Motorcycle tire

Abstract

To provide a motorcycle tire which further improves on-road performance and off-road performance.SOLUTION: Provided is a motorcycle tire 1 having a bias structure. Two carcass plies respectively include a plurality of carcass cords inclining at an angle of 20 degrees or more but less than 70 degrees relative to the tire circumferential direction. A tread part 2 comprises: a plurality of lateral grooves 11 extending between tread ends Te of both sides; and a crown block 15 formed between the lateral grooves 11 adjacent in the tire circumferential direction. A length Wc in the tire axial direction of the crown block 15 is 30% or more of a tread development width TW.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire for a motorcycle.

Background Art

[0002] Patent Document 1 below describes a pneumatic tire for a motorcycle in which a crown block row is provided in a tread portion. The crown block row is formed such that the circumferential separation distance between adjacent crown blocks in the tire circumferential direction includes a first distance and a second distance different from the first distance. Further, the centroid of the tread surface of each of the plurality of crown blocks is located at a position spaced apart from the tire equator in the tire axial direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Such a pneumatic tire for a motorcycle is considered suitable for traveling on a course where on-road and off-road are mixed. In recent years, it has been desired to further improve the turning stability performance on the on-road (hereinafter referred to as "on-road performance") and the turning stability performance on the off-road (hereinafter referred to as "off-road performance").

[0005] The present invention has been devised in view of the above problems, and an object thereof is to provide a tire for a motorcycle that can further improve on-road performance and off-road performance.

Means for Solving the Problems

[0006] The present invention relates to a motorcycle tire including a tread portion and a carcass having a bias structure, wherein the carcass includes at least two carcass plies, each of the two carcass plies includes a plurality of carcass cords inclined at an angle of 20 degrees or more and less than 70 degrees with respect to the tire circumferential direction, the inclination of the carcass cords of the two carcass plies is opposite to each other, the tread portion includes a plurality of lateral grooves extending between tread ends on both sides and crown blocks formed between the lateral grooves adjacent to each other in the tire circumferential direction, and the axial length of the crown blocks in the tire axial direction is 30% or more of the tread development width.

Advantages of the Invention

[0007] By adopting the above configuration, the motorcycle tire of the present invention can further improve on-road performance and off-road performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings include exaggerated expressions and expressions different from the actual structural dimensional ratios in order to assist in understanding the present invention. Also, when there are a plurality of embodiments, the same or common elements are denoted by the same reference numerals throughout the specification, and duplicate descriptions are omitted.

[0010] Figure 1 is a developed view of a tread portion 2 of a motorcycle tire (hereinafter sometimes referred to as "tire") 1 showing an embodiment of the present invention. Figure 2(A) is a sectional view taken along line A-A of Figure 1. In Figures 1 and 2(A), a pneumatic tire capable of traveling on-road and off-road is shown as a preferred embodiment. Further, the tire 1 shown in Figures 1 and 2(A) is suitable for a front tire of a motorcycle.

[0011] In this specification, unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in a normal state. The "normal state" is, in the case of a pneumatic tire, a no-load state in which the tire 1 is rim-mounted on a normal rim (not shown) and filled with a normal internal pressure.

[0012] The "normal rim" is a rim defined for each tire in a standard system including the standard on which the tire 1 is based. For example, in the case of JATMA, it is the "standard rim", in the case of TRA, it is the "Design Rim", and in the case of ETRTO, it is the "Measuring Rim".

[0013] The "normal internal pressure" is an air pressure defined for each tire in a standard system including the standard on which the tire 1 is based. In the case of JATMA, it is the "maximum air pressure", in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is the "INFLATION PRESSURE".

[0014] As shown in Figures 1 and 2(A), the tire 1 includes a tread portion 2 and a carcass 6. The carcass 6 includes at least two carcass plies 6A and 6B.

