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US-12617237-B2 - Motorcycle tire

US12617237B2US 12617237 B2US12617237 B2US 12617237B2US-12617237-B2

Abstract

A motorcycle tire can include a tread portion, sidewall portions, bead portions, and a carcass. The tread portion can include a tread reinforcing layer and a tread rubber. The tread reinforcing layer can include a belt layer and a band layer. A development width of the band layer can be smaller than that of the belt layer. The tread rubber can include a crown rubber and shoulder rubbers. A hardness at 100° C. of each shoulder rubber can be higher than a hardness at 100° C. of the crown rubber, a complex elastic modulus at 100° C. of each shoulder rubber can be higher than a complex elastic modulus at 100° C. of the crown rubber, and a 300% modulus at 100° C. of each shoulder rubber can be higher than a 300% modulus at 100° C. of the crown rubber.

Inventors

  • Yoshihisa Noguchi

Assignees

  • SUMITOMO RUBBER INDUSTRIES, LTD.

Dates

Publication Date
20260505
Application Date
20241023
Priority Date
20231101

Claims (18)

  1. 1 . A motorcycle tire comprising: a tread portion; a pair of sidewall portions; a pair of bead portions; and a carcass extending on and between the pair of bead portions, wherein the tread portion includes a tread reinforcing layer placed outward of the carcass in a tire radial direction, and a tread rubber placed outward of the tread reinforcing layer in the tire radial direction, the tread reinforcing layer includes a belt layer including a plurality of belt cords inclined with respect to a tire circumferential direction, and a band layer placed outward of the belt layer in the tire radial direction and including at least one band cord helically wound in the tire circumferential direction, a development width of the band layer is smaller than a development width of the belt layer, the tread rubber includes a crown rubber placed in a region including a tire equator, and shoulder rubbers each placed outward of the crown rubber in a tire axial direction in a region including a tread edge, a hardness at 100° C. of each shoulder rubber is higher than a hardness at 100° C. of the crown rubber, a complex elastic modulus at 100° C. of each shoulder rubber is higher than a complex elastic modulus at 100° C. of the crown rubber, a 300% modulus at 100° C. of each shoulder rubber is higher than a 300% modulus at 100° C. of the crown rubber, a breaking strength of the at least one band cord is higher than a breaking strength of each of the plurality of belt cords, the belt layer is comprised of a first ply and a second ply, the band layer straddles the tire equator and has a width extending in the tire axial direction in a plan view of the tread portion to provide increased stiffness in the tire circumferential direction, and the belt layer extends in the circumferential direction in the plan view of the tread portion to provide increased stiffness in the tire axial direction.
  2. 2 . The motorcycle tire according to claim 1 , wherein a loss tangent at 100° C. of each shoulder rubber is higher than a loss tangent at 100° C. of the crown rubber.
  3. 3 . The motorcycle tire according to claim 1 , wherein a hardness at 50° C. of each shoulder rubber is higher than a hardness at 50° C. of the crown rubber, a complex elastic modulus at 50° C. of each shoulder rubber is higher than a complex elastic modulus at 50° C. of the crown rubber, and a 300% modulus at 50° C. of each shoulder rubber is higher than a 300% modulus at 50° C. of the crown rubber.
  4. 4 . The motorcycle tire according to claim 3 , wherein a loss tangent at 50° C. of each shoulder rubber is higher than a loss tangent at 50° C. of the crown rubber.
  5. 5 . The motorcycle tire according to claim 3 , wherein the hardness at 50° C. of the crown rubber is 44 to 48 degrees, and the complex elastic modulus at 50° C. of the crown rubber is 3.2 to 3.8 MPa.
  6. 6 . The motorcycle tire according to claim 5 , wherein the hardness at 50° C. of each shoulder rubber is 47 to 51 degrees, and the complex elastic modulus at 50° C. of each shoulder rubber is 4.0 to 4.6 MPa.
  7. 7 . The motorcycle tire according to claim 3 , wherein the hardness at 50° C. of each shoulder rubber is not less than 105% and not greater than 125% the hardness at 50° C. of the crown rubber, the complex elastic modulus at 50° C. of each shoulder rubber is not less than 105% and not greater than 150% the complex elastic modulus at 50° C. of the crown rubber, and the 300% modulus at 50° C. of each shoulder rubber is not less than 105% and not greater than 150% the 300% modulus at 50° C. of the crown rubber.
  8. 8 . The motorcycle tire according to claim 1 , wherein the hardness at 100° C. of the crown rubber is 38 to 42 degrees, the complex elastic modulus at 100° C. of the crown rubber is 2.1 to 2.7 MPa, and the 300% modulus at 100° C. of the crown rubber is 4.0 to 4.8 MPa.
  9. 9 . The motorcycle tire according to claim 8 , wherein the hardness at 100° C. of each shoulder rubber is 40 to 44 degrees, the complex elastic modulus at 100° C. of each shoulder rubber is 2.4 to 3.0 MPa, and the 300% modulus at 100° C. of each shoulder rubber is 4.7 to 5.5 MPa.
