JP5541228B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  Reducing the rolling resistance of a pneumatic tire is useful for improving the fuel efficiency of an automobile. In order to reduce the rolling resistance of a tire, for example, there is a technique of applying a rubber compounded with silica to a tread.

Akimasa Doi, “Recent Technology Trends in Tires”, Journal of Japan Rubber Association, September 1998, Vol. 71, p. 588-594

  The method of reducing the rolling resistance of a pneumatic tire described in Non-Patent Document 1 is to improve the material, but the rolling resistance is reduced by changing the structure of the pneumatic tire, and the cornering power There is a possibility that it can be secured. An object of the present invention is to provide a structure capable of reducing the rolling resistance of a pneumatic tire and ensuring cornering power.

  The present invention has a cylindrical annular structure, a rubber layer provided on the outer side of the annular structure along the circumferential direction of the annular structure and serving as a tread portion, and a fiber coated with rubber. A carcass portion provided at least on both sides in the width direction of the cylindrical structure including the annular structure and the rubber layer, and centering on an end on the outer side in the width direction of the annular structure. The minimum thickness ta of the rubber layer in the direction perpendicular to the surface on the radial outer side of the annular structure or the extended surface of the surface on the radial outer side in the first region of 10 mm on the outer side and 10 mm on the inner side in the width direction, The ratio ta / tb with respect to the maximum thickness tb of the rubber layer in the direction orthogonal to the surface on the radially outer side of the annular structure in the second region which is the region on the inner side in the width direction from the first region is 0 or less. A pneumatic tire, characterized in that is 0.7 or less.

  In the present invention, in the region from the end of the annular structure on the outer side in the width direction to 15 mm toward the outer side in the width direction, the contour shape in the meridional section of the tread portion when the pneumatic tire is set to a predetermined air pressure is It is preferable to have an arc that is recessed toward the inside of the pneumatic tire.

  In this invention, it is preferable that the shortest distance from the edge part in the width direction outer side of the said cyclic structure to the outline of the said tread part is 0.5 mm or more and 10 mm or less in a meridian cross section.

  In the present invention, it is preferable that the annular structure is embedded in the rubber layer and is not exposed to the surface on the radially outer side of the rubber layer.

  In the present invention, it is preferable that the outer side of the rubber layer and the outer side of the annular structure are parallel to the central axis except for a groove portion of the rubber layer.

  The present invention can provide a structure capable of reducing the rolling resistance of a pneumatic tire and ensuring cornering power.

FIG. 1 is a meridional sectional view of a tire according to this embodiment. FIG. 2-1 is a perspective view of an annular structure included in the tire according to the present embodiment. FIG. 2-2 is a plan view of the annular structure included in the tire according to the present embodiment. FIG. 3 is an enlarged view of a carcass portion included in the tire according to the present embodiment. FIG. 4 is a meridional sectional view of the annular structure and the rubber layer. FIG. 5 is a meridional cross-sectional view showing an outer end portion in the width direction of the tire according to the present embodiment. FIG. 6 is a meridional cross-sectional view showing an outer end portion in the width direction of a tire according to a comparative example. FIG. 7 is a meridional cross-sectional view showing a widthwise outer end portion of a tire according to another example of the present embodiment. FIG. 8 is a meridional cross-sectional view showing a width direction outer side end portion of a tire according to another example of the present embodiment. FIG. 9 is a meridional cross-sectional view showing the outer end in the width direction of the tire according to the present embodiment. FIG. 10 is a meridional cross-sectional view showing the outer end in the width direction of the tire according to the comparative example. FIG. 11A is a meridional cross-sectional view illustrating an example in which the tire according to the present embodiment is applied to an LT tire. FIG. 11B is a meridional sectional view illustrating an example in which the tire according to the present embodiment is applied to an LT tire. FIG. 11C is a meridional cross-sectional view illustrating an example in which the tire according to this embodiment is applied to an LT tire. FIG. 12A is a meridional sectional view illustrating an example in which the tire according to the present embodiment is applied to a TB tire. FIG. 12-2 is a meridional cross-sectional view illustrating an example in which the tire according to this embodiment is applied to a TB tire.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that are equivalent. Furthermore, the constituent elements described below can be appropriately combined. In addition, various omissions, substitutions, or changes of components can be made without departing from the scope of the present embodiment.

