JP2006160154A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing the dry gripping performance and the anti-abrasiveness while the tire can exert the resistance against hydroplaning in driving and at braking in such a way as well balanced and to a high grade of performance. <P>SOLUTION: In lieu of longitudinal main grooves, slant main grooves 9 are provided including a straight slope part 10 inclining in straight form. The ratio Ss/Sc of the sea area ratio Sc of the central region to the sea area ratio Ss of the shoulder region Ys is made 70-90%. The angle θ of the slant main groove 9 to the circumferential direction should range between 0-70° in the central region Yc, particularly 35-70° in its straight slope part 10, and 0-90° in each shoulder part Ys, particularly 50-90° in its straight sloe part 10. The shoulder region Yso on the outside about the vehicle does not include a convex circular arc part 11 which is convex to outside the vehicle and where the angle θ becomes 10° or less. The ratio Sr/Sf of the sum total Sf of the groove areas of the rotating direction inclining part 9f among the slant main grooves 9 to the sum total Sr of the groove areas of the non-rotating direction slant part 9r is made 90-150%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention can exhibit high dry grip performance and wear resistance performance during race running such as circuit competitions and gymkhana competitions while sufficiently ensuring excellent wet grip performance (hydroplaning performance) especially on public road running. Related to pneumatic tires.

  As shown in Fig. 7 (A), S-shaped mainly intended to improve dry grip performance as a tread pattern for high-performance tires on the premise of racing on circuit roads and gymkhana competitions in addition to running on public roads. As shown in FIG. 7B, a V-shaped pattern that improves both wet grip performance and dry grip performance is widely used (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-127715 (FIGS. 2 and 8)

  However, in the S-shaped pattern, although the rigidity of the entire block with respect to the lateral acceleration (lateral G) is high, the curved portion in which the S-shaped groove a is curved is convex toward the outside of the vehicle, particularly when the vehicle is mounted. In the convex curve part p1 which becomes, wear tends to advance early. In particular, this wear occurs remarkably in the convex curved portion p1s located in the shoulder region Ys outside the vehicle.

  On the other hand, the V-shaped pattern has good anti-hydroplaning performance, but is particularly suitable for a tread on the outside of the vehicle when racing on a road surface having a high friction coefficient μ, such as a competition course, at a high lateral G. The lateral rigidity in the half portion to is not sufficient, and it is difficult to further shorten the running time by blending the tread rubber and changing the structure. Further, in the V-shaped groove b, in the tread half portion to the vehicle outer side, there is a problem that wear progresses quickly in the groove portion b1 having an angle θ with respect to the circumferential direction of 35 ° or less. Furthermore, since the V-shaped groove b has directionality, for example, the anti-hydroplaning performance at the time of driving is good, but there is a strong tendency to become unbalanced, for example, the anti-hydroplaning performance at the time of braking is insufficient.

  Accordingly, an object of the present invention is to provide a pneumatic tire capable of further improving the dry grip performance and the wear resistance while exhibiting a balanced and high hydroplaning resistance during driving and braking. .

In order to achieve the above object, the invention according to claim 1 of the present application is that the tread portion does not have a longitudinal main groove extending substantially continuously in the circumferential direction, and is linearly inclined with respect to the circumferential direction. A pneumatic tire provided with an inclined main groove including
The tread portion has a ratio Ss / Sc between the sea area ratio Sc of the tread pattern in the central region of 50% of the tread width centered on the tire equator and the sea area ratio Ss of the tread pattern in the shoulder region on both outer sides thereof. 70-90%
The inclined main groove has an angle with respect to the circumferential direction in the central region in the range of 0 to 70 °, and in the linear inclined portion in a range of 35 to 70 °, and in the shoulder region, the angle with respect to the circumferential direction. In the range of 0 to 90 ° and in the linear inclined portion, the range of 50 to 90 °,
The inclined main groove does not include a convex arc portion that is convex toward the vehicle outer side and has an angle of 10 ° or less with respect to the circumferential direction in the outer shoulder region that faces the vehicle outer side when the vehicle is mounted.
In addition, among the inclined main grooves, the total groove area Sf of the rotation direction inclined portions inclined in the tire rotation direction from the tire equator toward the tread end, and the total groove area of the non-rotation direction inclination portions inclined in the non-rotation direction. The ratio Sr / Sf to Sr is 90 to 150%.

