JP5458778B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire suitable for improving center wear resistance of a tread portion while suppressing generation of noise.

  In a pneumatic tire, the drainage is improved by a main groove formed in the tread portion along the tire circumferential direction, thereby ensuring running stability on a road surface wet by rain or the like. However, the main groove causes air column resonance noise when the vehicle travels.

  Therefore, conventionally, in the pneumatic tire shown in Patent Document 1, in the pneumatic tire in which a plurality of main grooves extending along the tire circumferential direction are provided on both sides of the tire equatorial plane in the tread portion, the tire ground contact width is TW. When the length from the tire equatorial plane to the outer side wall of the main groove located on the outermost side in the tire width direction is L0, the condition of 0.3 (TW / 2) <L0 <0.6 (TW / 2) Meet. Moreover, in the pneumatic tire disclosed in Patent Document 1, one end extends along the tire width direction in which one end portion communicates with the main groove located on the outermost side in the tire width direction and the other end portion does not communicate with the tire ground contact end. A lug groove and a second lug groove extending along the tire width direction in which one end portion does not communicate with the main groove located on the outermost side in the tire width direction and the other end portion communicates with the tire ground contact end in the tire circumferential direction. A plurality of them are provided alternately, and the end portions of the first lug groove and the second lug groove have a predetermined overlap margin in the tire width direction.

  The pneumatic tire disclosed in Patent Literature 1 reduces medium-frequency road noise by providing a main groove located on the outermost side in the tire width direction from the tire equatorial plane at a position approaching the tire equatorial plane side. And the pneumatic tire of patent document 1 can maintain a high drainage property by providing a main groove, a 1st lug groove, and a 2nd lug groove, and can improve driving | running | working stability, and a tire width direction Since the first lug groove and the second lug groove between the outermost main groove and the tire ground contact edge are cut in the middle, and the first lug groove and the second lug groove have an overlap, the main groove The air column resonance noise generated in step 1 is suppressed from being transmitted from each lug groove to the outside as high-frequency road noise.

JP 2009-12533 A

  However, like the pneumatic tire of Patent Document 1, when the main groove located on the outermost side in the tire width direction from the tire equator surface is provided at a position approaching the tire equator line side, the main groove is formed in the tread portion. The land portion near the tire equator plane has a relatively narrow tire width direction dimension, and the rigidity is lowered. For this reason, since the contact length in the tire circumferential direction of the land portion near the tire equator surface becomes long and wear energy increases, center wear (wear near the tire equator surface) tends to occur.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve center abrasion resistance, suppressing generation | occurrence | production of noise.

In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention is provided with at least three main grooves extending in the tire circumferential direction in the tread portion, the tire ground contact width is TW, and the tire When the length from the equator plane to the outer side wall of the main groove located on the outermost side in the tire width direction is L0, the condition of 0.3 (TW / 2) ≦ L0 ≦ 0.6 (TW / 2) is satisfied. The pneumatic tire to be filled includes a belt reinforcing layer that covers a belt layer provided on the outer side in the tire radial direction of the carcass along the tire circumferential direction on the outer side in the tire radial direction, and the belt reinforcing layer extends from the tire equatorial plane to the tire. A groove along the tire circumferential direction in the tire radial direction inner side of the main groove located on the outermost side in the width direction and having a width W2 with respect to the groove width W1 of the main groove in a range of 1.0 ≦ W2 / W1 ≦ 3.0 under groove provided in the lower region Strength layer, and is constructed by dividing only the shoulder reinforcing layer covering the tire widthwise end portions of the belt layer, the ratio of the tensile stiffness index Ec of the groove bottom reinforcement layer, and tensile stiffness index Es of the shoulder reinforcing layer Ec / Es satisfies the condition of 1.0 <Ec / Es ≦ 10.0.

  According to this pneumatic tire, the restraining force of the belt reinforcing layer in the region below the groove, which is the inner side in the tire radial direction of the main groove located on the outermost side in the tire width direction from the tire equatorial plane, is increased. For this reason, the main groove is provided at a position close to the tire equator line side to form a pattern having high drainage and reducing road noise, and the first land portion arranged closest to the tire equator line A situation in which the contact length in the tire circumferential direction becomes long can be prevented. As a result, since center wear can be suppressed, the center wear resistance can be improved while suppressing the generation of noise.

  In the pneumatic tire of the present invention, the other main groove is formed narrower than the main groove located on the outermost side in the tire width direction from the tire equatorial plane.