[0015] FIG. 2(B) is a developed view of carcass plies 6A and 6B. As shown in FIG. 2, each of the two carcass plies 6A and 6B includes a plurality of carcass cords 6c inclined at an angle θ1 of 20 degrees or more and less than 70 degrees with respect to the tire circumferential direction. The two carcass plies 6A and 6B have the carcass cords 6c inclined in opposite directions to each other. Thus, the tire 1 of the present invention has a bias structure. Thereby, since the tire 1 can flex as a whole, when cornering, the outer diameter difference becomes large inside and outside in the tire axial direction within the contact surface, and a large lateral force (centripetal force) can be obtained. Further, in a bias structure that flexes as a whole of the tire, in the tread portion 2, for example, the difference in rigidity between the portion where the groove is provided and the portion where the groove is not provided becomes small, so that even when the camber angle of the tire 1 is changed, a sudden change in grip is suppressed. For this reason, the on-road performance and the off-road performance are improved. Note that the angle θ1 of the carcass cords 6c of each of the carcass plies 6A and 6B is desirably 50 degrees or less, and more desirably 40 degrees or less.

[0016] As shown in FIG. 1, the tread portion 2 includes a plurality of lateral grooves 11 extending between the tread ends Te and Te on both sides, and crown blocks 15 formed between the lateral grooves 11 adjacent in the tire circumferential direction. Such lateral grooves 11 extending between the tread ends Te and Te can easily discharge the mud fitted into the lateral grooves 11 during off-road driving, and can highly exhibit the edge effect of the lateral grooves 11. Thereby, the off-road performance is improved. The tread end Te corresponds to the end of the contact surface of the tread portion 2 during cornering at the maximum camber angle in this specification. The tread end Te is, for example, set to the position forming the tire maximum width position M (shown in FIG. 2(A)). The tire maximum width position M is the position that protrudes most outward in the tire axial direction on a virtual outer surface specified excluding protrusions such as characters and rim protectors provided on the outer surface 1a of the tire 1 in this specification.

[0017] The axial length Wc of the crown block 15 is 30% or more of the tread development width TW. Such a crown block 15 can suppress a sharp decrease in rigidity at the initial stage of turning with a relatively small camber angle and maintain good transient characteristics. Therefore, the motorcycle tire of the present invention can further improve on-road performance and off-road performance. If the length Wc of the crown block 15 is excessively large, the rigidity of the tread portion 2 may become excessively large, and there is a risk that the entire tire cannot flex. For this reason, the length Wc of the crown block 15 is preferably 35% or more, more preferably 70% or less, and even more preferably 65% or less of the tread development width TW. The tread development width TW is, in this specification, the axial distance between the tread ends Te, Te when the tread portion 2 is developed on a plane.

[0018] As shown in FIG. 2(A), for the tire 1, the ratio (f / C) of the length f in the radial direction of the tire between the tire cross-sectional width C and the maximum width position M of the tire and the outer end 1e in the radial direction of the tire 1 is preferably 0.25 or more, preferably 0.6 or less, and more preferably 0.5 or less. Since the ratio (f / C) is 0.25 or more, the entire tire becomes more flexible and it becomes easier to obtain lateral force during turning. Also, since the ratio (f / C) is 0.6 or less, the running at the initial stage of turning is stable. The tire cross-sectional width C is, in this specification, the axial distance at the maximum width position M of the tire. Further, the outer end 1e of the tire 1 is specified by the tread surface 2a of the tread portion 2 on the tire equator Co. When a groove or the like is provided in the tire equator Co, the outer end 1e is specified by a virtual tread surface (not shown) obtained by filling the groove or the like.

[0019] The tire 1 includes a pair of sidewall portions 3 connected to both sides in the axial direction of the tread portion 2, and a pair of bead portions 4 connected to the inner side in the radial direction of each sidewall portion 3. Each carcass ply 6A, 6B extends in a toroidal shape, for example, between the bead portions 4 on both sides.

[0020] As shown in FIG. 1, the tread portion 2 includes land portions 10 which are separated by transverse grooves 11 adjacent in the tire circumferential direction. The land portions 10 are formed between the tread ends Te, Te on both sides. Further, the land portion 10 includes a first land portion 10A and a second land portion 10B. In the first land portion 10A of the present embodiment, the length L1 in the tire circumferential direction increases from the tire equator Co toward the tread ends Te on both sides. The first land portion 10A, for example, has a continuously increasing length L1 from the tire equator Co toward the tread ends Te on both sides. In the second land portion 10B of the present embodiment, the length L2 in the tire circumferential direction decreases from the tire equator Co toward the tread ends Te on both sides. The second land portion 10B, for example, has a continuously decreasing length L2 from the tire equator Co toward the tread ends Te on both sides. The first land portion 10A and the second land portion 10B are, for example, provided alternately in the tire circumferential direction.

