and the first rubber portion 6a. And a second rubber portion 6b formed of a second rubber having a rubber hardness greater than that of 1 rubber, and the first rubber portion 6a is disposed on the first side D11 in the tire width direction D1. The second rubber portion 6b is in the tire width direction The interface 6c of the first rubber portion 6a and the second rubber portion 6b, which is disposed on the second side D12 of D1, is disposed between the pair of main grooves 3a and 3a disposed on the outermost side in the tire width direction D1. The cord total mass M1a per unit width of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 is the belt reinforcing portion 5 overlapping the second rubber portion 6b in the tire radial direction D2. Is larger than the total cord mass M2a per unit width.

  According to such a configuration, distortion occurs at the interface 6c between the first rubber portion 6a and the second rubber portion 6b at the time of braking. And since the interface 6c is disposed between the pair of main grooves 3a, 3a disposed at the outermost side in the tire width direction D1, the distortion becomes a resistance to the road surface. Therefore, since the braking distance can be reduced, the braking performance can be improved.

  Then, while the rubber hardness of the first rubber portion 6a is smaller than that of the second rubber portion 6b, the unit width per unit width of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 is The cord total mass M1a is larger than the cord total mass M2a per unit width of the belt reinforcing portion 5 overlapping the second rubber portion 6b in the tire radial direction D2.

  Thereby, it can suppress that a difference arises in the rigidity of the field of the 1st rubber part 6a, and the field of the 2nd rubber part 6b. Therefore, it is possible to suppress a difference in contact length between the first side D11 and the second side D12 in the tire width direction D1 when going straight.

  Moreover, in the pneumatic tire 1 according to the present embodiment, the first rubber portion 6a includes the first ground region 6d from the ground end 2b of the first side D11 in the tire width direction D1 to the interface 6c. The second rubber portion 6b includes a second ground area 6e from the ground end 2c of the second side D12 in the tire width direction D1 to the interface 6c, and the belt reinforcement overlapping the first ground area 6d in the tire radial direction D2. The cord total mass M1d per unit width of the portion 5 is larger than the cord total mass M2d per unit width of the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the second ground contact area 6e. is there.

  According to such a configuration, the total cord mass M1d per unit width of the belt reinforcing portion 5 overlapping in the tire radial direction D2 with the first ground contact region 6d overlaps with the second grounding region 6e in the tire radial direction D2 Since the total cord mass M2d per unit width is larger than 5, it is possible to suppress an increase in the difference in rigidity between the first ground region 6d and the second ground region 6e.

  Moreover, in the pneumatic tire 1 according to the present embodiment, the first shoulder land portion 3c divided by the main groove 3a and the ground contact end 2b disposed on the first side D11 in the tire width direction D1 and the tire width A second shoulder land portion 3d divided by the main groove 3a disposed on the most second side D12 in the direction D1 and the ground contact end 2c, and overlapping the first shoulder land portion 3c in the tire radial direction D2; The cord total mass M1g per unit width of the belt reinforcing portion 5 is larger than the cord total mass M2g per unit width of the belt reinforcing portion 5 overlapping the second shoulder land portion 3d in the tire radial direction D2, It is the composition of.

  According to such a configuration, the total cord mass M1g per unit width of the belt reinforcing portion 5 overlapping the first shoulder land portion 3c in the tire radial direction D2 overlaps the second shoulder land portion 3d in the tire radial direction D2 Since it is larger than the cord total mass M2g per unit width of the reinforcement part 5, it can suppress that the difference in the rigidity between a pair of shoulder land parts 3c and 3d becomes large.

  Further, in the pneumatic tire 1 according to the present embodiment, the belt reinforcing portion 5 includes edge reinforcing layers 52 and 53 overlapping the end of the belt portion 4 in the tire width direction D1 in the tire radial direction D2, The edge reinforcing layers 52 and 53 are configured to be disposed on the outer side in the tire width direction D1 than the main groove 3a disposed on the outermost side in the tire width direction D1.

  According to such a configuration, the edge reinforcing layers 52 and 53 are disposed outside the tire width direction D1 than the main grooves 3a disposed on the outermost side in the tire width direction D1. Thus, the edge reinforcing layers 52 and 53 are prevented from overlapping the shoulder main groove 3a in the tire radial direction D2, so that the belt reinforcing portion 5 is prevented from being positioned too close to the bottom of the shoulder main groove 3a. be able to.

