JP5181581B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve grip performance and wet performance on a dry road surface.

  Conventional pneumatic tires ensure high grip performance and wet performance on dry road surfaces by devising the cross-sectional shape of the main groove and the profile of the tread portion. However, with a wide and low-flat performance tire, it is difficult to achieve a balance between these performances. Further, there is a demand for improving the uneven wear resistance performance of such pneumatic tires.

  As a conventional pneumatic tire related to such a problem (steering stability), a technique described in Patent Document 1 is known. A conventional pneumatic tire (a pneumatic radial tire excellent in steering stability) includes a cylindrical crown portion and sidewall portions extending radially inward from both ends of the crown portion. Pneumatic radial that is reinforced with a radial carcass that extends through the crown and over the other sidewall, and that has a belt layer of non-stretchable cord that extends across the entire width of the tread between the radial carcass and the tread placed on the crown The contour curve of the tread surface that protrudes radially outward of the tire in the cross section including the rotation axis of the tire when the specified internal pressure is filled after the applied rim is mounted is the tread centered on the tire equator. At least 2.5 times the tire radius in the central tread area, which occupies 25-40% of the width A tread side section that has a radius of curvature and has a curvature radius that is smaller than the curvature radius in the tread central section in the tread side section continuously connected to both sides of the tread central section, and the tire rotation axis perpendicular to the tread end; The intersection with the line parallel to the tire rotation axis through the point on the tread surface where the distance to the tread surface measured along the perpendicular is maximum, and the extension line of the contour curve of the tread side area and the perpendicular The distance between the intersections with each other is in the range of 5.5 to 7.5% of the tread width.

JP-A-4-237608

  An object of the present invention is to provide a pneumatic tire that can improve grip performance and wet performance on a dry road surface.

In order to achieve the above object, a pneumatic tire according to the present invention has a plurality of circumferential main grooves extending in the tire circumferential direction and a land portion defined by the circumferential main grooves in a tread portion. In a pneumatic tire, a tread portion is partitioned into two tread regions with a tire equator line CL as a boundary in a cross-sectional view in the tire meridian direction when the vehicle is mounted, and the profiles of the tread regions are different from each other. The profile arc which is composed of one or three profile arcs and which is drawn from the point A on the tire equator line CL in the vehicle width direction and is on the outermost side in the tire width direction in the tread region on the inner side in the vehicle width direction; When the intersection point of the shoulder portion with the profile arc is a point B and when a straight line m connecting the point B and the point A is drawn, an angle θ formed by the straight line l and the straight line m is [Deg] Ri range near the ≦ θ ≦ 10 [deg], in the groove wall angle α in the vehicle width direction inner groove wall located in the inner vehicle width direction outer side of the both groove wall of the circumferential main groove groove wall And the groove wall angles α and β of the circumferential main groove are 15 [deg] ≦ α ≦ 35 [deg] and 20 [deg] ≦ β ≦. It is in the range of 50 [deg] .
Further, the pneumatic tire according to the present invention is a pneumatic tire having a plurality of circumferential main grooves extending in the tire circumferential direction and land portions defined by these circumferential main grooves in a tread portion. The tread portion is partitioned into two tread regions with the tire equator line CL as a boundary in a cross-sectional view in the tire meridian direction when the vehicle is mounted, and two or three profiles having different profiles in each tread region A straight line 1 is drawn in the vehicle width direction from the point A on the tire equator line CL, and the profile arc on the outermost side in the tire width direction and the profile arc on the shoulder portion of the tread region on the inner side in the vehicle width direction When the intersection point is a point B and when a straight line m connecting the point B and the point A is drawn, the angle θ formed by the straight line l and the straight line m is 8 [deg] ≦ θ ≦ 10 [ deg] and the groove wall angle α of the groove wall on the outer side in the vehicle width direction and the groove wall angle β of the groove wall on the inner side in the vehicle width direction are α < When the groove wall angles α, β of the plurality of circumferential main grooves are α1, β1, α2, β2, α3, β3,... sequentially from the outer side in the vehicle width direction. The wall angles α and β have a relationship of α1 ≧ α2 ≧ α3 ≧... And β1 ≧ β2 ≧ β3 ≧ .