[0021] In the present embodiment, the minimum value Lf of the length L1 of the first land portion 10A is larger than the minimum value Lh of the length L2 of the second land portion 10B. In other words, the length Lf in the tire circumferential direction of the first land portion 10A on the tire equator Co is larger than the length Lh in the tire circumferential direction of the second land portion 10B on the tread end Te. Thereby, since the rigidity near the tire equator Co of the first land portion 10A that contacts the ground at the initial stage of turning where the running opportunity is large is maintained high, the on-road performance and the off-road performance are improved.

[0022] In each first land portion 10A, the ratio (L1n / L1x) of the minimum value L1n of the length in the tire circumferential direction to the maximum value L1x of the length in the tire circumferential direction is desirably 0.60 or more, more desirably 0.65 or more, desirably 0.80 or less, and more desirably 0.75 or less. Further, in the second land portion 10B, the ratio (L2n / L2x) of the minimum value L2n of the length in the tire circumferential direction to the maximum value L2x of the length in the tire circumferential direction is desirably 0.50 or more, more desirably 0.55 or more, desirably 0.70 or less, and more desirably 0.65 or less.

[0023] When the first land portion 10A and the second land portion 10B adjacent to each other in the tire circumferential direction are combined to form a land portion group 10S, the land portion groups 10Sa and 10Sb adjacent to each other in the tire circumferential direction form pitch variations with different lengths in the tire circumferential direction. The ratio (Ls / Lt) of the length Ls in the tire circumferential direction of the land portion group 10Sa to the length Lt in the tire circumferential direction of the land portion group 10Sb is desirably 60% or more, more desirably 65% or more, desirably 96% or less, and more desirably 92% or less. In the ratio (Ls / Lt), the larger numerical value is used as the denominator in the length Ls in the tire circumferential direction of the land portion group 10Sa and the length Lt in the tire circumferential direction of the land portion group 10Sb.

[0024] In the present embodiment, the crown block 15 includes a first crown block 16 and a second crown block 17 that is adjacent to the first crown block 16 in the tire circumferential direction and has a larger length in the tire axial direction than the first crown block 16. In the present embodiment, the first crown block 16 is disposed on the first land portion 10A. The second crown block 17 is disposed on the second land portion 10B, for example.

[0025] Further, the tread portion 2 of the present embodiment includes a first crown vertical groove 12 that defines the first crown block 16 and a second crown vertical groove 13 that defines the second crown block 17. The first crown vertical groove 12 and the second crown vertical groove 13 connect the lateral grooves 11 adjacent to each other in the tire circumferential direction, for example. In the present embodiment, the first crown vertical groove 12 and the second crown vertical groove 13 are alternately provided in the tire circumferential direction. The first crown vertical groove 12 and the second crown vertical groove 13 of the present embodiment are provided on both sides in the tire axial direction with the tire equator Co interposed therebetween. Note that the tread portion 2 of the present embodiment has a line-symmetric shape with the tire equator Co as the axis of symmetry.

[0026] Furthermore, the tread portion 2 includes a shoulder vertical groove 14 located outside the first crown vertical groove 12 in the tire axial direction. In the present embodiment, the shoulder vertical groove 14 is provided in the first land portion 10A and connects the lateral grooves 11, 11 adjacent to each other in the tire circumferential direction.

[0027] As a result, the first land portion 10A further includes a pair of middle blocks 18 defined by the first crown longitudinal groove 12 and the shoulder longitudinal groove 14, and a pair of first shoulder blocks 19 defined by the shoulder longitudinal groove 14 and the tread edge Te. Further, the second land portion 10B further includes a pair of second shoulder blocks 20 defined by the second crown longitudinal groove 13 and the tread edge Te.