  According to this pneumatic tire, the generation of noise can be suppressed due to the relatively narrow groove width of the other main grooves, and the groove width of the main groove located on the outermost side in the tire width direction from the tire equator surface is relatively wide. This improves drainage. For this reason, the effect of suppressing noise and the effect of improving drainage can be obtained remarkably.

  In the pneumatic tire of the present invention, the groove width W3 of the other main groove is 1.10 ≦ W1 / with respect to the groove width W1 of the main groove located on the outermost side in the tire width direction from the tire equatorial plane. It is set in the range of W3 ≦ 1.50.

  According to this pneumatic tire, by setting the groove widths W1 and W3, it is possible to more significantly obtain the noise suppressing effect and the drainage improving effect.

  The pneumatic tire according to the present invention can improve the center wear resistance while suppressing the generation of noise.

FIG. 1 is a plan view showing a tread portion of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a meridional sectional view of the pneumatic tire according to the embodiment of the present invention. FIG. 3 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention .

  Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  In the following description, the tire width direction refers to a direction parallel to the rotation axis (not shown) of the pneumatic tire 1, and the inner side in the tire width direction refers to the tire equator plane (tire equator line) C in the tire width direction. The heading direction and the outer side in the tire width direction refer to the side away from the tire equatorial plane C in the tire width direction. The tire circumferential direction is a circumferential direction with the rotation axis as a central axis. Further, the tire radial direction refers to a direction orthogonal to the rotation axis, the tire radial inner side is the side toward the rotation axis in the tire radial direction, and the tire radial direction outer side is the side away from the rotation axis in the tire radial direction. Say.

The pneumatic tire 1 described below is configured to be substantially symmetric with respect to the tire equatorial plane C. The tire equatorial plane C is a plane that is orthogonal to the rotational axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane C in the tire width direction. The tire equator line is a line on the tire equator plane C and along the circumferential direction of the pneumatic tire 1. In the present embodiment, the same sign “C” as that of the tire equator plane is attached to the tire equator line. Since the pneumatic tire 1 described below is configured to be substantially symmetric about the tire equatorial plane C, the pneumatic tire 1 is cut along a plane passing through the rotation axis of the pneumatic tire 1. in meridional section (FIG. 2) when the one side around the tire equatorial plane C shows only (Oite right in FIG. 2) describes only the one side, the other side (in FIG. 2 The description on the left side is omitted.

[Embodiment 1]
First, the pattern of the pneumatic tire 1 will be described. The pneumatic tire 1 is suitable as a tire mounted on a general passenger car. As shown in FIG. 1, the pneumatic tire 1 has a tread portion 2. The tread portion 2 is made of a rubber material and is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. The surface of the tread portion 2 is formed as a tread surface 21 that is a surface that comes into contact with the road surface when a vehicle (not shown) on which the pneumatic tire 1 is mounted travels. In the tread surface 21, tire contact width ends T are set at predetermined positions on both outer sides in the tire width direction, and the tire contact width direction interval between the tire contact width ends T is set as the tire contact width TW. .

  Here, the tire ground contact width TW means that when the pneumatic tire 1 is assembled on a regular rim and filled with a regular internal pressure and 70% of the regular load is applied, the tread surface 21 of the pneumatic tire 1 is the road surface. It is the maximum width in the tire width direction of the tire contact area, which is the area that contacts the ground. Further, the tire ground contact width end T refers to both outermost ends in the tire width direction of the tire contact area, and the tire contact width end T is shown continuously in the tire circumferential direction as shown in FIG.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “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 “maximum load capacity” defined by JATMA, a maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

  Furthermore, the pneumatic tire 1 of the present embodiment has at least three main grooves 22 that are straight main grooves extending along the tire circumferential direction and parallel to the tire equator line C on the tread surface 21 of the tread portion 2. Is provided. The main groove 22 includes a first main groove 22a disposed closest to the tire equator line C (on the tire equator line C in the present embodiment) and a second main groove 22b disposed on the outermost side in the tire width direction. And have. A plurality of rib-like land portions 23 extending along the tire circumferential direction and parallel to the tire equator line C are formed on the tread surface 21 by the plurality of main grooves 22. The four land portions 23 in the present embodiment are provided on the tread surface 21 and are disposed between the first main groove 22a and the second main groove 22b and are disposed closest to the tire equator line C. Part 23a and the 2nd land part 23b arrange | positioned in the tire width direction outer side of the tread surface 21 at the tire width direction outer side of the 2nd main groove 22b.