  In order to reduce the rolling resistance of a pneumatic tire (hereinafter referred to as a tire if necessary), if the eccentric deformation of the tire is increased to the limit, the contact area between the tire and the road surface is reduced and the contact pressure is increased. As a result, the viscoelastic energy loss due to the deformation of the tread portion increases, and the rolling resistance increases. The present inventors paid attention to this point, and tried to reduce rolling resistance and improve operability by ensuring a contact area between the tire and the road surface and maintaining eccentric deformation. Eccentric deformation is a deformation in a primary mode in which a tire tread ring (crown region) is displaced vertically while maintaining a circular shape. In order to secure a contact area between the tire and the road surface and maintain eccentric deformation, the tire according to the present embodiment is, for example, outside the cylindrical annular structure manufactured by a thin metal plate. A rubber layer is provided in the circumferential direction, and the rubber layer is installed as a tread portion.

  FIG. 1 is a meridional sectional view of a tire according to this embodiment. FIG. 2-1 is a perspective view of an annular structure included in the tire according to the present embodiment. FIG. 2-2 is a plan view of the annular structure included in the tire according to the present embodiment. FIG. 3 is an enlarged view of a carcass portion included in the tire according to the present embodiment. As shown in FIG. 1, the tire 1 is an annular structure. An axis passing through the center of the annular structure is a central axis (Y axis) of the tire 1. The tire 1 is filled with air when in use.

  The tire 1 rotates about a central axis (Y axis) as a rotation axis. The Y axis is a central axis and a rotation axis of the tire 1. An axis that is orthogonal to the Y axis that is the central axis (rotation axis) of the tire 1 and that is parallel to the road surface on which the tire 1 contacts the ground is an X axis, and an axis that is orthogonal to the Y axis and the X axis is a Z axis. The direction parallel to the Y axis is the width direction of the tire 1. A direction passing through the Y axis and perpendicular to the Y axis is the radial direction of the tire 1. Further, the circumferential direction around the Y axis is the circumferential direction of the pneumatic tire 1 (the direction indicated by the arrow CR in FIG. 1).

  As shown in FIG. 1, the tire 1 includes a cylindrical annular structure 10, a rubber layer 11, and a carcass portion 12. The annular structure 10 is a cylindrical member. The rubber layer 11 becomes a tread portion of the tire 1 by being provided on the surface 10so on the radially outer side of the annular structure 10 toward the circumferential direction of the annular structure 10. As shown in FIG. 3, the carcass portion 12 includes fibers 12F covered with rubber 12R. In the present embodiment, as shown in FIG. 1, the carcass portion 12 passes between the bead portions 13 through the radially inner side of the annular structure 10. That is, the carcass part 12 is continuous between both bead parts 13 and 13. The carcass portion 12 may be provided on both sides in the width direction of the annular structure 10 and may not be continuous between both bead portions 13 and 13. Thus, as shown in FIG. 3, the carcass portion 12 has a direction (that is, a width direction) parallel to the central axis (Y axis) of the cylindrical structure 2 including at least the annular structure 10 and the rubber layer 11. As long as it is provided on both sides.

  In the tire 1, in the meridional section of the structure 2, the outer side 11 so (tread surface of the tire 1) of the rubber layer 11 and the surface 10 so on the outer side in the radial direction of the annular structure 10 are grooves S formed on the tread surface. It is more preferable that the shape is the same except for the portion and is parallel (including tolerance and error). In the present embodiment, the shape of the tread surface of the tire 1 is such that the outer side in the width direction (more specifically, between the ground contact surface of the rubber layer 11 and the side portion SP of the tire 1) in the meridional cross section of the tire 1. It is recessed toward the inside. That is, in the tire 1, the thickness of the rubber layer 11 is smaller on the outer side in the width direction than on the inner side in the width direction. By making the shape of the tread surface of the tire 1 and the rubber layer 11 as described above, it is possible to ensure cornering power while reducing rolling resistance.

The annular structure 10 shown in FIGS. 2-1 and 2-2 is a metal structure. That is, the annular structure 10 is made of a metal material. The metal material used for the annular structure 10 preferably has a tensile strength of 450 N / mm ² or more and 2500 N / mm ² or less, more preferably 600 N / mm ² or more and 2400 N / mm ² or less, Furthermore, 800 N / mm ² or more and 2300 N / mm ² or less are preferable. If the tensile strength is in such a range, the annular structure 10 can ensure sufficient strength and rigidity and can secure necessary toughness. The metal material that can be used for the annular structure 10 may be in the range described above for the tensile strength, but is preferably spring steel, high-tensile steel, stainless steel, or titanium (including titanium alloy). Of these, stainless steel is preferable because it has high corrosion resistance and easily obtains the above-described tensile strength range.