  10. 10 . The motorcycle tire according to claim 1 , wherein, in a tire meridian cross-section in a 10 kPa state where the motorcycle tire is fitted on a standardized rim and inflated to an internal pressure of 10 kPa, a radius of curvature Rc of a ground-contact surface of the crown rubber is less than 95% of a tire cross-sectional width, and a radius of curvature Rb of a ground-contact surface of each shoulder rubber is larger than the radius of curvature Rc.
  11. 11 . The motorcycle tire according to claim 1 , wherein a development width of a ground-contact surface of the crown rubber is 80% to 120% of the development width of the band layer.
  12. 12 . The motorcycle tire according to claim 1 , wherein a development width of a ground-contact surface of the crown rubber is larger than the development width of the band layer.
  13. 13 . The motorcycle tire according to claim 1 , wherein the hardness at 100° C. of each shoulder rubber is not less than 105% and not greater than 125% the hardness at 100° C. of the crown rubber, the complex elastic modulus at 100° C. of each shoulder rubber is not less than 105% and not greater than 150% of the complex elastic modulus of the crown rubber, and the 300% modulus at 100° C. of each shoulder rubber is not less than 105% and not greater than 150% the 300% modulus at 100° C. of the crown rubber.
  14. 14 . The motorcycle tire according to claim 1 , wherein the band layer is composed of a jointless band, and the belt layer consists of the first ply and the second ply.
  15. 15 . The motorcycle tire according to claim 1 , wherein a development width a ground-contact surface of each shoulder rubber is 60% to 90% of a development width of the crown rubber, and the development width of the band layer is 20% to 80% of a development width the tread portion.
  16. 16 . A motorcycle tire comprising: a tread portion; a pair of sidewall portions; a pair of bead portions; and a carcass extending on and between the pair of bead portions, wherein the tread portion includes a tread reinforcing layer placed outward of the carcass in a tire radial direction, and a tread rubber placed outward of the tread reinforcing layer in the tire radial direction, the tread reinforcing layer includes a belt layer including a plurality of belt cords inclined with respect to a tire circumferential direction, and a band layer placed outward of the belt layer in the tire radial direction and including at least one band cord helically wound in the tire circumferential direction, a development width of the band layer is smaller than a development width of the belt layer, the tread rubber includes a crown rubber placed in a region including a tire equator, and shoulder rubbers each placed outward of the crown rubber in a tire axial direction in a region including a tread edge, a hardness at 100° C. of each shoulder rubber is higher than a hardness at 100° C. of the crown rubber, a complex elastic modulus at 100° C. of each shoulder rubber is higher than a complex elastic modulus at 100° C. of the crown rubber, a 300% modulus at 100° C. of each shoulder rubber is higher than a 300% modulus at 100° C. of the crown rubber, and the development width the band layer is 20% to 60% of the development width of the belt layer.
  17. 17 . A motorcycle tire comprising: a tread portion; a pair of sidewall portions; a pair of bead portions; and a carcass extending on and between the pair of bead portions, wherein the tread portion includes a tread reinforcing layer placed outward of the carcass in a tire radial direction, and a tread rubber placed outward of the tread reinforcing layer in the tire radial direction, the tread reinforcing layer includes a belt layer including a plurality of belt cords inclined with respect to a tire circumferential direction, and a band layer placed outward of the belt layer in the tire radial direction and including at least one band cord helically wound in the tire circumferential direction, a development width of the band layer is smaller than a development width of the belt layer, the tread rubber includes a crown rubber placed in a region including a tire equator, and shoulder rubbers each placed outward of the crown rubber in a tire axial direction in a region including a tread edge, a hardness at 100° C. of each shoulder rubber is higher than a hardness at 100° C. of the crown rubber, a complex elastic modulus at 100° C. of each shoulder rubber is higher than a complex elastic modulus at 100° C. of the crown rubber, a 300% modulus at 100° C. of each shoulder rubber is higher than a 300% modulus at 100° C. of the crown rubber, the belt layer includes a first ply and a second ply, a development width of the first belt ply and a development width of the second belt ply is 80% to 100% a development width of the tread portion, the first ply includes a first plurality of belt cords inclined in a first direction with respect to the tire circumferential direction, and the second ply includes a second plurality of belt cords inclined in a second direction opposite to the first direction with respect to the tire circumferential direction.
  18. 18 . The motorcycle tire according to claim 17 , wherein each of the belt cords of the first plurality and/or each of the belt cords of the second plurality are formed of a non-twisted single cord.