[0028] The lateral groove 11 extends, for example, in an arc shape convex in one of the tire circumferential directions. In the present embodiment, the groove width center line 11s of the lateral groove 11 extends in an arc shape convex in one of the tire circumferential directions. The groove width W1 of the lateral groove 11 is desirably 20% or more, more desirably 30% or more, desirably 50% or less, and more desirably 40% or less of the length (minimum value L1n) in the tire circumferential direction of the land portion 10 (the first land portion 10A) adjacent to the lateral groove 11. Since the groove width W1 of the lateral groove 11 is 20% or more of the length of the land portion 10 in the tire circumferential direction, the mud that has become stuck in the lateral groove 11 can be smoothly discharged. Since the groove width W1 of the lateral groove 11 is 50% or less of the length of the land portion 10 in the tire circumferential direction, a significant decrease in the rigidity of the tread portion 2 can be suppressed. In this specification, the groove width of the groove including the lateral groove 11 is the length orthogonal to the groove width center line.

[0029] FIG. 3 is a developed view of the tread portion 2. As shown in FIG. 3, the lateral groove 11 includes, for example, a first lateral groove 11A extending in an arc shape convex in the first tire circumferential direction, and a second lateral groove 11B extending in an arc shape convex in the direction opposite to the first lateral groove 11A. In the present embodiment, the first lateral groove 11A and the second lateral groove 11B are arranged alternately in the tire circumferential direction.

[0030] FIG. 4 is a cross-sectional view taken along line B-B of FIG. 3. As shown in FIGS. 3 and 4, the lateral groove 11 includes a tie bar 21 with a raised groove bottom 11d. The tie bar 21 suppresses the deformation of the lateral groove 11 during cornering and helps to maintain good transient characteristics.

[0031] The tie bar 21 is connected to, for example, the second crown longitudinal groove 13. Such a tie bar 21 increases the rigidity of the portion of the tread part 2 that is easily deformed by the groove, suppressing deterioration of transient characteristics during turning. In the present embodiment, the tie bar 21 is connected to both longitudinal sides in the longitudinal direction of the second crown longitudinal groove 13.

[0032] In the present embodiment, the tie bar 21 is located outside the first crown longitudinal groove 12 in the tire axial direction. The tie bar 21 is disposed, for example, between the first crown longitudinal groove 12 and the shoulder longitudinal groove 14. The tie bar 21 of the present embodiment is disposed without overlapping with either the groove width center line 12s of the first crown longitudinal groove 12 or the groove width center line 14s of the shoulder longitudinal groove 14 in the tire axial direction. Such a tie bar 21 does not prevent the smooth flow of mud from the first crown longitudinal groove 12 and the shoulder longitudinal groove 14 to the lateral groove 11.

[0033] From the viewpoint of smoothly discharging the mud stuck in the lateral groove 11 while suppressing a decrease in the rigidity of the tread part 2, the length Lu in the tire axial direction of the tie bar 21 is desirably 5% or more of the tread development width TW, more desirably 7% or more, desirably 15% or less, and more desirably 13% or less. Similarly, the raised height Ha of the tie bar 21 is desirably 10% or more of the groove depth d1 of the lateral groove 11, more desirably 15% or more, desirably 30% or less, and more desirably 25% or less.

[0034] As shown in FIG. 3, the first crown longitudinal groove 12 extends, for example, in an arcuate shape convex toward the inner side in the tire axial direction. Thereby, it is possible to ensure high lateral rigidity in the vicinity of both circumferential sides in the tire circumferential direction where the lateral rigidity (lateral rigidity) of the first crown block 16 in the tire axial direction tends to be small, so that the running performance at the initial stage of turning can be improved. In the present embodiment, the groove edges 12d, 12d on both sides of the first crown longitudinal groove 12 extend in an arcuate shape convex toward the inner side in the tire axial direction.