In this pneumatic tire, the drop angle θ of the tread profile in the tread region on the inner side (IN side) in the vehicle width direction is optimized, so that the tire contact shape is rounded during cornering, and the tire contact pressure distribution is It is made uniform. Thereby, there is an advantage that the grip performance (limit performance) on the dry road surface and the wet performance are improved.
In this pneumatic tire, the groove wall angle α of the groove wall on the outer side in the vehicle width direction and the groove wall angle β of the groove wall on the inner side in the vehicle width direction have a relationship of α <β. Since the rigidity of the land portion on the inner side in the vehicle width direction when viewed from the groove is increased, wear of the edge portion of the land portion is reduced during cornering. Thereby, there is an advantage that wear of land portions constituting both groove walls of the circumferential main groove is made uniform, and uneven wear resistance performance of the tire is improved.
Further, in this pneumatic tire, the groove wall angles α and β of the circumferential main groove are in the range of 15 [deg] ≦ α ≦ 35 [deg] and 20 [deg] ≦ β ≦ 50 [deg]. Since the ranges of the groove wall angles α and β of the circumferential main groove are optimized, there is an advantage that the uneven wear resistance performance of the tire is more effectively improved. In addition, there is an advantage that the grip performance on the dry road surface is improved.
Further, in this pneumatic tire, the groove wall angles α and β of the plurality of circumferential main grooves have the relationship of α1 ≧ α2 ≧ α3 ≧... And β1 ≧ β2 ≧ β3 ≧. Since the groove volume of the circumferential main groove in the region is ensured, there is an advantage that the wet performance of the tire is properly maintained.

  The pneumatic tire according to the present invention has a point C at a position of 40 [%] of the distance TW in the tire width direction from the tire equator line CL to the point B in a sectional view in the tire meridian direction when the vehicle is mounted. The distance L in the tire radial direction from the point A to the point B and the distance L ′ in the tire radial direction from the point A to the point C have a relationship of 0.05 ≦ L ′ / L ≦ 0.15. Have.

  In this pneumatic tire, since the inclination of the tread profile in the tread region on the IN side is made more appropriate, the tire contact pressure distribution during cornering is made more uniform. Thereby, there is an advantage that the grip performance and the wet performance on the dry road surface are further improved.

  In the pneumatic tire according to the present invention, the intersection of the adjacent profile arcs is arranged on the land portion.

  In this pneumatic tire, since the ground contact pressure of the land portion sandwiching the circumferential main groove is made uniform, uneven wear occurring at the edge portion of the land portion is reduced. Thereby, there exists an advantage which the uneven wear-proof performance of a tire improves.

  In the pneumatic tire according to the present invention, the block-shaped land portion defined by the circumferential main groove and a plurality of width-direction grooves extending in the tire width direction is disposed in the tread shoulder region. Sometimes, the arrangement interval of the width direction grooves arranged in the land portion outside the vehicle width direction is larger than the arrangement interval of the width direction grooves arranged in the land portion inside the vehicle width direction.

  In this pneumatic tire, the rigidity of the tread region on the outer side in the vehicle width direction is higher than that on the tread region on the inner side in the vehicle width direction. Thereby, there is an advantage that the effect of suppressing the uneven wear due to the groove wall angles α and β of the circumferential main groove described above is enhanced.

  Further, in the pneumatic tire according to the present invention, the land portion in the tread portion shoulder region on the inner side in the vehicle width direction is partitioned by the circumferential main groove, and the land portion in the tread portion shoulder region on the outer side in the vehicle width direction. The section extends in the tire circumferential direction and is partitioned by a circumferential narrow groove that is narrower than the circumferential main groove.