  According to a second aspect of the present invention, the inclined main groove is a convex arc that is convex toward the vehicle outer side and has an angle with respect to the circumferential direction of 10 ° or less in an outer central region of the central region facing the vehicle outer side. It is characterized by not including parts.

  The “tread width” refers to the width in the tire axial direction between the tread grounding ends when a normal load is applied to a tire with a normal rim assembled and filled with a normal internal pressure and a normal load is applied to a flat surface. Means. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO means "Measuring Rim". The “regular internal pressure” is the air pressure specified by the tire for each tire. The maximum air pressure in the case of JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, In the case of ETRTO, it means “INFLATION PRESSURE”, but in the case of passenger tires, it is 180 kPa. The “regular load” is the load specified by the standard for each tire. The maximum load capacity shown in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is the maximum load capacity for JATMA and TRA for TRA. In the case of ETRTO, it means a load obtained by multiplying "LOAD CAPACITY" by 0.88.

  Since the present invention is configured as described above, it is possible to further improve the dry grip performance and the wear resistance while exhibiting a high and well-balanced hydroplaning resistance during driving and braking.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a meridional section of the pneumatic tire of the present invention, and FIG. 2 shows its tread pattern.
In FIG. 1, a pneumatic tire 1 is a high-performance tire that is premised on both public road driving and race driving such as circuit competitions and gymkhana competitions, and the bead portion extends from the tread portion 2 to the sidewall portion 3. A carcass 6 having a radial structure leading to four bead cores 5 is provided.

  A belt layer 7 is wound on the outside of the carcass 6 and on the inside of the tread portion 2, and the flatness ratio H / W, which is the ratio of the tire cross-section height H and the tire width W, is obtained by the tagging effect. In this example, it is restrained to 50% or less, for example, 40%. As a result, the tire rigidity is increased, while a wide tread width TW is ensured to improve high-speed performance and steering stability.

  Further, as shown in FIG. 2, the tread portion 2 does not have a vertical main groove extending substantially continuously in the circumferential direction, and is substantially composed of a plurality of inclined main grooves 9 that are inclined with respect to the circumferential direction. A horizontal V-shaped tread pattern is formed. In FIG. 2, the outer tread grounding end Eo that is the outer side of the vehicle when mounted on the vehicle is illustrated on the right side, and the inner tread grounding end Ei that is on the inner side of the vehicle is directed to the left side. A 50% width of the tread width TW centering on the tire equator C is illustrated as a central region Yc, and both outer sides thereof are illustrated as a shoulder region Ys.

  In the present embodiment, the inclined main groove 9 includes a linearly inclined portion 10 that is linearly inclined with respect to the circumferential direction. In the central region Yc, the angle θ with respect to the circumferential direction is in the range of 0 to 70 °. In the said linear inclination part 10, it is set as the range of 35-70 degrees. In the shoulder region Ys, the angle θ with respect to the circumferential direction is in the range of 0 to 90 °, and the linear inclined portion 10 is in the range of 50 to 90 °. Further, the inclined main groove 9 has a convex arc portion 11 that is convex toward the vehicle outer side and has an angle θ with respect to the tire circumferential direction of 10 ° or less in the outer shoulder region Yso that faces the vehicle outer side when the vehicle is mounted. Constructed without including.

  The angle θ is an angle with respect to the circumferential direction of the groove center line of the inclined main groove 9, and when the groove center line is a curve, it means an angle with respect to the circumferential direction of the tangent line.