  The product of the tensile strength (MPa) and the thickness (mm) of the annular structure 10 is used as a pressure resistance parameter. The pressure resistance parameter is a parameter that is a measure of the resistance to the internal pressure of a gas (for example, air or nitrogen) filled in the tire 1. The withstand voltage parameter is preferably 200 or more and 1700 or less, and 250 or more and 1600 or less. If it is this range, the upper limit of the use pressure of the tire 1 can be ensured, and safety | security can fully be ensured. Moreover, if it is the said range, since the thickness of the cyclic structure 10 is not increased and it is not necessary to use a material with high breaking strength, it is suitable for mass production. Since it is not necessary to increase the thickness of the annular structure 10, the annular structure 10 can ensure the durability of repeated bending. Moreover, since it is not necessary to use a material with high breaking strength, the annular structure 10 and the tire 1 can be manufactured at low cost. As a passenger vehicle tire (PC tire), the pressure resistance parameter is preferably 200 or more and 1000 or less, and more preferably 250 or more and 950 or less. As a light truck tire (LT tire), the pressure resistance parameter is preferably 300 or more and 1200 or less, and more preferably 350 or more and 1100 or less. As a truck / bus tire (TB tire), the pressure resistance parameter is preferably 500 or more and 1700 or less, and more preferably 600 or more and 1600 or less.

  When manufacturing the annular structure 10 with stainless steel, use martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, austenitic / ferritic duplex stainless steel, precipitation hardening stainless steel in the classification of JIS G4303. Is preferred. By using these stainless steels, the annular structure 10 having excellent tensile strength and toughness can be obtained. Moreover, it is more preferable to use precipitation hardening stainless steel (SUS631, SUS632J1) among the stainless steels described above.

  The annular structure 10 may have a plurality of through holes that penetrate the inner peripheral surface and the outer periphery. A rubber layer 11 is attached to at least one of the radially outer side and the radially inner side of the annular structure 10. The rubber layer 11 is attached to the annular structure by chemical bonding with the annular structure 10. The through hole has an effect of strengthening physical coupling between the annular structure 10 and the rubber layer 11. For this reason, since the cyclic structure 10 having the through hole has improved bonding strength with the rubber layer 11 due to chemical and physical action (anchor effect), the annular structure 10 is securely fixed to the rubber layer 11. As a result, the durability of the tire 1 is improved.

The cross-sectional area of the through hole is preferably 0.1 mm ² or more and 100 mm ² or less, more preferably 0.12 mm ² or more and 80 mm ² or less, and further preferably 0.15 mm ² or more and 70 mm ² or less. If it is such a range, the unevenness | corrugation of the carcass part 12 can be suppressed, and the coupling | bonding by adhesion | attachment, ie, a chemical coupling | bonding, can fully be utilized. Furthermore, if it is the range mentioned above, the physical effect mentioned above, ie, an anchor effect, will occur most effectively. By these actions, the bond between the annular structure 10 and the rubber layer 11 can be strengthened.

  When the annular structure 10 has a through hole, the shape is not limited, but a circular shape or an elliptical shape is preferable. The through hole preferably has an equivalent diameter of 4 × A / C (C is the circumferential length of the through hole and A is the opening area of the through hole) of 0.5 mm to 10 mm. The through hole has a circular shape and a diameter of 1.0 mm or more and 8.0 mm or less is more preferable. Within such a range, physical and chemical bonds can be used effectively, so that the annular structure 10 and the rubber layer 11 are more firmly bonded. As will be described later, the equivalent diameters or diameters of the through holes may not all be the same.

  The total area of the through holes is preferably 0.5% or more and 30%, more preferably 1.0% or more and 20% or less, and still more preferably 1.5%, with respect to the surface area on the radially outer side of the annular structure 10. It is 15% or less. If it is such a range, the intensity | strength of the cyclic structure 10 is securable, utilizing a physical and chemical coupling | bonding effectively. As a result, the annular structure 10 and the rubber layer 11 are more firmly bonded, and the rigidity necessary for the annular structure 10 can be ensured. The intervals between the through holes may be unequal intervals or may be equal intervals. By doing in this way, the contact shape of the tire 1 can also be controlled.