  In this pneumatic tire, the drainage performance in the tread region on the outer side in the vehicle width direction is improved by the arrangement of the circumferential narrow grooves. Thereby, there exists an advantage by which the wet performance of a tire is ensured. Further, the rigidity of the shoulder land portion is increased as compared with the configuration in which the shoulder land portion is partitioned by the circumferential main groove (not the circumferential narrow groove). Thereby, there exists an advantage which the grip performance of the tire at the time of cornering improves.

  The pneumatic tire according to the present invention has a maximum tire width of 200 [mm] or more.

  In general, in a wide performance tire, it is difficult to achieve both grip performance and wet performance of the tire. Therefore, when the configuration of the pneumatic tire described above is applied to such a tire, there is an advantage that the effect relating to the compatibility between the grip performance and the wet performance of the tire can be obtained more remarkably.

  In the pneumatic tire according to the present invention, the flatness is 55 [%] or less.

  In general, in a low-flat performance tire, it is difficult to achieve both grip performance and wet performance of the tire. Therefore, when the configuration of the pneumatic tire described above is applied to such a tire, there is an advantage that the effect relating to the compatibility between the grip performance and the wet performance of the tire can be obtained more remarkably.

  In the pneumatic tire according to the present invention, since the drop angle θ of the tread profile in the tread region on the inner side (IN side) in the vehicle width direction is optimized, the ground contact shape of the tire is rounded during cornering, so that the tire ground contact is achieved. The pressure distribution is made uniform. Thereby, there is an advantage that the grip performance (limit performance) on the dry road surface and the wet performance are improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a front view showing a pneumatic tire according to an embodiment of the present invention. 2 and 3 are explanatory views showing a profile of the pneumatic tire shown in FIG. FIG. 4 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 5 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

[Pneumatic tire]
The pneumatic tire 1 includes a plurality of circumferential grooves 21 to 24 extending in the tire circumferential direction, a plurality of width direction grooves 31 to 34 extending in the tire width direction, and the grooves 21 to 24, 31 to 31. The tread portion has a plurality of land portions 41 to 43 defined by 24 (see FIG. 1). Further, the circumferential grooves 21 to 24 are constituted by a plurality of circumferential main grooves 21 and 22 and a plurality of circumferential narrow grooves 23 and 24.

  For example, in this embodiment, the tread portion has a tire equator line CL as a boundary, and the tread region on the IN side (region inside the vehicle width direction when the vehicle is mounted) and the tread region on the OUT side (outside in the vehicle width direction when the vehicle is mounted). Area). Two circumferential main grooves 21 and 22 are arranged in the tread region on the IN side, and one circumferential main groove 21 and one circumferential narrow groove 23 are arranged in the tread region on the OUT side. . Further, one circumferential narrow groove 24 is disposed on the tire equator line CL. In the tread region on the IN side, a rib-shaped center land portion 41 is defined by the circumferential narrow groove 24 and the circumferential main groove 21 on the tire equator line CL. Further, a block-shaped second land portion 42 is partitioned by the pair of circumferential main grooves 21 and 22 and the plurality of width direction grooves 31. Further, a block-shaped shoulder land portion 43 is formed by the circumferential main groove 22 on the outer side in the tire width direction and the plurality of width direction grooves 32. On the other hand, in the tread region on the OUT side, a rib-shaped center land portion 41 is defined by the circumferential narrow groove 24 and the circumferential main groove 21 on the tire equator line CL. A block-shaped second land portion 42 is partitioned by the direction narrow groove 23 and the plurality of width direction grooves 31. Further, the circumferential narrow groove 24 and the width direction groove 34 form a block-shaped shoulder land portion 43. As a result, an asymmetric tread pattern based on the block rows 42 and 43 is formed.

  The circumferential main grooves 21 and 22 have a groove width of 8 [mm] or more. Further, the circumferential narrow grooves 23 and 24 have a narrower groove width than this groove width. In this embodiment, as described above, the circumferential narrow groove 23 is disposed in the tread region on the OUT side. However, the circumferential narrow groove 23 is not limited to this, and the circumferential main groove has a wide groove width. May be replaced (not shown).