Next, the inclined main groove 9 will be specifically described. In this example, the inclined main groove 9 is
(1) It has an arcuate apex 20 in the vicinity of the tire equator C, and is inclined from the apex 20 toward the inner tread ground contact Ei toward the rotation direction F and the non-rotation direction R of the tire, respectively. A substantially horizontal V-shaped first inclined main groove 9A provided with a pair of extending inclined portions 21f, 21r. (2) Adjacent to the first inclined main groove 9A on the tread grounding end Ei side. A substantially inclined V-shaped second inclined main groove 9B,
(3) Adjacent to the first inclined main groove 9A on the non-rotating direction R side, and inclined in the non-rotating direction R from the outer tread grounding end Eo side toward the inner tread grounding end Ei side. The third inclined main groove 9C extending,
(4) The first inclined main groove 9A is a fourth inclined main groove 9D having a substantially line symmetrical shape with the tire equator C as the center,
(5) The second inclined main groove 9B is a fifth inclined main groove 9E having a substantially line-symmetric shape with the tire equator C as the center, and (6) the third inclined main groove 9C. A sixth inclined main groove 9F having a substantially line-symmetric shape around the tire equator C;
The case where it comprises from is illustrated.

  The fourth to sixth inclined main grooves 9D to 9F have a circumferential pitch P (pattern pitch P) of the pattern constituent unit of the tread pattern with respect to the first to third inclined main grooves 9A to 9C, respectively. 1/2 is displaced in the tire circumferential direction. The inclined main grooves 9A to 9F do not intersect with each other, and have one end closed in the tread ground surface and the other end opened as a tread ground end Ei or Eo. It is preferable from the viewpoint of pattern rigidity and wet grip performance.

  As shown in FIG. 3, in the first inclined main groove 9A, the top portion 20 forms a semicircular arc-shaped convex arc portion 11 that protrudes toward the vehicle outer side, and the outer side that faces the vehicle outer side when mounted on the vehicle. In the central region Yco. The angle θ in the convex arc portion 11 is in the range of 0 to 70 °, preferably 0 to 35 °, and is 0 ° at the convex point position Q that is most convex toward the outside of the vehicle.

  The one and other inclined portions 21f and 21r include linear inclined portions 10a and 10b extending linearly toward the rotation direction F side and the non-rotation direction R side, respectively, toward the inner tread ground end Ei. . For example, one linear inclined portion 10a is provided with a curved portion 12 that is curved and extends in an arc shape while increasing the angle θ to the inner tread grounding end Ei. The angle θ of each of the linear inclined portions 10a and 10b is 50 to 70 ° (for example, 60 °) in this example, and extends beyond the inner central region Yci to the inner shoulder region Ysi. .

  Accordingly, in the first inclined main groove 9A, in the central region Yc, the angle θ with respect to the circumferential direction is in the range of 0 to 70 °, and in the linear inclined portions 10a and 10b, the angle θ is 50 to 70 °. (For example, 60 °) and within a range of 35 to 70 °. In the shoulder region Ys, the angle θ is 50 ° or more and in the range of 0 to 90 °, and in the linear inclined portions 10a and 10b, the angle θ is 50 to 70 ° (for example, 60 °) and 50. It is set within a range of ˜90 °.

  Next, the second inclined main groove 9B has substantially the same configuration as the first inclined main groove 9A, and has a top portion 22 in the vicinity of the boundary line between the central region Yci and the shoulder region Ysi, and the top portion 22 is formed in a substantially lateral V-shape having a pair of inclined portions 23f and 23r that incline toward the inner tread contact edge Ei toward the rotation direction F and the non-rotation direction R of the tire. The top portion 22 also forms a semicircular arc-shaped convex arc portion 11 that protrudes toward the vehicle outer side, and the angle θ is set to 0 ° at the convex point position Q.