  The annular structure 10 can be manufactured by abutting and welding short-side throws of a rectangular plate or a rectangular plate with a plurality of through holes drilled. In this way, the annular structure 10 can be manufactured relatively easily. Moreover, the manufacturing method of the cyclic structure 10 is not limited to this. For example, the annular structure 10 may be manufactured by forming a plurality of holes in the outer periphery of the cylinder and then scraping the inside of the cylinder.

  The surface 10so on the radially outer side of the annular structure 10 and the inner side 11si of the rubber layer 11 are in contact with each other. In the present embodiment, the annular structure 10 and the rubber layer 11 are fixed by, for example, an adhesive. With such a structure, force can be transmitted between the annular structure 10 and the rubber layer 11. The means for fixing the annular structure 10 and the rubber layer 11 is not limited to the adhesive. Moreover, it is preferable that the annular structure 10 is not exposed to the outside in the radial direction of the rubber layer. In this way, the annular structure 10 and the rubber layer 11 can be more reliably fixed. Further, the annular structure 10 may be embedded in the rubber layer 11. Even if it does in this way, the annular structure 10 and the rubber layer 11 can be fixed more reliably.

The rubber layer 11 includes synthetic rubber, natural rubber, or a rubber material in which these are mixed, and carbon, SiO _2, or the like added as a reinforcing material to the rubber material. The rubber layer 11 is an endless belt-like structure. As shown in FIG. 1, in this embodiment, the rubber layer 11 has a plurality of grooves (main grooves) S on the outer side 11so. The rubber layer 11 may have lug grooves in addition to the grooves S.

  The carcass portion 12 is a strength member that serves as a pressure vessel together with the annular structure 10 when the tire 1 is filled with air. The carcass portion 12 and the annular structure 10 support the load acting on the tire 1 by the internal pressure of the air filled therein, and withstand the dynamic load that the tire 1 receives during traveling. In the present embodiment, the carcass portion 12 of the tire 1 has an inner liner 14 on the inner side. The inner liner 14 suppresses leakage of air filled in the tire 1. Both carcass portions 12 each have a bead portion 13 on the radially inner side. The bead portion 13 is fitted to a wheel rim to which the tire 1 is attached. The carcass portion 12 may be mechanically coupled to the wheel rim.

  FIG. 4 is a meridional sectional view of the annular structure and the rubber layer. The elastic modulus of the annular structure 10 is preferably 70 GPa or more and 250 GPa or less, and more preferably 80 GPa or more and 230 GPa or less. Also. The thickness tm of the annular structure 10 is preferably 0.1 mm or more and 0.8 mm or less. Within this range, it is possible to ensure the durability of repeated bending while ensuring the pressure resistance performance. The product of the elastic modulus and the thickness tm (referred to as a stiffness parameter) of the annular structure 10 is preferably 10 or more and 500 or less, and more preferably 15 or more and 400 or less.

  By setting the stiffness parameter in the above range, the annular structure 10 has a greater stiffness in the meridional section. For this reason, when the tire 1 is filled with air and when the tire 1 contacts the road surface, the annular structure 10 suppresses deformation in the meridional section of the rubber layer 11 serving as a tread portion. As a result, the tire 1 is suppressed from loss of viscoelastic energy due to the deformation. Moreover, the rigidity in the radial direction of the annular structure 10 is reduced by setting the rigidity parameter within the above range. For this reason, the tread portion of the tire 1 is flexibly deformed at the contact portion with the road surface, similarly to the conventional pneumatic tire. With such a function, the tire 1 is eccentrically deformed while avoiding local strain and stress concentration in the ground contact portion, so that the strain in the ground contact portion can be dispersed. As a result, in the tire 1, local deformation of the rubber layer 11 in the ground contact portion is suppressed, so that a ground contact area is ensured and rolling resistance is reduced.

  Furthermore, since the tire 1 has a large in-plane rigidity of the annular structure 10 and can secure the contact area of the rubber layer 11, the contact length in the circumferential direction can be ensured. For this reason, the lateral force generated when the steering angle is input to the tire 1 increases. As a result, the tire 1 can obtain a large cornering power. Further, when the annular structure 10 is made of metal, the air filled in the tire 1 hardly penetrates the annular structure 10. As a result, there is an advantage that the air pressure of the tire 1 can be easily managed. For this reason, it is possible to suppress a decrease in the air pressure of the tire 1 even for a usage mode in which the tire 1 is not filled with air over a long period of time.