Description

CROSS REFERENCE TO RELATED APPLICATION The present application claims priority to Japanese patent application JP 2023-187956, filed on Nov. 1, 2023, the entire contents of which are incorporated herein by reference in its entirety. BACKGROUND Field The present disclosure relates to a motorcycle tire. Background Art Japanese Patent No. 6946646 proposes a motorcycle tire including a tread reinforcing layer in a tread portion thereof. This tire is expected to improve cornering performance by specifying an angle of each belt cord included in the tread reinforcing layer with respect to the tire circumferential direction. In recent years, as the performance of motorcycles and the like has been improved, there has been a growing demand for motorcycle tires to have further improved cornering performance and stability during braking. SUMMARY According to an aspect of the present disclosure, a motorcycle tire can include: a tread portion; a pair of sidewall portions; a pair of bead portions; and a carcass extending on and between the pair of bead portions, wherein the tread portion can include a tread reinforcing layer placed outward of the carcass in a tire radial direction, and a tread rubber placed outward of the tread reinforcing layer in the tire radial direction, the tread reinforcing layer can include a belt layer including a plurality of belt cords inclined with respect to a tire circumferential direction, and a band layer placed outward of the belt layer in the tire radial direction and including at least one band cord helically wound in the tire circumferential direction, a development width of the band layer can be smaller than a development width of the belt layer, the tread rubber can include a crown rubber placed in a region including a tire equator, and shoulder rubbers each placed outward of the crown rubber in a tire axial direction in a region including a tread edge, a hardness at 100° C. of each shoulder rubber can be higher than a hardness at 100° C. of the crown rubber, a complex elastic modulus at 100° C. of each shoulder rubber can be higher than a complex elastic modulus at 100° C. of the crown rubber, and a 300% modulus at 100° C. of each shoulder rubber can be higher than a 300% modulus at 100° C. of the crown rubber. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a motorcycle tire of one or more embodiments of the present disclosure; FIG. 2 is an enlarged perspective view showing inner members of the tire in FIG. 1; FIG. 3 is a development view of a tread rubber and a tread reinforcing layer in FIG. 1; and FIG. 4 shows a profile of a tread portion in a 10 kPa state according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION Hereinafter, one or more embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a tire meridian cross-sectional view, of a motorcycle tire 1 (hereinafter simply referred to as “tire”) according to one or more embodiments of the present disclosure, including a tire rotation axis in a standardized state. The tire 1 can be a tire for the front wheel of a motorcycle, which can be suitable for on-road sports driving. However, the tire 1 according to one or more embodiments of the present disclosure is not limited to such a mode. One or more embodiments of the present disclosure have been made in view of the aforementioned circumstances, and an object of one or more embodiments of the present disclosure, among one or more objects, can be to provide a motorcycle tire that can improve stability during braking and cornering performance. As a result of adopting configurations according to one or more embodiments of the present disclosure, the motorcycle tire can improve stability during braking and cornering performance. In the case of a pneumatic tire for which various standards are defined, the term “standardized state” can be regarded as a state where the tire is fitted on a standardized rim and inflated to a standardized internal pressure and no load is applied to the tire. In the case of a tire for which various standards are not defined, the standardized state can mean a standard use state, corresponding to the purpose of use of the tire, where the tire is not mounted on a vehicle and no load is applied to the tire. In the present specification, unless otherwise specified, dimensions and the like of components of the tire are values measured in the standardized state. In addition, dimensions of components (e.g., inner members of the tire 1) that cannot be measured in the standardized state can be values measured in a state where the tire 1 is made to approximate the standardized state as much as possible. The term “standardized rim” can be regarded as a rim that is defined, in a standard system including a standard on which the tire is based, by the standard for each tire, and can be, for example, the “standard rim” in the JATMA standard, the “Design Rim” in the TRA standard, or t