  The one and other inclined portions 23f and 23r include linear inclined portions 10c and 10d extending linearly toward the rotation direction F side and the non-rotation direction R side, respectively, toward the inner tread ground end Ei. For example, in the other linear inclined portion 10d, a curved portion 12 extending in an arc shape is extended to the inner tread grounding end Ei while increasing the angle θ. In this example, each of the linear inclined portions 10c and 10d has an angle θ with respect to the tire circumferential direction of 50 to 70 °, and is disposed in the inner shoulder region Ysi.

  Accordingly, in the second inclined main groove 9B, only the convex arc portion 11 exists in the central region Yc, and the angle θ is in the range of 0 to 70 °. In the shoulder region Ys, the angle θ is set in the range of 0 ° to 90 ° and 50 ° or more, and the linear inclined portions 10c and 10d are set in the range of 50 ° to 70 ° and 50 ° to 90 °. ing.

  Next, the third inclined main groove 9 </ b> C is formed from an inclined portion 24 that extends in the non-rotating direction R from the outer tread ground end Eo side toward the inner tread ground end Ei side. In this example, the inclined portion 24 includes a linear inclined portion 10e that linearly inclines from one end in the outer shoulder region Yso to the other end in the inner shoulder region Ysi. A curved portion 12 extending in an arc shape is extended to the tread grounding end Ei while increasing the angle θ. In this example, the linear inclined portion 10e also has an angle θ with respect to the tire circumferential direction of 50 to 70 °, and extends the outer shoulder region Yso, the central region Yc, and the inner shoulder region Ysi.

  Accordingly, in the third inclined main groove 9C, only the linear inclined portion 10e exists in the central region Yc, and the angle θ is in the range of 35 to 70 °, such as 50 to 70 °. In the shoulder region Ys, the angle θ is set to 50 ° or more and 0 to 90 °, and the linear inclined portion 10e is set to 50 to 70 ° and 50 to 90 °.

  Further, the fourth inclined main groove 9D and the first inclined main groove 9A have a substantially line-symmetric shape centered on the tire equator C, and as shown in FIG. A pair of inclined portions 31f and 31r extending from the arcuate top portion 30 toward the outer tread contact end Eo toward the rotation direction F and the non-rotation direction R of the tire, respectively. The top portion 30 forms a semicircular arc-shaped concave arc portion 13 that is concave toward the vehicle outer side, and is disposed in the inner central region Yci, and at a concave point position K that is most concave toward the vehicle outer side, The angle θ is set to 0 °. The one and other inclined portions 31f and 31r include linear inclined portions 10f and 10g that linearly incline toward the outer tread grounding end Eo, and the one linear inclined portion 10f includes the outer tread grounding end. A bending portion 14 that increases the angle θ is extended to Eo. The angle θ of each of the linear inclined portions 10f and 10g is also 50 to 70 ° (for example, 60 °) in this example, and extends beyond the outer central region Yco and into the outer shoulder region Yso. . Accordingly, even in the fourth inclined main groove 9D, the angle θ is 0 to 70 ° in the central region Yc, particularly 35 to 70 ° in the linear inclined portions 10f and 10r, and in the shoulder region Ys. The angle θ is in the range of 0 to 90 °, particularly 50 to 90 ° in the linear inclined portions 10f and 10r.