  The first land portion 23a is provided with a plurality of sub-grooves 24 communicating with the first main groove 22a and the second main groove 22b and dividing the first land portion 23a into a plurality of portions in the tire circumferential direction at predetermined intervals in the tire circumferential direction. It has been. In addition, the first land portion 23a includes a plurality of inclined grooves 25 that are inclined with respect to the tire circumferential direction so as to intersect with a plurality of (two in the present embodiment) sub-grooves 24 at predetermined intervals in the tire circumferential direction. Is provided. Furthermore, a sipe 26 that intersects the inclined groove 25 is provided in the first land portion 23a. The sipe 26 communicates with the second main groove 22b but does not communicate with the first main groove 22a. The second land portion 23b is provided with a plurality of sub-grooves 27 communicating with the second main groove 22b and dividing the second land portion 23b into a plurality of portions in the tire circumferential direction at predetermined intervals in the tire circumferential direction. Further, a sipe 28 is provided in the second land portion 23b. This sipe 28 intersects the tire ground contact width end T and does not communicate with the second main groove 22b.

  In the pneumatic tire 1 of the present embodiment having such a pattern, the tire starts from the side wall 22ba on the outer side in the tire width direction of the second main groove 22b which is the main groove 22 located on the outermost side in the tire width direction at the time of inflation. When the length in the tire width direction up to the equator line C is L0, the relationship between this L0 and the tire ground contact width TW is 0.3 (TW / 2) ≦ L0 ≦ 0.6 (TW / 2). Fulfill. The side wall 22ba on the outer side in the tire width direction of the second main groove 22b refers to the position of the outer end in the tire width direction at the opening portion of the second main groove 22b. In addition, the groove width (tire width direction width) of the 1st main groove 22a and the 2nd main groove 22b is set to the range of 5 mm or more and 20 mm or less.

  According to the pneumatic tire 1, drainage can be improved by the main groove 22. Moreover, according to this pneumatic tire 1, the relationship between the tire width direction length L0 from the outer side wall 22ba of the second main groove 22b to the tire equator line C and the tire ground contact width TW is set. Thus, the second main groove 22b is provided at a position closer to the tire equator line C side as compared with a general pneumatic tire for passenger cars. For this reason, it becomes possible to reduce medium frequency road noise and high frequency road noise. It should be noted that the relationship between L0 and tire ground contact width TW is in the range of 0.33 (TW / 2) ≦ L0 ≦ 0.55 (TW / 2), which improves drainage and improves medium frequency road noise and This is preferable for reducing high-frequency road noise.

  Next, a configuration including the inside of the pneumatic tire 1 will be described. As shown in FIG. 2, the pneumatic tire 1 of the present embodiment includes a shoulder portion 3 on both sides of the tread portion 2, a sidewall portion and a bead portion that are successively shown from the shoulder portions 3, although not clearly shown in the drawing. have. The pneumatic tire 1 includes a carcass 4, a belt layer 5, and a belt reinforcing layer 6.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. The sidewall portion is exposed at the outermost side in the tire width direction of the pneumatic tire 1. Moreover, a bead part has a bead core and a bead filler. The bead core is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler is disposed in a space formed by folding the end of the carcass 4 outward in the tire width direction at the position of the bead core.

  The carcass 4 is configured such that each tire width direction end portion is folded back with respect to a pair of bead portions and is wound around in a toroidal shape in the tire circumferential direction to constitute a tire skeleton. The carcass 4 is a carcass cord such as organic fiber (nylon, polyester, rayon, etc.) or steel covered with a rubber material. A plurality of carcass cords are arranged in parallel in the tire circumferential direction while being along the tire meridian direction perpendicular to the tire equator line C of the pneumatic tire 1. It should be noted that the carcass cord has an angle with respect to the tire equator line C (tire circumferential direction) substantially 90 [degrees], and is −5 [degrees] to +5 [degrees] with respect to 90 degrees with respect to the tire equator line C Includes range angles. In addition, the carcass 4 is composed of one layer as shown in FIG. 2, but it may have a multilayer structure in order to improve tire rigidity.