[Tread Profile]
Moreover, in this pneumatic tire 1, the profile of each tread region is composed of two or three profile arcs that are different from each other in a sectional view in the tire meridian direction when the vehicle is mounted (see FIG. 1). For example, in this embodiment, the profile of the tread region on the IN side and the profile of the tread region on the OUT side are each constituted by three profile arcs L1 to L3 (three-stage radius structure). These profile arcs L1 to L3 have different radii of curvature.

  Here, a straight line 1 is drawn in the vehicle width direction from the point A on the tire equator line CL. Further, an intersection of the profile arc L3 that is the outermost in the tire width direction in the IN-side tread region and the profile arc of the shoulder portion is defined as a point B. Further, a straight line m connecting the point B and the point A is drawn. At this time, the angle θ formed by the straight line l and the straight line m is in the range of 8 [deg] ≦ θ ≦ 10 [deg]. That is, the depression angle θ of the tread profile is optimized.

  In addition, the sagging angle θ refers to an angle θ formed by the straight line l and the straight line m when the tire is attached to the applicable rim and applied with a specified internal pressure and is in a no-load state.

  Here, the applicable rim means “applied rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. The normal internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO. However, in the case of a tire for a passenger car, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

[effect]
In this pneumatic tire 1, the tread profile sagging angle θ in the tread region on the inner side (IN side) in the vehicle width direction is optimized, so that the tire ground contact shape is rounded during cornering, and the tire ground pressure distribution Is made uniform. Thereby, there is an advantage that the grip performance (limit performance) on the dry road surface and the wet performance are improved.

[Additional matter 1]
In the pneumatic tire 1, when a point C is taken at a position of 40 [%] of the distance TW in the tire width direction from the tire equator line CL to the point B in a sectional view in the tire meridian direction when the vehicle is mounted. Further, the distance L in the tire radial direction from the point A to the point B and the distance L ′ in the tire radial direction from the point A to the point C have a relationship of 0.05 ≦ L ′ / L ≦ 0.15. Is preferred (see FIG. 3). In such a configuration, since the inclination of the tread profile in the tread region on the IN side is made more appropriate, the tire contact pressure distribution during cornering is made more uniform. Thereby, there is an advantage that the grip performance and the wet performance on the dry road surface are further improved.

[Additional matter 2]
In this pneumatic tire 1, it is preferable that the intersection (the inflection point of the tread profile) of the adjacent profile arcs L1, L2 (L2, L3) is disposed on the land portion 42 (43) (see FIG. 2). ). That is, it is preferable that the circumferential main grooves 21 and 22 are disposed in any one of the profile arcs L1 to L3. In such a configuration, since the ground contact pressure of the land portions 41 and 42 (42, 43) sandwiching the circumferential main groove 21 (22) is made uniform, uneven wear generated at the edge portions of the land portions 41 to 43 is reduced. The Thereby, there exists an advantage which the uneven wear-proof performance of a tire improves.

  For example, in this embodiment, the left and right tread regions have three profile arcs L1 to L3, respectively, and these profile arcs L1 to L3 are arranged symmetrically about the tire equator line CL. (See FIG. 2). Further, in each tread region, the intersection of profile arcs L1 and L2 inside the tire width direction is arranged on the second land portion 42, and the intersection of profile arcs L2 and L3 outside the tire width direction is the shoulder land. It is arranged on the part 43.

  However, the present invention is not limited to this, and the intersections of the adjacent profile arcs L1 to L3 may be arranged in the circumferential main grooves 21 and 22 (see FIG. 4). Such a configuration also has the advantage of improving tire grip performance and wet performance.