  Further, the fifth inclined main groove 9E and the second inclined main groove 9B have a substantially line-symmetric shape with the tire equator C as the center, and are located in the vicinity of the boundary line between the central region Yco and the shoulder region Yso. A pair of inclined portions 33f and 33r extending from the top portion 32, which inclines toward the outer tread ground end Eo toward the rotation direction F and the non-rotation direction R of the tire, respectively. This top portion 32 also forms a semicircular arc-shaped concave arc portion 13 that is concave toward the vehicle outer side, and is arranged in the outer central region Yco, and at the concave point position K that is most concave toward the vehicle outer side, The angle θ is set to 0 °. The one and other inclined portions 33f and 33r include linear inclined portions 10h and 10i that linearly incline toward the outer tread grounding end Eo, and the other linear inclined portion 10i includes the outer tread grounding end. A bending portion 14 that increases the angle θ is extended to Eo. The angle θ of each of the linear inclined portions 10h and 10i is also 50 to 70 ° in this example, and is arranged in the outer shoulder region Yso. Accordingly, even in the fifth inclined main groove 9E, only the concave arc portion 13 exists in the central region Yc so that the angle θ is in the range of 0 to 70 °, and in the shoulder region Ys, the angle θ Is in the range of 50 to 90 °, particularly in the linear inclined portions 10h and 10i.

  Further, the sixth inclined main groove 9F and the third inclined main groove 9C have a substantially line symmetrical shape with the tire equator C as the center, and the inner tread ground end Ei from the outer tread ground end Eo side. It is formed from an inclined portion 34 that inclines in the rotational direction F toward the side. In this example, the inclined portion 34 includes a linear inclined portion 10j that linearly inclines from one end in the outer shoulder region Yso to the other end in the inner shoulder region Ysi. A curved portion 14 that increases the angle θ extends to the tread grounding end Eo. The angle θ of the linear inclined portion 10j is also 50 to 70 ° in this example, and extends through the outer shoulder region Yso, the central region Yc, and the inner shoulder region Ysi. Accordingly, in the sixth inclined main groove 9F, only the linear inclined portion 10j exists in the central region Yc so that the angle θ is in the range of 35 to 70 °, and in the shoulder region Ys, the angle θ Is in the range of 0 to 90 °, particularly 50 to 90 ° in the linear inclined portion 10j.

  Further, in the inclined main groove 9 of the present example, the first and second inclined main grooves 9A and 9B are formed with a convex arc portion 11 that protrudes toward the vehicle outer side. It is located in the central region Yco and the central region Yci within it. That is, the inclined main groove 9 is formed without including the convex arc portion 11 in the outer shoulder region.

Next, the function and effect of the inclined main groove 9 will be described.
First, the tread pattern of the present embodiment using the inclined main groove 9 does not have the vertical main groove extending continuously in the circumferential direction, so that the pattern lateral rigidity can be sufficiently ensured. Accordingly, high dry grip performance can be exhibited even in race running where a high lateral G acts, and at the same time, circumferential groove edges that cause premature wear can be eliminated, and wear resistance performance can be improved.

  Further, since the linear inclined portion 10 is provided in the inclined main groove 9, the drainage resistance can be minimized. Moreover, in the central region Yc where high drainage is required, the angle θ with respect to the circumferential direction of the linear inclined portion 10 is set to 35 to 70 °, so that a sufficient drainage effect to the front of the tire can be ensured. If the angle θ is less than 35 °, the lateral stiffness of the pattern is reduced and a sufficient lateral grip cannot be obtained, and early wear tends to occur at the groove edge of the linear inclined portion 10. Conversely, when it exceeds 70 °, the drainage effect is reduced and sufficient wet grip performance cannot be obtained. From such a viewpoint, it is preferable that the lower limit value of the angle θ in the central region Yc of the linear inclined portion 10 is 45 ° or more and the upper limit value is 60 ° or less.

  On the other hand, in the shoulder region Ys, there is little contribution to draining water ahead of the tire when wet, and conversely, the contact pressure and lateral force received during cornering on the dry road surface are greater than in the central region Yc. Therefore, in the shoulder region Ys, the pattern lateral rigidity is enhanced by setting the angle θ of the linear inclined portion 10 to 50 ° or more. If it is less than 50 °, the pattern lateral rigidity is insufficient, and the dry grip performance including the lateral grip cannot be exhibited highly. From such a viewpoint, it is preferable that the lower limit value of the angle θ in the shoulder region Ys of the linear inclined portion 10 is 55 ° or more.