  Moreover, in the pneumatic tire 1 according to the present embodiment, the second rubber portion 6b is configured to be disposed on the outer side when the vehicle is mounted.

  According to such a configuration, the second rubber portion 6b having a relatively large rubber hardness is arranged at the time of mounting on the vehicle, while the ground contact area of the outer area at the time of mounting on the vehicle becomes large at turning. . As a result, the rigidity of the outer region can be increased when the vehicle is mounted, so that the steering stability during turning can be improved.

  In the pneumatic tire 1 according to the present embodiment, the plurality of land portions 3c to 3g partitioned by the plurality of main grooves 3a and 3b and the ground contact end 2b and 2c are provided, and the first rubber portion 6a is used. The void ratio of the land portions 3c, 3e, 3g configured is smaller than the void ratio of the land portions 3d, 3f, 3g configured of the second rubber portion 6b.

  According to such a configuration, the void ratio of the land portions 3c, 3e, 3g constituted by the first rubber portion 6a having a relatively small rubber hardness is constituted by the second rubber portion 6b having a relatively large rubber hardness. It is smaller than the void ratio of land portions 3d, 3f, 3g. Thus, it is possible to suppress an increase in the difference in rigidity between land portions 3c, 3e, 3g on the first side D11 in the tire width direction D1 and land portions 3d, 3f, 3g on the second side D12.

  Further, the pneumatic tire 1 according to the present embodiment includes the center land portion 3g including the tire equatorial plane S1 by being divided by the plurality of main grooves 3a and 3b, and the interface 6c is the center land portion. It is configured to be located at 3g.

  According to such a configuration, since the interface 6c is located at the center land portion 3g, distortion generated at the interface 6c is a direct resistance to the road surface. Moreover, since the interface 6c is located at the center land portion 3g closest to the tire equatorial plane S1 against the contact pressure at the time of braking becoming larger as the tire equatorial plane S1 gets closer, strain generated at the interface 6c However, it is an effective resistance against the road surface.

  In addition, the pneumatic tire 1 is not limited to the structure of embodiment mentioned above, Moreover, it is not limited to the effect mentioned above. Of course, the pneumatic tire 1 can be variously modified without departing from the scope of the present invention. For example, as a matter of course, one or a plurality of configurations, methods, and the like according to various modifications described below may be arbitrarily selected and adopted as the configuration, the method, and the like according to the above-described embodiment.

(1) In the pneumatic tire 1 according to the embodiment, the ratio of the width dimension W1c of the first edge reinforcing layer 52 in which the first rubber portion 6a overlaps in the tire radial direction D2 to the width dimension W1a of the first rubber portion 6a The ratio (W2c / W2a) of the width dimension W2c of the second edge reinforcing layer 53 in which the second rubber portion 6b overlaps in the tire radial direction D2 with respect to the width dimension W2a of (W1c / W1a) The configuration is large. However, the pneumatic tire 1 is not limited to such a configuration.

  For example, the width dimension W1b of the respective reinforcing layers 51 and 52 in which the first rubber portion 6a overlaps in the tire radial direction D2 with respect to the width dimension W1a of the first rubber portion 6a by not only the configuration according to the embodiment but also other configurations. Of the second rubber portion 6b overlap in the tire radial direction D2 with respect to the width dimension W2a of the second rubber portion 6b. The ratio may be larger than the ratio of the sum of W2b and W2c (Σ (W2b, W2c) / W2a).

  According to such a configuration, the belt reinforcement portion in which the cord total mass M1a per unit width of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 overlaps the second rubber portion 6b in the tire radial direction D2 The total cord mass M2a per unit width can be larger than five.

(1-1) As an example of such a configuration, for example, a ratio of the width dimension W1b of the cap reinforcing layer 51 in which the first rubber portion 6a overlaps in the tire radial direction D2 to the width dimension W1a of the first rubber portion 6a (W1b / Even in a configuration in which W1a) is larger than the ratio (W2b / W2a) of the width dimension W2b of the cap reinforcing layer 51 in which the second rubber portion 6b overlaps in the tire radial direction D2 to the width dimension W2a of the second rubber portion 6b. Good.