  For example, in the configuration shown in FIG. 4, compared to the configuration shown in FIG. 2, the intersection of the profile arcs L1 and L2 on the inner side in the tire width direction is arranged in the circumferential main groove 21 on the inner side in the tire width direction. Further, the difference is that the intersection of the profile arcs L2 and L3 on the outer side in the tire width direction is arranged in the circumferential main groove 22 (circumferential narrow groove 23) on the outer side in the tire width direction.

[Additional matter 3]
Moreover, in this pneumatic tire 1, the groove wall angle α of the groove wall on the outer side in the vehicle width direction of both the groove walls of the circumferential main groove 21 (22) in a cross-sectional view in the tire meridian direction when the vehicle is mounted. It is preferable that the groove wall angle β of the groove wall on the inner side in the vehicle width direction has a relationship of α <β (see FIG. 3). In such a configuration, the rigidity of the land portion 42 (43) located on the inner side in the vehicle width direction as viewed from the circumferential main groove 21 (22) is enhanced, so that the edge portion of the land portion 42 (43) is worn during cornering. Is reduced. Thereby, the wear of the land portions 41, 42 (42, 43) constituting both groove walls of the circumferential main groove 21 (22) is made uniform, and there is an advantage that the uneven wear resistance performance of the tire is improved. For example, in a configuration in which both groove walls of the circumferential main groove have the same groove wall angle (not shown), the edge portion of the land portion on the inner side in the vehicle width direction when viewed from the circumferential main groove is the land on the outer side in the vehicle width direction. Since it is easier to wear than the part, uneven wear tends to occur.

  In the above configuration, the groove wall angles α and β of the circumferential main grooves 21 and 22 are in the range of 15 [deg] ≦ α ≦ 35 [deg] and 20 [deg] ≦ β ≦ 50 [deg]. It is preferable (see FIG. 3). In such a configuration, since the ranges of the groove wall angles α and β of the circumferential main grooves 21 and 22 are optimized, there is an advantage that the uneven wear resistance performance of the tire is more effectively improved. In addition, there is an advantage that the grip performance on the dry road surface is improved.

  Further, in the above configuration, when the groove wall angles α and β of the plurality of circumferential main grooves 21 and 22 are α1, β1, α2, β2, α3, β3,. It is preferable that the wall angles α and β have a relationship of α1 ≧ α2 ≧ α3 ≧... And β1 ≧ β2 ≧ β3 ≧. That is, the groove wall angles α and β of the plurality of circumferential main grooves 21 and 22 are set so as to decrease from the outer side in the vehicle width direction toward the inner side in the vehicle width direction. In such a configuration, since the groove volumes of the circumferential main grooves 21 and 22 in the tread region on the inner side in the vehicle width direction are ensured, there is an advantage that the wet performance of the tire is properly maintained.

[Additional matter 4]
Moreover, in this pneumatic tire 1, the block-shaped land parts 42 and 43 divided by the circumferential main grooves 21 and 22 and the some width direction groove | channels 31-34 extended in a tire width direction are tread part shoulders. When arranged in the area, the arrangement interval of the width direction grooves 33 and 34 arranged in the land portions 42 and 43 on the outer side in the vehicle width direction is the width direction groove 31 arranged in the land portions 42 and 43 on the inner side in the vehicle width direction. , 32 is preferably larger (see FIG. 1). That is, a larger block row than the tread region on the inner side in the vehicle width direction is arranged in the tread region (tread portion shoulder region) on the outer side in the vehicle width direction. In such a configuration, the rigidity of the tread region on the outer side in the vehicle width direction is higher than that of the tread region on the inner side in the vehicle width direction. Accordingly, there is an advantage that the effect of suppressing the uneven wear due to the groove wall angles α and β of the circumferential main grooves 21 and 22 is enhanced.

  For example, in this embodiment, the arrangement interval of the width direction grooves 33 and 34 in the tread region (shoulder land portion 43) on the outer side in the vehicle width direction is equal to the arrangement interval of the width direction grooves 33 and 34 in the tread region on the inner side in the vehicle width direction. It is set to about twice (see FIG. 1). Thereby, the rigidity (area) of the shoulder land portion 43 on the outer side in the vehicle width direction is set larger than that on the shoulder land portion 43 on the inner side in the vehicle width direction.