  The belt layer 5 has a multilayer structure in which at least two belts 51 and 52 are laminated, and is disposed on the outer side in the tire radial direction, which is the outer periphery of the carcass 4, and covers the carcass 4 in the tire circumferential direction in the tread portion 2. The belts 51 and 52 are made of a cord made of organic fiber (nylon, polyester, rayon, etc.) or steel covered with a rubber material, and the cord is at a predetermined angle with respect to the tire equator line C (tire circumferential direction). Is placed. Further, the belts 51 and 52 are arranged with their cords inclined in opposite directions with respect to the tire equator line C.

  The belt reinforcing layer 6 is disposed outside the belt layer 5 in the tire radial direction and covers the belt layer 5 along the tire circumferential direction. The belt reinforcing layer 6 is made of a cord made of organic fibers (nylon, polyester, rayon, etc.) or steel covered with a rubber material. The cord is -5 [degrees] with respect to the tire equator line C (tire circumferential direction). ] To +5 [degrees]. The belt reinforcing layer 6 is mainly provided by winding a strip-like strip material (for example, a width of 10 [mm]) in the tire circumferential direction.

  The belt reinforcing layer 6 is disposed in a groove lower region provided on the inner side in the tire radial direction in the normal direction of the tread surface 21 of the second main groove 22b located on the outermost side in the tire width direction from the tire equatorial plane C. At least a sub-groove reinforcing layer 61 is provided. The lower groove region is set along the tire circumferential direction so that the tire width direction width W2 with respect to the groove width W1 which is the width in the tire width direction of the second main groove 22b is in the range of 1.0 ≦ W2 / W1 ≦ 3.0. ing. Further, the under-groove region is set to overlap the second main groove 22b in the tire radial direction at least in the range of the groove bottom width in the second main groove 22b. The groove bottom width refers to the distance between each intersection of the extension line of the opposing groove wall surface of the second main groove 22b and the extension line extending in the tire width direction along the tread surface 21 from the groove bottom. (See FIG. 2). The belt reinforcing layer 6 has a ratio Ec / Es between the tensile stiffness index Ec in the region below the groove and the tensile stiffness index Es in the region excluding the region below the groove, 1.0 <Ec / Es ≦ 10.0. Meet the conditions.

As shown in FIG. 2, there is a shoulder region in which the shoulder reinforcing layer 62 that covers the tire width direction end portion of the belt layer 5 along the tire circumferential direction is disposed in the region excluding the sub-groove region .

Here, the tensile stiffness indexes Ec and Es are the initial modulus M [kgf / mm ² ] of the cord constituting the belt reinforcing layer 6, the strand diameter d [mm], the number of strands of cord n [lines], the cord end the number E [present / 50 mm], the number of stacked layers n [sheets] of the belt reinforcing layer 6, from the cord angle theta [degrees], determined by the equation ^{M × (πd 2/4)} × n × E × n × cos 4 θ Belt rigidity coefficient G [kgf / mm]. The initial modulus M is an elastic coefficient in the cord length direction when a tension of 4.5 [kgf] is applied to the cord, and the number of strands n is the number of strands constituting the cord. The number E is the number of cords existing in a width of 50 mm in a direction perpendicular to the cord of the belt reinforcing layer 6 after vulcanization, and the cord angle θ is an angle formed by the cord with the tire circumferential direction. That is, the ratio Ec / Es represents the initial modulus M [kgf / mm ² ] of the cord constituting the belt reinforcing layer 6, the strand diameter d [mm], the number of strands of the cord n [lines], and the number of cord ends E It is determined by [number / 50 mm], the number N of the belt reinforcing layers 6 stacked, and the cord angle θ [degree]. Further, the tensile stiffness indexes Ec and Es are also expressed by the tension at which the strip material is wound before vulcanization. That is, the ratio Ec / Es is determined by winding the strip material while applying a high tension to the strip material in the region below the groove and lowering the tension applied to the strip material in the region other than the region below the groove.

  According to the pneumatic tire 1, in the belt reinforcing layer 6, the second main groove 22b located on the outermost side in the tire width direction from the tire equatorial plane C is on the inner side in the tire radial direction and the groove of the second main groove 22b. The tensile stiffness index Ec in the region below the groove along the tire circumferential direction when the width W2 with respect to the width W1 is in the range of 1.0 ≦ W2 / W1 ≦ 3.0 is compared with the tensile stiffness index Es in the region excluding the region below the groove. As a result, the restraining force of the belt reinforcing layer 6 in the region below the groove, which is the inner side in the tire radial direction of the second main groove 22b, is increased.