  The ground pressure and lateral force received during cornering are highest in the outer shoulder region Yso in the order of Yso> Yco> Yci> Ysi. Therefore, if there is the convex arc portion 11 in the other shoulder region Yso, early wear occurs in the vicinity of the convex point position Q where the angle θ is 10 ° or less, and the wear resistance is remarkably reduced. It becomes a trend. However, in the present embodiment, since the convex arc portion 11 is excluded at least in the outer shoulder region Yso, this kind of early wear can be suppressed.

  In the fifth inclined main groove 9E, there is a concave arc portion 13 that is concave toward the outside of the vehicle in the vicinity of the boundary line between the central region Yco and the shoulder region Yso. In the vicinity of the point position K, the angle θ is 10 ° or less. However, since the concave arc portion 13 forms a substantially horizontal V-shaped apex that spreads toward the outer tread grounding end Eo, the lateral rigidity is larger than that of the convex arc portion 11, and the lateral stiffness is increased. Small deformation. Therefore, early wear starting from the concave arc portion 13 is unlikely to occur, and the concave arc portion 13 may be disposed in the outer shoulder region Yso.

  In addition, it is preferable to form each linear inclination part 10 in parallel mutually like this example from a viewpoint of abrasion resistance.

  Further, the adoption of the inclined main groove 9 can greatly improve the dry grip performance and the wear resistance performance, but in this embodiment, in order to further improve the sea area ratio Sc of the tread pattern in the central region Yc The ratio Ss / Sc to the sea area ratio Ss of the tread pattern in the shoulder region Ys is set to 70 to 90%. This is to reduce the sea area ratio Ss in the shoulder region Ys, which has a small contribution to drainage to the front of the tire when wet, to 70 to 90% of the sea area ratio Sc in the central region Yc, which has a large contribution. This is because the dry grip performance including the lateral grip can be further effectively improved. If the ratio Ss / Sc is less than 70%, the wet grip performance is insufficient. Conversely, if it exceeds 90%, the effect of improving the dry grip performance is insufficient.

  At this time, the sea area ratio S in the entire tread contact surface is preferably in the range of 0.15 to 0.4, as in the case of a conventional high-performance tire premised on both public road driving and race driving. If it is less than 0.15, the wet grip performance on a public road will be insufficient, and if it exceeds 0.4, the dry grip performance on a race will be insufficient. As is well known, the sea area ratio means the ratio of the groove area of the tread groove to the entire surface of the tread pattern.

  In high-performance tires premised on both road running and racing, it is necessary to improve the wet grip performance in driving and braking in a well-balanced manner. Therefore, in the present embodiment, as shown in FIG. 5, the sum Sf of the groove areas of the rotation direction inclined portion 9 f that inclines in the rotation direction F from the tire equator C toward the tread contact end E in the inclined main groove 9. And the ratio Sr / Sf to the total groove area Sr of the non-rotating direction inclined portion 9r inclined in the non-rotating direction R is set to 90 to 150%.

  Here, in the vertical V-shaped tread pattern (for example, the pattern of FIG. 7B) configured by the non-rotating direction inclined portion 9r, drainage to the front of the tire during driving is good, but drainage during braking is not. bad. Therefore, by setting the ratio Sr / Sf in the range of 90 to 150%, the drainage performance to the front of the tire during braking is enhanced. If it is less than 90%, the drainage at the time of driving is insufficient, and if it exceeds 150%, the drainage at the time of braking becomes insufficient. As the ratio Sr / Sf approaches 100%, the tread pattern becomes a laterally V-shaped pattern, so the difference in cornering force obtained when turning on a dry road surface during braking and driving decreases. Driving stability can be increased. From such a viewpoint, it is preferable that the lower limit value of the ratio Sr / Sf is 98% or more and the upper limit value is 140% or less.