[0035] In the present embodiment, the first crown longitudinal groove 12 is displaced in the tire axial direction from the second crown longitudinal groove 13. As a result, since the portion where the rigidity is reduced due to the groove is displaced in the tire axial direction, deterioration of the transient characteristics during turning is suppressed, and stable turning running becomes possible. If the first crown longitudinal groove 12 is excessively displaced in the tire axial direction from the second crown longitudinal groove 13, the rigidity difference in the tire axial direction between the first crown block 16 and the second crown block 17 increases, and conversely, the transient characteristics during turning running may deteriorate. For this reason, the displacement length WA in the tire axial direction between the first crown longitudinal groove 12 and the second crown longitudinal groove 13 is desirably 10% or more of the groove width W2 of the first crown longitudinal groove 12, more desirably 15% or more, desirably 220% or less, and more desirably 200% or less. The displacement length WA is specified by one end 12e in the tire circumferential direction of the groove width center line 12s of the first crown longitudinal groove 12 and the other end 13i in the tire circumferential direction of the groove width center line 13s of the second crown longitudinal groove 13.

[0036] The groove width W2 of the first crown longitudinal groove 12 and the groove width W3 of the second crown longitudinal groove 13 are desirably 4% or more and 15% or less of the tread development width TW, and more desirably 10% or less. Since each groove width W2, W3 is 4% or more of the tread development width TW, the mud caught in the lateral groove 11 can be smoothly discharged through the respective crown longitudinal grooves 12, 13. Since each groove width W2, W3 is 15% or less of the tread development width TW, the rigidity in the vicinity of each crown longitudinal groove 12, 13 is maintained, so that deterioration of the transient characteristics can be suppressed. In the present embodiment, the groove width W2 of the first crown longitudinal groove 12 is the same as the groove width W3 of the second crown longitudinal groove 13. The term "the same" includes not only the case where the difference in groove width (W2 - W3) is 0 mm, but also the aspect where the absolute value of the difference in groove width |W2 - W3| is 2 mm or less.

[0037] The second crown longitudinal groove 13 extends in an arc shape convex toward the tread end Te side, for example. In other words, the second crown longitudinal groove 13 extends in an arc shape convex in the opposite direction to the first crown longitudinal groove 12. Such first crown longitudinal groove 12 and second crown longitudinal groove 13 exhibit an edge effect in multiple directions, thus providing stable turning performance. In the present embodiment, for the second crown longitudinal groove 13, the groove edges 13d, 13d on both sides thereof extend in an arc shape convex toward the tread end Te side.

[0038] In the present embodiment, the shoulder longitudinal groove 14 extends in the tire circumferential direction. The shoulder longitudinal groove 14 extends parallel to the tire circumferential direction, for example. Since the shoulder longitudinal groove 14 is located outside the first crown longitudinal groove 12 in the tire axial direction, when cornering, the groove edge 14d extending in the longitudinal direction exhibits a large edge effect. In the present embodiment, the shoulder longitudinal groove 14 has a groove width W4 smaller than the groove width W2 of the first crown longitudinal groove 12.

[0039] In the present embodiment, the shoulder longitudinal groove 14 is axially misaligned with the second crown longitudinal groove 13. As a result, the portion where the rigidity is reduced due to the groove is axially misaligned, so that the deterioration of the transient characteristics during cornering is suppressed, and stable cornering is possible. The shoulder longitudinal groove 14 is located outside the second crown longitudinal groove 13 in the tire axial direction, for example. The axial misalignment length WB between the shoulder longitudinal groove 14 and the second crown longitudinal groove 13 is desirably 1.5 times or more, more desirably 1.7 times or more, desirably 4.0 times or less, and more desirably 3.5 times or less of the groove width W3 of the second crown longitudinal groove 13. The misalignment length WB is specified by one end 13e in the tire circumferential direction of the groove width center line 13s of the second crown longitudinal groove 13 and the other end 14i in the tire circumferential direction of the groove width center line 14s of the shoulder longitudinal groove 14.

[0040] FIG. 5 is a developed view of the tread portion 2. As shown in FIG. 5, the first crown block 16 is formed as a plane block in which grooves or sipes are not formed on its tread surface 16a. Such a first crown block 16 is useful for stable turning performance during on-road driving. In this specification, the sipe is a notch-shaped recess having a width of less than 1.5 mm, and is clearly distinguished from a groove having a width of 1.5 mm or more. The grooves include the lateral grooves 11, the longitudinal grooves 12 to 14, and the fine grooves 23 to 26 described later.