  Further, in the pneumatic tire 1, the land portion (shoulder land portion) 43 in the tread portion shoulder region on the inner side in the vehicle width direction is partitioned by the circumferential main groove 22, and in the tread portion shoulder region on the outer side in the vehicle width direction. It is preferable that a certain land portion 43 extends in the tire circumferential direction and is partitioned by a circumferential narrow groove 23 that is narrower than the circumferential main groove 22 (see FIG. 1). That is, the shoulder land portion 43 is defined by the circumferential narrow groove 23 in the tread region on the outer side in the vehicle width direction. In such a configuration, the drainage performance in the tread region on the outer side in the vehicle width direction is improved by the arrangement of the circumferential narrow grooves 23. Thereby, there exists an advantage by which the wet performance of a tire is ensured. Further, the rigidity of the shoulder land portion is increased as compared with the configuration in which the shoulder land portion is partitioned by the circumferential main groove (not the circumferential narrow groove 23). Thereby, there exists an advantage which the grip performance of the tire at the time of cornering improves.

  For example, in this embodiment, two circumferential main grooves 21 and 22 are disposed in the tread region on the inner side in the vehicle width direction, and one circumferential main groove 21 is disposed on the tread region on the outer side in the vehicle width direction. One circumferential narrow groove 23 is disposed (see FIG. 1). Further, the circumferential grooves 21, 22; 21, 23 arranged in each shoulder region are arranged symmetrically about the tire equator line CL. Further, in the tread region on the inner side in the vehicle width direction, the shoulder land portion 43 is partitioned by the circumferential main groove 22, and in the tread region on the outer side in the vehicle width direction, the shoulder land portion 43 is partitioned by the circumferential narrow groove 23. Yes. Therefore, the rigidity (area) of the shoulder land portion 43 on the outer side in the vehicle width direction is set larger than that on the shoulder land portion 43 on the inner side in the vehicle width direction.

  In this embodiment, as described above, the tread profile is configured asymmetrically around the tire equator line CL (asymmetric profile) (see FIG. 1). However, the present invention is not limited to this, and the tread profile may be configured symmetrically about the tire equator line CL (symmetric profile) (not shown).

[Application example]
Moreover, in this pneumatic tire, it is preferable that the tire maximum width is 200 [mm] or more. In general, in a wide performance tire, it is difficult to achieve both grip performance and wet performance of the tire. Therefore, when the configuration of the pneumatic tire 1 is applied to such a tire, there is an advantage that the effect relating to the compatibility between the grip performance and the wet performance of the tire can be obtained more remarkably.

  Moreover, in this pneumatic tire 1, it is preferable that an aspect ratio is 55 [%] or less. In general, in a low-flat performance tire, it is difficult to achieve both grip performance and wet performance of the tire. Therefore, when the configuration of the pneumatic tire 1 is applied to such a tire, there is an advantage that the effect relating to the compatibility between the grip performance and the wet performance of the tire can be obtained more remarkably.

[performance test]
In this example, performance tests on (1) grip performance on a dry road surface, (2) wet performance, and (3) uneven wear resistance performance were performed on a plurality of pneumatic tires having different conditions (see FIG. 5). . In this performance test, a pneumatic tire having a tire size of 245 / 40R18 is assembled to a rim having a rim size of 18 × 8.5 JJ, and an internal pressure of 220 [kPa] and a load prescribed by JATMA are applied to the pneumatic tire. This pneumatic tire is mounted on a test vehicle equipped with an engine with a displacement of 2000 [cc].