  The distance tr (the thickness of the rubber layer 11) between the surface 10so on the radially outer side of the annular structure 10 and the outer side 11so of the rubber layer 11 is preferably 3 mm or more and 20 mm or less. By setting the distance tr in such a range, it is possible to suppress excessive deformation of the rubber layer 11 during cornering while ensuring the ride comfort. The dimension (annular structure width) Wm of the annular structure 10 in the direction parallel to the central axis (Y axis) of the annular structure 10, that is, the width direction, is in the direction parallel to the central axis (Y axis) shown in FIG. 50% (W × 0.5) or more and 95% (W × 0.95) or less of the total width of the tire 1 (in a state where it is assembled on a wheel having a JATMA prescribed rim width and filled with 300 kPa of air) is preferable. . When Wm is smaller than W × 0.5, the rigidity in the meridional section of the annular structure 10 is insufficient, and as a result, the region for maintaining the eccentric deformation with respect to the tire width decreases. As a result, the effect of reducing the rolling resistance and the cornering power may be reduced. Further, if Wm exceeds W × 0.95, the tread portion may buckle and deform the annular structure 10 in the central axis (Y-axis) direction at the time of ground contact, which may cause deformation of the annular structure 10. By setting W × 0.5 ≦ Wm ≦ W × 0.95, it is possible to maintain cornering power while reducing rolling resistance, and to suppress deformation of the annular structure 10.

  In the meridional section shown in FIG. 1, the tire 1 has an outer surface 11 so of the rubber layer 11, that is, a profile of the tread surface, which has the same shape as the surface 10 so on the radially outer side of the annular structure 10 except for the groove S portion. It is preferable. With such a structure, when the tire 1 is grounded or rolled, the rubber layer 11 serving as the tread portion and the annular structure 10 are deformed in substantially the same manner. As a result, the tire 1 is less deformed by the rubber layer 11, so that the loss of viscoelastic energy is smaller and the rolling resistance is also smaller.

  If the outer side 11so of the rubber layer 11 and the surface 10so on the outer side in the radial direction of the annular structure 10 protrude toward the outer side in the radial direction of the tire 1 or protrude toward the inner side in the radial direction, The pressure distribution is non-uniform. As a result, local strain and stress concentration occur in the grounding portion, and the rubber layer 11 may be locally deformed in the grounding portion. In the present embodiment, as shown in FIG. 3, in the tire 1, the outer side 11 so (tread surface of the tire 1) of the rubber layer 11 and the surface 10 so on the radially outer side of the annular structure 10 have the same shape (preferably It is preferable that the rubber layer 11 and the annular structure 10 (that is, the structure 2) are parallel to the central axis (Y axis) (including tolerance and error). With such a structure, the ground contact portion of the tire 1 can be made substantially flat. Since the tire 1 has a uniform pressure distribution in the contact portion, local distortion and stress concentration in the contact portion are suppressed, and local deformation of the rubber layer 11 in the contact portion is suppressed. As a result, since the loss of viscoelastic energy is reduced, the rolling resistance of the tire 1 is also reduced. Moreover, since local deformation | transformation of the rubber layer 11 in a contact part is suppressed, a tire can ensure a ground contact area and can ensure the contact length of the circumferential direction simultaneously. For this reason, the tire 1 can also ensure cornering power.

  In the present embodiment, the shape of the rubber layer 11 in the meridional section is such that the outer side 11so of the rubber layer 11 and the surface 10so on the radially outer side of the annular structure 10 are parallel to these central axes (Y-axis). The shape is not particularly limited. For example, the shape of the rubber layer 11 in the meridional section may be a trapezoid or a parallelogram. When the shape of the rubber layer 11 in the meridional section is a trapezoid, either the upper base or the lower base of the trapezoid may be the outer side 11so of the rubber layer 11. In any case, only the portion of the annular structure 10 may be parallel to the tread surface profile (excluding the groove portion) of the tire 1. Next, the shape of the tread surface of the tire 1 will be described in more detail.