[0041] In this embodiment, the second crown block 17 includes a longitudinal fine groove 23 extending in the tire circumferential direction and a lateral fine groove 24 extending in the tire axial direction. The longitudinal fine groove 23 and the lateral fine groove 24 are arranged to intersect each other. Such a longitudinal fine groove 23 and a lateral fine groove 24 appropriately reduce the rigidity of the second crown block 17 having a relatively large length in the tire axial direction, and help to increase the outer diameter difference inside and outside in the tire axial direction within the contact surface during turning. Each of the longitudinal fine groove 23 and the lateral fine groove 24 terminates at both ends within the second crown block 17. The groove width W5 of the longitudinal fine groove 23 and the groove width W6 of the lateral fine groove 24 are formed to be smaller than the groove width W4 of the shoulder longitudinal groove 14, for example.

[0042] The longitudinal fine groove 23 is located, for example, at the middle 17c in the tire axial direction of the second crown block 17. In this embodiment, the longitudinal fine groove 23 is located on the tire equator Co. The longitudinal fine groove 23 is located, for example, at the longitudinal center 24c of the lateral fine groove 24. In this embodiment, the lateral fine groove 24 is located at the longitudinal center 23c of the longitudinal fine groove 23.

[0043] The middle block 18 is provided with a middle lateral fine groove 25 that extends from the shoulder longitudinal groove 14 toward the tire equator Co side and terminates within the middle block 18. Such a middle lateral fine groove 25 increases the shearing force during off-road driving. The middle lateral fine groove 25 is located, for example, at the longitudinal center 14c of the shoulder longitudinal groove 14.

[0044] The first shoulder block 19 is provided with a shoulder transverse groove 26 that extends from the shoulder longitudinal groove 14 toward the tread end Te side and terminates within the first shoulder block 19. The shoulder transverse groove 26 is located, for example, at the longitudinal center 14c of the shoulder longitudinal groove 14.

[0045] The shoulder transverse groove 26 extends so as to form a single virtual transverse groove with the middle transverse groove 25 via the shoulder longitudinal groove 14. In this specification, the phrase "forming a single virtual transverse groove" means a mode in which a virtual line 26v obtained by extending the groove width center line 26s of the shoulder transverse groove 26 coincides with the groove width center line 25s of the middle transverse groove 25. Further, the phrase "forming a single virtual transverse groove" also includes a mode in which the virtual line 26v coincides with the middle transverse groove 25 at 50% or more of the tire axial length Ld of the middle transverse groove 25.

[0046] The second shoulder block 20 is formed as a plane block in the same manner as the first crown block 16.

[0047] A chamfered portion 29 with the block edges (not shown) cut off is provided around each of the blocks 16 to 20. The chamfered portion 29 is provided adjacent to, for example, the transverse groove 11 and each of the longitudinal grooves 12 to 14. Such a chamfered portion 29 helps to suppress the occurrence of chipping and cracking in each of the blocks 16 to 20 and maintain high maneuverability.

[0048] The sealant ratio S / L of the tread portion 2 is desirably 15% or more, more desirably 20% or more, desirably 50% or less, and more desirably 40% or less. Since the sealant ratio S / L is 15% or more, the shear force against mud can be increased. Since the sealant ratio S / L is 50% or less, the rigidity of the tread portion 2 can be maintained high. In this specification, the sealant ratio S / L is the ratio of the total surface area S of the grooves and the sipes to the total surface area L of the tread surface 2a (shown in FIG. 1) of the tread portion 2. The total surface area S is the difference (T - L) between the total surface area T of a virtual tread surface (not shown) obtained by filling all the grooves and the sipes and the total surface area L of the tread surface 2a.

[0049] FIG. 6 is a developed view of the tread portion 2 of another embodiment. The tire 1 shown in FIG. 6 is suitable for, for example, a rear tire of a motorcycle. In the tread portion 2 of this embodiment, no tie bars are provided in the lateral grooves 11. Such a tread portion 2 exerts a large shearing force on mud, thereby enhancing traction in off-road driving. In the tread portion 2 of this embodiment, no tie bars are provided in the first lateral groove 11A and the second lateral groove 11B.