(1-2) Also, as another example of such a configuration, for example, as shown in FIG. 9, the number of layers of the first edge reinforcing layer 52 (two layers in FIG. 9) is the second edge reinforcing layer The number of layers may be larger than the 53 layers (one layer in FIG. 9). The number of the edge reinforcing layers 52 and 53 is not particularly limited.

  Thus, the ratio (W1c × 2 / W1a) of the sum of the width dimension W1c of the first edge reinforcing layer 52 in which the first rubber portion 6a overlaps in the tire radial direction D2 with respect to the width dimension W1a of the first rubber portion 6a is The ratio (W2c / W2a) of the width dimension W2c of the second edge reinforcing layer 53 in which the second rubber portion 6b overlaps in the tire radial direction D2 with respect to the width dimension W2a of the 2 rubber portion 6b is larger.

  In FIG. 9, the ratio (W1c / W1a) of the width dimension W1c of the first edge reinforcing layer 52 per one layer where the first rubber portion 6a overlaps in the tire radial direction D2 with respect to the width dimension W1a of the first rubber portion 6a. Is the same as the ratio (W2c / W2a) of the width dimension W2c of the second edge reinforcing layer 53 in which the second rubber portion 6b overlaps in the tire radial direction D2 with respect to the width dimension W2a of the second rubber portion 6b. It is. For example, in the configuration according to FIG.

M1a> M2a
M1a = (W1b + W1c × 2) × M5 / W1a
M2a = (W2b + W2c) × M5 / W2a
W1b / W1a = W2b / W2a
W1c / W1a = W2c / W2a

(2) In the pneumatic tire 1 according to the above embodiment, the width dimensions W1b and W1c of the reinforcing layers 51 and 52 in which the first rubber portion 6a overlaps in the tire radial direction D2 with respect to the width dimension W1a of the first rubber portion 6a. The width dimension W2b of each reinforcing layer 51, 53 in which the second rubber portion 6b overlaps in the tire radial direction D2 with respect to the width dimension W2a of the second rubber portion 6b (W (W1b, W1c) / W1a) The ratio is larger than the ratio of the sum of W2c (Σ (W2b, W2c) / W2a). However, the pneumatic tire 1 is not limited to such a configuration.

(2-1) For example, as shown in FIG. 10, the number of ends of at least a part of the portion of the belt reinforcing portion 5 overlapping the first rubber portion 6 a in the tire radial direction D2 is It may be configured to be larger than the number of ends of the portion overlapping the second rubber portion 6b in the tire radial direction D2. According to such a configuration, the cord total mass M1a per unit width of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 is a belt reinforcing portion overlapping the second rubber portion 6b in the tire radial direction D2. The total cord mass M2a per unit width can be larger than five.

  In the belt reinforcing portion 5 according to FIG. 10, the ratio (W1c / W1a) of the width dimension W1c of the first edge reinforcing layer 52 in which the first rubber portion 6a overlaps in the tire radial direction D2 with respect to the width dimension W1a of the first rubber portion 6a. ) Is the same as the ratio (W2c / W2a) of the width dimension W2c of the second edge reinforcing layer 53 in which the second rubber portion 6b overlaps in the tire radial direction D2 with respect to the width dimension W2a of the second rubber portion 6b. It is a structure. For example, in the configuration according to FIG.

M1a> M2a
M1a = (W1b + W1c) × M5a / W1a
M2a = (W2b + W2c) × M5b / W2a
M5a> M5b
(W1b + W1c) / W1a = (W2b + W2c) / W2a
Here, M5a is the total mass of the cord 5a per unit width of the reinforcing layers 51 and 52 in which the first rubber portion 6a overlaps in the tire radial direction D2, and M5b is the second rubber portion 6b in the tire radial direction D2. It is the total mass of the cord 5a per unit width of the reinforcing layers 51 and 53 which overlap.

(2-2) Further, for example, the weight per unit length and unit width of the cord 5a of at least a part of the portion of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 is a belt The reinforcing portion 5 may be configured to be larger than the mass per unit length and unit width of the cord 5a of the portion overlapping the second rubber portion 6b in the tire radial direction D2. According to such a configuration, the cord total mass M1a per unit width of the belt reinforcing portion 5 overlapping the first rubber portion 6a in the tire radial direction D2 is a belt reinforcing portion overlapping the second rubber portion 6b in the tire radial direction D2. The total cord mass M2a per unit width can be larger than five.