FIG. 5 is a meridional cross-sectional view showing an outer end portion in the width direction of the tire according to the present embodiment. FIG. 6 is a meridional cross-sectional view showing the outer end in the width direction of the tire according to the comparative example. 7 and 8 are meridional cross-sectional views showing the outer ends in the width direction of tires according to other examples of the present embodiment. The tire 1 has a predetermined distance W b (5 mm in this embodiment) on the outer side in the width direction and a predetermined distance W a (in this embodiment) on the inner side in the width direction, with the end portion 10t on the outer side in the width direction of the annular structure 10 as the center. 5 mm) in the first region A, the minimum thickness ta of the rubber layer 11 in the direction orthogonal to the surface 10so on the radially outer side of the annular structure 10 or the extended surface Pso of the surface 10so on the radially outer side, from the first region A The ratio ta / tb with respect to the maximum thickness tb of the rubber layer in the direction orthogonal to the surface 10so on the radially outer side of the annular structure 10 in the second region B, which is also the inner region in the width direction, is 0 or more and 0.7 or less. It is. ta / tb is more preferably 0.1 or more and 0.5 or less. When the tire 1 is a PC tire or an LT tire, both Wa and Wb are preferably 5 mm. In the case of a heavy load tire such as a TB tire, both Wa and Wb may be 10 mm.

  The rolling resistance of the tire 101 (the tire according to the comparative example) using the annular structure 10 is greatly reduced. However, since the strain of the rubber layer 11 (tread rubber) is concentrated near the end of the annular structure 10 in the width direction, the ground contact length tends to be longer at the ground contact end, which improves the cornering power. There is room. In the present embodiment, the thickness of the rubber layer 11 in the vicinity of the end in the width direction of the annular structure 10 is set by setting ta / tb to be 0 or more and 0.7 or less, more preferably 0.1 or more and 0.5 or less. By reducing the thickness (thinning the gauge), it is possible to ensure cornering power while reducing rolling resistance.

  If ta / tb is within the above range, the thickness of the rubber layer 11 may be abruptly reduced at the contact end as in the tire 1a shown in FIG. If ta / tb is within the above range, the rubber layer 11 may have a groove 15b at the ground contact end as in the tire 1b shown in FIG. In this case, the minimum thickness ta of the rubber layer 11 is such that the groove bottom of the groove 15b and the annular structure 10 in the direction orthogonal to the surface 10so on the radially outer side of the annular structure 10 or the extended surface Pso of the surface 10so on the radially outer side. It is the distance to the surface 10so on the radially outer side or the extended surface Pso of the surface 10so on the radially outer side.

  In the tire 1, the contour shape in the meridional section of the tread portion when the tire 1 is set to a predetermined air pressure in the region from the end 10 t of the annular structure 10 on the outer side in the width direction to 15 mm toward the outer side in the width direction 1 has an arc 15 that is recessed toward the inside. The arc 15 has a center c on the outer side in the radial direction and the outer side in the width direction of the tire 1. The radius of curvature of the arc is preferably 3 mm or more and 150 mm or less, more preferably 5 mm or more and 100 mm or less, and most preferably 8 mm or more and 70 mm or less. By doing in this way, since the quantity of the rubber | gum of the edge part in the width direction outer side of the cyclic structure 10 becomes appropriate, cornering power can be ensured more. The predetermined air pressure is an air pressure when the tires 1, 1a and 1c are assembled on a wheel having a JATMA prescribed rim width, and is 300 kPa.

  FIG. 9 is a meridional cross-sectional view showing the outer end in the width direction of the tire according to the present embodiment. FIG. 10 is a meridional cross-sectional view showing the outer end in the width direction of the tire according to the comparative example. In the present embodiment, when the tire 1a is a PC tire, the shortest distance R from the end 10t on the outer side in the width direction of the annular structure 10 to the tread contour (excluding the lug groove) is 0 in the meridional section. It is preferable that it is 5 mm or more and 5 mm or less. Moreover, when the tire 1a is a heavy load tire, the shortest distance R from the end 10t on the outer side in the width direction of the annular structure 10 to the contour of the tread (excluding the lug groove) is 0.5 mm or more in the meridional section. It is preferable that it is 10 mm or less. By doing in this way, since the quantity of the rubber | gum of the edge part in the width direction outer side of the cyclic structure 10 becomes appropriate, cornering power can be ensured more. The same applies to the tire 1 shown in FIG. 5 and the tire 1b shown in FIG. In the tire 101 of the comparative example shown in FIG. 10, in the meridional section, the shortest distance Rc from the end portion 10 t on the outer side in the width direction of the annular structure 10 to the contour of the tread portion (excluding the lug groove) exceeds the above range. ing. For this reason, the tire 101 of the comparative example can achieve a reduction in rolling resistance, but the cornering power is smaller than that of the tires 1, 1a, 1b of the present embodiment.