  Therefore, the main groove 22 is provided at a position close to the tire equator line C side to form a pattern of the tread portion 2 having high drainage and reducing road noise, and the pneumatic tire 1 is rimmed into a regular rim. Assembling and filling the normal internal pressure and applying 70% of the normal load, the ground contact length in the tire circumferential direction of the first land portion 23a disposed closest to the tire equator line C is increased. Can be prevented. As a result, since center wear can be suppressed, it becomes possible to improve center wear resistance while suppressing noise generation. In addition, by increasing the tensile stiffness index Ec of a specific portion such as in the sub-groove region, it is possible to suppress an unnecessary increase in weight of the pneumatic tire 1.

  In the pneumatic tire 1 of the present embodiment, the tensile stiffness index ratio Ec / Es is preferably set in a range of 1.5 ≦ Ec / Es ≦ 7.5.

  When the ratio Ec / Es of the tensile stiffness index is less than 1.5, the effect of suppressing the center wear is small. On the other hand, when the ratio Ec / Es of the tensile stiffness index exceeds 7.5, the belt reinforcing layer 6 in the region excluding the groove below region has too high restraint force, so that wear in the region excluding the groove under region ( For example, shoulder wear may occur. Therefore, by further defining the range of the tensile stiffness index ratio Ec / Es as described above, it is possible to suppress center wear and to improve center wear resistance while suppressing noise generation. .

  Further, in the pneumatic tire 1 of the present embodiment, the belt reinforcing layer 6 is provided by winding the strip material, and the strip material is wound around the groove in the region below the groove.

  According to this pneumatic tire 1, the number of overlapping strip materials and the width of the strip material can be adjusted in the region below the groove, and the strip material can be wound with little or no overlap in the region other than the region below the groove. It is possible to set the desired tensile stiffness index ratio Ec / Es.

  In the pneumatic tire 1 of the present embodiment, the main groove 22 (second main groove 22b) located on the outermost side in the tire width direction from the tire equatorial plane C is another main groove 22 (first main groove). 22a) is formed with a narrow groove width.

  According to the pneumatic tire 1, the generation of noise can be suppressed because the groove width of the first main groove 22a is relatively narrow, and the drainage performance is improved because the groove width of the second main groove 22b is relatively wide. For this reason, it becomes possible to obtain significantly the effect of suppressing noise and the effect of improving drainage.

  Further, in the pneumatic tire 1 of the present embodiment, other main grooves 22 (with respect to the groove width W1 of the main groove 22 (second main groove 22b) located on the outermost side in the tire width direction from the tire equatorial plane C The groove width W3 of the first main groove 22a) is set in the range of 1.10 ≦ W1 / W3 ≦ 1.50.

  According to the pneumatic tire 1, the groove width W1 of the first main groove 22a and the groove width W3 of the second main groove 22b are set, so that the noise suppression effect and the drainage improvement effect are more prominent. It becomes possible to obtain.

  In this example, for a plurality of types of pneumatic tires having different conditions, quietness (occurrence of medium frequency road noise (315 Hz band) and high frequency road noise (1 kHz band)), wear resistance (center wear resistance), and Performance tests on tire mass were conducted.

  In this performance test, a pneumatic tire having a tire size of 195 / 65R15 was assembled to a regular rim, filled with a regular internal pressure, loaded with a regular load, and mounted on a test vehicle (domestic 2.0-liter class sedan type passenger car).

  As for the evaluation method, in quietness, when driving on a rough road surface with the above test vehicle at 60 km / h, the sound of medium frequency road noise (315 Hz band) and high frequency road noise (1 kHz band) near the driver side window. Measure the pressure level. This evaluation is indicated by an index value with the conventional pneumatic tire as a reference (100). The larger the index value, the smaller the sound pressure level and the better the silence. For friction resistance, the test vehicle travels on a paved road surface at 10,000 [km], and after running, the groove depth in the main groove is measured at four locations in the tire circumferential direction to obtain an average. The average groove depth in all the main grooves is obtained from the sum of the averages of the respective groove depths, and the wear amount (unit: mm) of the land portion close to the tire equatorial plane is obtained. Then, the travelable distance [km] that can travel until the remaining groove depth reaches 1.6 mm is calculated, and the average wearable distance of each groove is calculated to obtain the estimated wear life. This evaluation is indicated by an index value with a conventional pneumatic tire as a reference (100), and the larger the index value, the longer the wear life is preferable. Moreover, the mass of the pneumatic tire before a test is measured by the mass of a tire. This evaluation is indicated by an index value based on the conventional pneumatic tire as a reference (100), and the smaller the index value, the lighter and more preferable the mass.