  As an example of such a configuration, for example, the configuration may be such that the unit length and the mass per unit width of the cord 5a are different due to the difference in diameter of the cord 5a. The diameter of the cord 5a of at least a portion of the portion overlapping the first rubber portion 6a in the tire radial direction D2 is larger than the diameter of the cord 5a of the portion overlapping the second rubber portion 6b in the tire radial direction D2. , May be used.

  In addition, as another example of such a configuration, for example, the configuration may be such that the unit length and the mass per unit width of the cord 5a are different by changing the material of the cord 5a. Then, the mass (density) per unit volume of the cord 5a of at least a portion of the portion overlapping the first rubber portion 6a in the tire radial direction D2 is the cord in a portion overlapping the second rubber portion 6b in the tire radial direction D2 The configuration may be larger than the mass (density) per unit volume of 5a.

(3) Further, in the pneumatic tire 1 according to the embodiment, the cord total mass M1d per unit width of the belt reinforcing portion 5 overlapping the first ground contact area 6d in the tire radial direction D2 is the second ground area 6e. And the total cord mass M2d per unit width of the belt reinforcing portion 5 overlapping in the tire radial direction D2 is larger than the total cord mass M2d. However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable.

  For example, the total cord mass M1d per unit width related to the first ground region 6d may be the same as the total cord mass M2d per unit width related to the second ground region 6e, or For example, the configuration may be smaller than the total cord mass M2d per unit width related to the second ground region 6e.

(4) Further, in the pneumatic tire 1 according to the embodiment, the cord total mass M1g per unit width of the belt reinforcing portion 5 overlapping the first shoulder land portion 3c in the tire radial direction D2 is the second shoulder land. The belt reinforcement portion 5 overlapping in the tire radial direction D2 with the portion 3d is larger than the total cord mass M2g per unit width. However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable.

  For example, the cord total mass M1g per unit width related to the first shoulder land portion 3c may be the same as the cord total mass M2g per unit width related to the second shoulder land portion 3d. Alternatively, for example, the configuration may be smaller than the total cord mass M2g per unit width related to the second shoulder land portion 3d.

(5) Further, in the pneumatic tire 1 according to the above-described embodiment, the edge reinforcing layers 52 and 53 are disposed on the outer side in the tire width direction D1 than the main groove 3a disposed on the outermost side in the tire width direction D1. It is the composition that is done. However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable. For example, the edge reinforcing layers 52 and 53 may be configured to overlap the main groove 3a disposed on the outermost side in the tire width direction D1 in the tire radial direction D2.

(6) Further, in the pneumatic tire 1 according to the above-described embodiment, the second rubber portion 6b is disposed outside when the vehicle is mounted. However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable. For example, the second rubber portion 6b may be arranged inside when the vehicle is mounted.

(7) Further, in the pneumatic tire 1 according to the above-described embodiment, the void ratio of the land portions 3c, 3e, 3g formed of the first rubber portion 6a is the land portion 3d formed of the second rubber portion 6b. , 3f, and 3g are smaller than the void ratio. However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable.

  For example, the void ratio of land portions 3c, 3e, 3g formed of the first rubber portion 6a is the same as the void ratio of land portions 3d, 3f, 3g formed of the second rubber portion 6b. Alternatively, for example, the void ratio of the land portions 3d, 3f, 3g formed by the second rubber portion 6b may be larger.

(8) Further, the pneumatic tire 1 according to the above-described embodiment is configured to be a tire whose mounting direction to a vehicle is designated. However, the pneumatic tire 1 is not limited to such a configuration. For example, the pneumatic tire 1 may be configured to be a tire whose mounting direction to a vehicle is not designated. In such a configuration, the tread pattern has a shape that is point symmetrical with respect to an arbitrary point on the tire equator, or a shape that is symmetrical with respect to the tire equator.

(9) Moreover, in the pneumatic tire 1 according to the above-described embodiment, the belt reinforcing portion 5 includes the cap reinforcing layer 51 and the edge reinforcing layers 52 and 53. However, the pneumatic tire 1 is not limited to such a configuration. For example, the belt reinforcing portion 5 may include only the cap reinforcing layer 51. For example, the belt reinforcing portion 5 may include only the edge reinforcing layers 52 and 53.

  DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 2 ... Tread part, 2a ... Tread surface, 2b ... 1st grounding end, 2c ... 2nd grounding end, 2d ... 1st tread outer end, 2e ... 2nd tread outer end, 2f ... Shoulder land Part inner end (shoulder main groove outer end), 2g ... shoulder land inner end (shoulder main groove outer end), 3 ... tread rubber, 3a ... shoulder main groove, 3b ... center main groove, 3c ... first shoulder land portion, 3d ... 2nd shoulder land section, 3e ... middle land section (media land section), 3 f ... middle land section (media land section) 3 g ... middle land section (center land section), 3 h ... land groove (width groove), 3i: land groove (sipe), 4: belt portion, 5: belt reinforcing portion, 5a: cord, 5b: topping rubber, 6: rubber surface portion, 6a: first rubber portion, 6b: second rubber portion, 6c: Interface, 6d: first ground region, 6e: second ground region DESCRIPTION OF SYMBOLS 7 ... rubber inner layer part, 11 ... bead part, 12 ... sidewall part, 12 a ... sidewall rubber, 13 ... carcass layer, 14 ... inner liner layer, 20 ... rim, 41 ... first belt layer, 42 ... second belt Layers 51: Cap reinforcing layer 51a: first end 51b: second end 52: first edge reinforcing layer 52a: first end 52b: second end 53: second edge reinforced Layer 53a: first end 53b: second end D1: tire width direction D2: tire radial direction D3: tire circumferential direction D11: first width direction side (first side) D12: first 2 width direction side (second side), S1 ... tire equatorial plane

Claims (7)

A pneumatic tire comprising a plurality of main grooves extending in the tire circumferential direction, the pneumatic tire comprising:
A rubber surface layer portion having an outer surface in the tire radial direction, a belt portion disposed inside the tire surface in the tire radial direction with respect to the rubber surface layer portion, and a cord inclined from the tire circumferential direction A belt reinforcing portion disposed on the outer side in the tire radial direction and the cord disposed along the tire circumferential direction;
The rubber surface layer portion includes a first rubber portion formed of a first rubber, and a second rubber portion formed of a second rubber having a rubber hardness greater than that of the first rubber,
The first rubber portion is disposed on the first side in the tire width direction,
The second rubber portion is disposed on the second side in the tire width direction,
The interface between the first rubber portion and the second rubber portion is disposed between a pair of main grooves disposed at the outermost side in the tire width direction,
The cord total mass per unit width of the belt reinforcing portion overlapping the first rubber portion in the tire radial direction is the cord total mass per unit width of the belt reinforcing portion overlapping the second rubber portion in the tire radial direction Greater than pneumatic tires. The first rubber portion includes a first ground contact region from the ground contact end on the first side in the tire width direction to the interface,
The second rubber portion includes a second contact area from the contact end on the second side in the tire width direction to the interface.
The cord total mass per unit width of the belt reinforcing portion overlapping the first ground contact region in the tire radial direction is the cord total mass per unit width of the belt reinforcing portion overlapping the second ground contact region in the tire radial direction The pneumatic tire according to claim 1, which is larger than that. Divided by a first shoulder land portion defined by a main groove disposed on the first side in the tire width direction and a ground contact end, and by a main groove disposed on the second side in the tire width direction and the ground end And the second shoulder land portion
The cord total mass per unit width of the belt reinforcing portion overlapping the first shoulder land portion in the tire radial direction is the code per unit width of the belt reinforcing portion overlapping the second shoulder land portion in the tire radial direction The pneumatic tire according to claim 1, which is larger than a total mass. The belt reinforcing portion includes an edge reinforcing layer overlapping in the tire radial direction with an end of the belt portion in the tire width direction,
The pneumatic tire according to any one of claims 1 to 3, wherein the edge reinforcing layer is disposed on the outer side in the tire width direction than a main groove disposed on the outermost side in the tire width direction.   The pneumatic tire according to any one of claims 1 to 4, wherein the second rubber portion is disposed outside when the vehicle is mounted. A plurality of land portions defined by the plurality of main grooves and the ground end;
The air-filled according to any one of claims 1 to 5, wherein the void ratio of the land portion formed of the first rubber portion is smaller than the void ratio of the land portion formed of the second rubber portion. tire. A center land portion including a tire equatorial plane is provided by being divided by the plurality of main grooves,
The pneumatic tire according to any one of claims 1 to 5, wherein the interface is located at the center land portion.

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