  Next, FIG. 6 illustrates another embodiment of the present invention. In the figure, the first inclined main groove 9A is provided with a notch 15 in the vicinity of the convex point position Q of the convex arc portion 11, and the portion where the angle θ is 10 ° or less is deleted. Therefore, early wear starting from the convex arc portion 11 can be suppressed, and wear resistance can be further improved.

  Further, in this example, the linear inclined portion 10 in the inclined main groove 9 is illustrated as a preferred case extending in a straight line, but the angle θ of the groove portion passing through the central region Yc of the linear inclined portion 10 and The angle θ of the groove portion passing through the shoulder region Ys can be formed in a polygonal line shape that is different from each other within the angle range. At this time, the groove portions may be connected by curved portions.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in various aspects, such as being able to be formed as a tire for general passenger cars. .

A tire having a tire size of 255 / 40R17 based on the tread pattern shown in FIG. 2 was prototyped with the specifications shown in Table 1, and the dry grip performance, wet grip performance, and wear resistance were compared with those of the comparative example. The specifications are the same except for the tread pattern.
(1) Dry grip performance and wet grip performance;
Using a passenger tire (2000 cc) with a test tire mounted on all wheels under the conditions of a rim (9J × 17) and internal pressure (230 kPa), run the gymkana on a JAF-certified gymkhana course, and run time when dry and wet Was measured. The running time is the best time during two time attacks. The shorter the running time, the better the grip performance.

(2) Abrasion resistance;
The state of wear after the tests for the dry grip performance and the wet grip performance were evaluated by a visual inspection and a five-point method using Comparative Example 1 as three points. The larger the value, the better the wear resistance.

It is sectional drawing of the tire of one Example of this invention. It is an expanded view which shows the tread pattern. It is an expanded view explaining the 1st-3rd inclination main groove. It is an expanded view explaining the 4th-6th inclination main groove. It is an expanded view which shows the rotation direction inclination part and non-rotation direction inclination part of an inclination main groove. It is an expanded view which shows the other Example of the tread pattern of this invention. (A), (B) is a development view which illustrates the conventional tread pattern used for a high-performance tire.

Explanation of symbols

2 Tread portion 9 Inclined main groove 9f Rotating direction inclined portion 9r Non-rotating direction inclined portion 10 Straight inclined portion 11 Convex arc portion Yc Central region Yci Outside central region Ys Shoulder region Yso Outside shoulder region

Claims (2)

A pneumatic tire provided with an inclined main groove including a linearly inclined portion inclined linearly with respect to the circumferential direction without having a longitudinal main groove extending substantially continuously in the circumferential direction on the tread portion,
The tread portion has a ratio Ss / Sc between the sea area ratio Sc of the tread pattern in the central region of 50% of the tread width centered on the tire equator and the sea area ratio Ss of the tread pattern in the shoulder region on both outer sides thereof. 70-90%
The inclined main groove has an angle with respect to the circumferential direction in the central region in the range of 0 to 70 °, and in the linear inclined portion in a range of 35 to 70 °, and in the shoulder region, the angle with respect to the circumferential direction. In the range of 0 to 90 ° and in the linear inclined portion, the range of 50 to 90 °,
The inclined main groove does not include a convex arc portion that is convex toward the vehicle outer side and has an angle of 10 ° or less with respect to the circumferential direction in the outer shoulder region that faces the vehicle outer side when the vehicle is mounted.
In addition, among the inclined main grooves, the total groove area Sf of the rotation direction inclined portions inclined in the tire rotation direction from the tire equator toward the tread end, and the total groove area of the non-rotation direction inclination portions inclined in the non-rotation direction. A pneumatic tire characterized in that the ratio Sr / Sf to Sr is 90 to 150%.   The inclined main groove does not include a convex arc portion that is convex toward the vehicle outer side and has an angle with respect to the circumferential direction of 10 ° or less in an outer central region portion that faces the vehicle outer side in the central region. The pneumatic tire according to claim 1.

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