  FIGS. 11A to 11C are meridional sectional views showing an example in which the tire according to the present embodiment is applied to an LT tire. A tire 1c shown in FIG. 11A has a groove 15c in the rubber layer 11 in the vicinity of both end portions 10t on the outer side in the width direction of the annular structure 10. A tire 1d shown in FIG. 11-2 has an arc 15d in the rubber layer 11 in the vicinity of both end portions 10t on the outer side in the width direction of the annular structure 10. A tire 1e shown in FIG. 11C has a groove 15e in the rubber layer 11 in the vicinity of both end portions 10t on the outer side in the width direction of the annular structure 10. The groove 15e of the tire 1d has a smaller dimension in the radial direction on the outer side in the width direction than the groove 15c of the tire 1c shown in FIG. The tires 1c, 1e, and 1d have grooves 15c and 15e and an arc 15d, and ta / tb is in the above-described range. For this reason, tire 1c, 1e, 1d can aim at coexistence with reduction of rolling resistance, and ensuring of cornering power.

  FIGS. 12A and 12B are meridional cross-sectional views showing an example in which the tire according to this embodiment is applied to a TB tire. A tire 1 f shown in FIG. 12A has a groove 15 f in the rubber layer 11 in the vicinity of both end portions 10 t on the outer side in the width direction of the annular structure 10. The groove 15f is inclined with respect to the equator plane of the tire 1f, and the opening is directed outward in the width direction. A tire 1c shown in FIG. 12-2 has a groove 15g in the rubber layer 11 in the vicinity of both end portions 10t on the outer side in the width direction of the annular structure 10. The groove 15g is larger at the groove bottom than at the opening. The tires 1f and 1g have grooves 15f and 15g, and ta / tb is in the above-described range. For this reason, the tires 1f and 1g can achieve both reduction in rolling resistance and securing of cornering power.

1, 1a, 1b, 1c, 1d, 1e, 1f, 101 Pneumatic tire (tire)
2 structure 10 annular structure 10t end 10so surface 11 rubber layer 12 carcass part 13 bead part 14 inner liner 15, 15d arcs 15b, 15c, 15e, 15f, 15g groove

Claims (4)

A cylindrical annular structure made of a metal plate ,
A rubber layer provided on the outside of the annular structure along the circumferential direction of the annular structure and serving as a tread portion;
A carcass portion having fibers coated with rubber and provided at least on both sides in the width direction of the cylindrical structure including the annular structure and the rubber layer;
The surface on the radially outer side of the annular structure or the surface on the radially outer side in a first region having a width of 10 mm on the outer side in the width direction and 10 mm on the inner side in the width direction with the end on the outer side in the width direction of the annular structure as the center. In the direction perpendicular to the surface on the radially outer side of the annular structure in the second region, which is the inner region in the width direction than the first region, in the direction perpendicular to the extended surface of the rubber layer The ratio ta / tb to the maximum thickness tb of the rubber layer is 0 or more and 0.7 or less,
The pneumatic tire according to claim 1, wherein an outer side of the rubber layer and an outer side of the annular structure are parallel to a central axis of the annular structure except for a groove portion of the rubber layer.   The contour shape in the meridional section of the tread portion when the pneumatic tire is set to a predetermined air pressure in the region from the end of the annular structure on the outer side in the width direction to 15 mm toward the outer side in the width direction is the pneumatic shape. The pneumatic tire according to claim 1, wherein the pneumatic tire has an arc that is recessed toward the inside of the tire.   3. The pneumatic tire according to claim 1, wherein in a meridian cross section, a shortest distance from an end portion on the outer side in the width direction of the annular structure to an outline of the tread portion is 0.5 mm or more and 10 mm or less.   The pneumatic tire according to any one of claims 1 to 3, wherein the annular structure is embedded in the rubber layer and is not exposed on a surface of the rubber layer on a radially outer side.

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