  The pneumatic tire of the conventional example is provided with at least three main grooves extending along the tire circumferential direction in the tread portion, the tire ground contact width is TW, and the second is located on the outermost side in the tire width direction from the tire equatorial plane. When the length to the outer side wall of the main groove is L0, the condition of 0.3 (TW / 2) ≦ L0 ≦ 0.6 (TW / 2) is satisfied, but the belt reinforcing layer is the shoulder reinforcing layer only. It is. The pneumatic tire of the comparative example satisfies the condition of 0.3 (TW / 2) ≦ L0 ≦ 0.6 (TW / 2), and the belt reinforcement layer is a shoulder reinforcement layer and a sub-groove reinforcement layer. In the pneumatic tires of Comparative Example 1 and Comparative Example 2, W2 / W1 in the region below the groove with respect to the main groove width is not optimized. Further, in the pneumatic tire of Comparative Example 3, W2 / W1 in the sub-groove region with respect to the main groove width is optimized, but the tensile stiffness index ratio Ec / Es is not optimized. On the other hand, the pneumatic tire of the example satisfied the condition of 0.3 (TW / 2) ≦ L0 ≦ 0.6 (TW / 2), and the belt reinforcing layer was a shoulder reinforcing layer and a sub-groove reinforcing layer. Thus, the W2 / W1 of the region under the groove and the tensile stiffness index ratio Ec / Es are optimized with respect to the width of the main groove.

  As shown in the test results of FIG. 5, in the pneumatic tires of Examples 1 to 8, quietness (occurrence of medium frequency road noise (315 Hz band) and high frequency road noise (1 kHz band)), and wear resistance, respectively. It can be seen that the property (center wear resistance) is improved and the increase in the mass of the tire is suppressed.

  As described above, the pneumatic tire according to the present invention is suitable for improving the center wear resistance while suppressing the generation of noise.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 21 Tread surface 22 Main groove 22a First main groove 22b Second main groove 22ba Outer side wall 23 Land part 23a First land part 23b Second land part 3 Shoulder part 4 Carcass 5 Belt layers 51, 52 Belt 6 Belt reinforcing layer 61 Reinforcing groove layer 62 Shoulder reinforcing layer 63 Total reinforcing layer C Tire equator surface (tire equator line)
Ec, Es Tensile rigidity index T Tire contact width end TW Tire contact width W1 Groove width of second main groove W2 Width of groove lower region W3 Groove width of first main groove

Claims (3)

The tread portion is provided with at least three main grooves extending in the tire circumferential direction, the tire contact width is TW, and the length from the tire equatorial plane to the outer side wall of the main groove located on the outermost side in the tire width direction In a pneumatic tire satisfying the condition of 0.3 (TW / 2) ≦ L0 ≦ 0.6 (TW / 2) where L0 is L0,
A belt reinforcement layer that covers the belt layer provided on the outer side in the tire radial direction of the carcass along the tire circumferential direction on the outer side in the tire radial direction,
The belt reinforcing layer is located on the innermost side in the tire radial direction of the main groove located on the outermost side in the tire width direction from the tire equatorial plane, and a width W2 with respect to the groove width W1 of the main groove is 1.0 ≦ W2 / W1 ≦ 3. The sub-groove reinforcement layer is configured by being divided only by a sub-groove reinforcement layer provided in a region below the groove along the tire circumferential direction in a range of 0.0 and a shoulder reinforcement layer that covers an end of the belt layer in the tire width direction. A pneumatic tire characterized in that a ratio Ec / Es of the tensile stiffness index Ec of the shoulder reinforcement layer and the tensile stiffness index Es of the shoulder reinforcing layer satisfies a condition of 1.0 <Ec / Es ≦ 10.0. 2. The pneumatic tire according to claim 1 , wherein the other main groove is formed with a narrow groove width with respect to the main groove located on the outermost side in the tire width direction from the tire equatorial plane. The groove width W3 of the other main groove is set in a range of 1.10 ≦ W1 / W3 ≦ 1.50 with respect to the groove width W1 of the main groove located on the outermost side in the tire width direction from the tire equator plane. The pneumatic tire according to claim 2 , wherein

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