  (1) In the performance test regarding grip performance on a dry road surface, a test vehicle goes around a dry road test course, and a test driver performs sensory evaluation on tire grip performance. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  (2) In the performance test related to the wet performance, the hydroplaning cornering method is used for evaluation. Specifically, the running speed of the test vehicle when the test vehicle runs on a test course with a water depth of 10 ± 1 [mm] and a turning radius of 100 R and the maximum lateral acceleration of the test tire is generated is recorded as the hydroplaning generation speed. The Based on this, index evaluation is performed using the conventional example as a reference (100). An evaluation result is so preferable that the numerical value is large.

  (3) In the performance test relating to uneven wear resistance, the test vehicle travels 8000 [km] on the test course, and uneven wear occurring in the center land portion and the shoulder land portion after the travel is observed. Then, based on the observation result, index evaluation using the conventional example as a reference (100) is performed. An evaluation result is so preferable that the numerical value is large.

  The conventional pneumatic tire is configured by three profile arcs L1 to L3 in which the profiles of the tread regions on the left and right sides of the tire are different from each other in a sectional view in the tire meridian direction when the vehicle is mounted. Two circumferential main grooves are disposed in the tread region on the inner side in the vehicle width direction, and one circumferential main groove and one circumferential narrow groove are disposed in the tread region on the outer side in the vehicle width direction. Each is arranged. Further, the intersections of adjacent profile arcs L1 to L3 are arranged in the circumferential main groove. In addition, the sagging angle θ of the profile on the inner side (IN side) in the vehicle width direction is set in the range of 5 [deg] to 6 [deg].

  On the other hand, in the pneumatic tires 1 of Invention Examples 1 to 6, the sagging angle θ of the profile on the inner side in the vehicle width direction is set to 9 [deg] (see FIG. 1). Moreover, in the pneumatic tire 1 of the invention example 1, the intersection of the adjacent profile circular arcs L1-L3 is arrange | positioned in the circumferential direction main grooves 21 and 22. FIG. On the other hand, in the pneumatic tires 1 of Invention Examples 2 to 6, the intersections of the adjacent profile arcs L1 and L2 (L2, L3) are arranged on the land portion 42 (43).

  As shown in the test results, it can be seen that in the pneumatic tires 1 of Invention Examples 1 to 6, the tire grip performance and wet performance are improved (see FIG. 5). Further, when Invention Example 1 and Invention Example 2 are compared, the intersection of adjacent profile arcs L1 and L2 (L2, L3) is arranged on the land portion 42 (43), thereby further improving uneven wear resistance. It turns out that it improves. Further, when Invention Example 2 and Invention Example 3 are compared, the relationship between the groove wall angles α and β of the circumferential main grooves 21 and 22 is optimized (α <β), thereby maintaining the wet performance of the tire. However, it can be seen that the dry performance and uneven wear resistance of the tire are improved. Further, when Invention Example 3 and Invention Example 4 are compared, the range of the groove wall angles α and β of the circumferential main grooves 21 and 22 is optimized, so that the dry performance and uneven wear resistance of the tire are further improved. I understand that Further, when Invention Example 3 and Invention Example 5 are compared, the size relationship of the groove wall angles α1, β1, α2, β2, α3, β3 of the circumferential main grooves 21, 22 is optimized, so that the tire It can be seen that dry performance and uneven wear resistance are further improved. In addition, when Invention Example 2 and Invention Example 6 are compared, the ratio L ′ / L between the distance L and the distance L ′ is optimized, which further improves the dry performance and uneven wear resistance performance of the tire. I understand.

  As described above, the pneumatic tire according to the present invention is useful in that it can improve grip performance and wet performance on a dry road surface.