[0050] Further, in the tread portion 2 of this embodiment, the axial displacement length WA in the tire axial direction between the first crown longitudinal groove 12 and the second crown longitudinal groove 13 is preferably 10% or more of the groove width W2 of the first crown longitudinal groove 12, more preferably 20% or more, preferably 60% or less, and more preferably 50% or less.

[0051] As described above, the particularly preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the illustrated embodiments and can be implemented in various forms.

Example

[0052] A motorcycle tire having the basic patterns of FIGS. 1 and 6 was prototyped based on the specifications in Table 1. Then, the on-road performance and off-road performance of the test tire were tested. The test method and the common specifications of each test tire are as follows. Tire size (FIG. 1): 120 / 70-16 (front) Tire size (FIG. 6): 150 / 70-14 (rear) Inner pressure: 200 kPa (front), 225 kPa (rear)

[0053] <Off-road performance · Off-road performance> Each test tire was mounted on the front and rear wheels of the following motorcycle. The test rider drove this motorcycle on a test course of a dry asphalt road surface and a muddy road surface. Both performances were evaluated based on the sensory evaluation of the test rider. The results are shown in scores with Comparative Example 1 as 100, and the larger the numerical value, the better. Motorcycle: Displacement 500 cc The test results are shown in Table 1. In Table 1, "1.0 TW" means an aspect where the lateral grooves extend between the tread ends. Also, "0.7 TW" means an aspect where the lateral grooves have a length in the tire axial direction of 70% of the tread width measured from the tire equator. Further, "A" means the same aspect as in FIG. 1 for the front tire and the same aspect as in FIG. 6 for the rear tire.

[0054] [Table 1]

[0055] As a result of the test, it was confirmed that the tires of the examples have improved on-road performance and off-road performance compared to the tires of the comparative examples.

[0056] [Appendix] The present invention includes the following aspects.

[0057] [Invention 1] A motorcycle tire including a tread portion and a carcass having a bias structure, wherein the carcass includes at least two carcass plies, each of the two carcass plies includes a plurality of carcass cords inclined at an angle of 20 degrees or more and less than 70 degrees with respect to the tire circumferential direction, the two carcass plies have the carcass cords inclined in opposite directions to each other, the tread portion includes a plurality of lateral grooves extending between the tread ends on both sides and crown blocks formed between the adjacent lateral grooves in the tire circumferential direction, the axial length of the crown block in the tire axial direction is 30% or more of the tread width, A motorcycle tire. [Invention 2] For the motorcycle tire according to the first aspect of the present invention, the ratio (f / C) of the tire cross-sectional width C to the length f in the tire radial direction between the maximum width position of the tire and the outer end in the tire radial direction of the tire is 0.25 or more. [The third aspect of the present invention] For the motorcycle tire according to the first or second aspect of the present invention, the sealant ratio of the tread portion is 15% to 50%. [The fourth aspect of the present invention] For the motorcycle tire according to any one of the first to third aspects of the present invention, the plurality of lateral grooves include a tiber with a raised groove bottom. [The fifth aspect of the present invention] For the motorcycle tire according to the fourth aspect of the present invention, the raised height of the tiber is 10% or more of the groove depth of the lateral groove. [The sixth aspect of the present invention] The crown block includes a first crown block and a second crown block that is adjacent to the first crown block in the tire circumferential direction and has a greater length in the tire axial direction than the first crown block. The tread portion includes a first crown longitudinal groove that defines the first crown block and a second crown longitudinal groove that defines the second crown block. For the motorcycle tire according to the fourth or fifth aspect of the present invention, the tiber is located outside the first crown longitudinal groove in the tire axial direction. [The seventh aspect of the present invention] For the motorcycle tire according to the sixth aspect of the present invention, the tiber is connected to the second crown longitudinal groove. [The eighth aspect of the present invention] For the motorcycle tire according to the sixth or seventh aspect of the present invention, the first crown longitudinal groove extends in an arc shape convex toward the inside in the tire axial direction. [The ninth aspect of the present invention] For the motorcycle tire according to any one of the sixth to eighth aspects of the present invention, the first crown longitudinal groove is axially misaligned with the second crown longitudinal groove. [The tenth aspect of the present invention] For the motorcycle tire according to any one of the sixth to ninth aspects of the present invention, the axial misalignment length between the first crown longitudinal groove and the second crown longitudinal groove is 10% or more of the groove width of the first crown longitudinal groove. [Invention 11] The groove width of the first crown longitudinal groove and the groove width of the second crown longitudinal groove are 15% or less of the tread development width. The motorcycle tire according to any one of Inventions 6 to 10 of the present invention. [Invention 12] The tread portion includes land portions divided by the transverse grooves adjacent in the tire circumferential direction. The groove width of the transverse groove is 50% or less of the length of the land portion in the tire circumferential direction. The motorcycle tire according to any one of Inventions 1 to 11 of the present invention. [Invention 13] The land portion includes a first land portion whose length in the tire circumferential direction increases from the tire equator toward the tread ends on both sides, and a second land portion whose length in the tire circumferential direction decreases from the tire equator toward the tread ends on both sides. On the tire equator, the minimum value of the length of the first land portion in the tire circumferential direction is smaller than the minimum value of the length of the second land portion in the tire circumferential direction. The motorcycle tire according to Invention 12 of the present invention.