1 is a front view showing a pneumatic tire according to an embodiment of the present invention. It is explanatory drawing which shows the profile of the pneumatic tire described in FIG. It is explanatory drawing which shows the profile of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 21, 22 Circumferential main groove 23, 24 Circumferential narrow groove 31-34 Width direction groove 41 Center land part 42 Second land part 43 Shoulder land part

Claims (8)

A pneumatic tire having a plurality of circumferential main grooves extending in the tire circumferential direction and land portions defined by these circumferential main grooves in a tread portion,
From a cross-sectional view in the tire meridian direction when the vehicle is mounted, the tread portion is divided into two tread regions with the tire equator line CL as a boundary, and the profiles of each tread region are different from two or three profile arcs that are different from each other. growth is,
A straight line 1 is drawn from the point A on the tire equator line CL in the vehicle width direction, and the intersection point between the profile arc on the outermost side in the tire width direction and the profile arc on the shoulder portion in the tread region on the inner side in the vehicle width direction is point B. with a, when drawing a straight line m connecting the this point B and the point a, Ri range near the angle between the line l and the line m theta is 8 [deg] ≦ θ ≦ 10 [deg],
Of the groove walls of the circumferential main groove, the groove wall angle α of the groove wall on the outer side in the vehicle width direction and the groove wall angle β of the groove wall on the inner side in the vehicle width direction have a relationship of α <β, and ,
A pneumatic tire characterized in that the groove wall angles α and β of the circumferential main groove are in a range of 15 [deg] ≦ α ≦ 35 [deg] and 20 [deg] ≦ β ≦ 50 [deg] . A pneumatic tire having a plurality of circumferential main grooves extending in the tire circumferential direction and land portions defined by these circumferential main grooves in a tread portion,
From a cross-sectional view in the tire meridian direction when the vehicle is mounted, the tread portion is divided into two tread regions with the tire equator line CL as a boundary, and the profiles of each tread region are different from two or three profile arcs that are different from each other. growth is,
A straight line 1 is drawn from the point A on the tire equator line CL in the vehicle width direction, and the intersection point between the profile arc on the outermost side in the tire width direction and the profile arc on the shoulder portion in the tread region on the inner side in the vehicle width direction is point B. with a, when drawing a straight line m connecting the this point B and the point a, Ri range near the angle between the line l and the line m theta is 8 [deg] ≦ θ ≦ 10 [deg],
Of the groove walls of the circumferential main groove, the groove wall angle α of the groove wall on the outer side in the vehicle width direction and the groove wall angle β of the groove wall on the inner side in the vehicle width direction have a relationship of α <β, and ,
When the groove wall angles α, β of the plurality of circumferential main grooves are α1, β1, α2, β2, α3, β3,... In order from the outside in the vehicle width direction, these groove wall angles α, β are α1 ≧ α2. A pneumatic tire having a relationship of ≧ α3 ≧... And β1 ≧ β2 ≧ β3 ≧ . When the point C is located at a position 40% of the distance TW in the tire width direction from the tire equator line CL to the point B in a cross-sectional view in the tire meridian direction when the vehicle is mounted, from the point A to the point B The pneumatic according to claim 1 or 2 , wherein the distance L in the tire radial direction and the distance L 'in the tire radial direction from the point A to the point C have a relationship of 0.05≤L' / L≤0.15. tire. The pneumatic tire according to any one of claims 1 to 3 , wherein an intersection of adjacent profile arcs is disposed on the land portion. When the block-shaped land portion defined by the circumferential main groove and a plurality of width-direction grooves extending in the tire width direction is disposed in the tread portion shoulder region, the land portion on the outer side in the vehicle width direction The pneumatic tire according to any one of claims 1 to 4 , wherein an arrangement interval of the width direction grooves arranged in the vehicle is larger than an arrangement interval of the width direction grooves arranged in the land portion on the inner side in the vehicle width direction. . The land portion in the tread portion shoulder region on the inner side in the vehicle width direction is partitioned by the circumferential main groove, and the land portion in the tread portion shoulder region on the outer side in the vehicle width direction extends in the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 5 , wherein the pneumatic tire is defined by a circumferential narrow groove that is narrower than the circumferential main groove. The pneumatic tire according to any one of claims 1 to 6 , wherein the maximum tire width is 200 mm or more. The pneumatic tire according to any one of claims 1 to 7 , wherein the flatness is 55 [%] or less.

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