Explanation of Reference Numerals

[0058] 1 Motorcycle tire 2 Tread portion 11 Transverse groove 15 Crown block Te Tread end Wc Axial length of the crown block in the tire axial direction TW Tread development width

Claims

1. A motorcycle tire including a tread portion and a carcass having a bias structure, wherein the carcass includes at least two carcass plies, each of the two carcass plies includes a plurality of carcass cords inclined at an angle of 20 degrees or more and less than 70 degrees with respect to the tire circumferential direction, the two carcass plies have the carcass cords inclined in opposite directions to each other, the tread portion includes a plurality of lateral grooves extending between tread ends on both sides and crown blocks formed between the adjacent lateral grooves in the tire circumferential direction, the axial length of the crown block in the tire axial direction is 30% or more of the tread development width, A motorcycle tire.

2. The ratio (f / C) of the tire cross-sectional width C to the tire radial length f between the tire maximum width position and the outer end of the tire in the tire radial direction is 0.25 or more. The motorcycle tire according to claim 1.

3. The sealant ratio of the tread portion is 15% to 50%. The motorcycle tire according to claim 1.

4. The plurality of lateral grooves include tie bars with raised groove bottoms. The motorcycle tire according to any one of claims 1 to 3.

5. The raised height of the tie bar is 10% or more of the groove depth of the lateral groove. The motorcycle tire according to claim 4.

6. The crown block includes a first crown block and a second crown block that is adjacent to the first crown block in the tire circumferential direction and has a greater axial length in the tire axial direction than the first crown block, the tread portion includes a first crown longitudinal groove defining the first crown block and a second crown longitudinal groove defining the second crown block, The tire according to claim 4, wherein the tie bar is located outside the first crown longitudinal groove in the tire axial direction.

7. The tire according to claim 6, wherein the tire is connected to the second crown longitudinal groove.

8. The tire according to claim 6, wherein the first crown longitudinal groove extends in an arc shape convex toward the inner side in the tire axial direction.

9. The tire according to claim 6, wherein the first crown longitudinal groove is displaced in the tire axial direction from the second crown longitudinal groove.

10. The tire according to claim 6, wherein the displacement length in the tire axial direction between the first crown longitudinal groove and the second crown longitudinal groove is 10% or more of the groove width of the first crown longitudinal groove.

11. The tire according to claim 6, wherein the groove width of the first crown longitudinal groove and the groove width of the second crown longitudinal groove are 15% or less of the tread development width.

12. The tread portion includes land portions divided by the transverse grooves adjacent in the tire circumferential direction. The tire according to any one of claims 1 to 3, wherein the groove width of the transverse groove is 50% or less of the length in the tire circumferential direction of the land portion.

13. The land portion includes a first land portion whose length in the tire circumferential direction increases from the tire equator toward the tread ends on both sides, and a second land portion whose length in the tire circumferential direction decreases from the tire equator toward the tread ends on both sides. The tire according to claim 12, wherein, on the tire equator, the minimum value of the length in the tire circumferential direction of the first land portion is smaller than the minimum value of the length in the tire circumferential direction of the second land portion.

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