JP7828170B2 - Non-pneumatic tires - Google Patents

Description

The present invention relates to a non-pneumatic tire.

A non-pneumatic tire has been known that supports the load from a vehicle and includes a resin-containing support structure and a tread that is located radially outward of the support structure and extends circumferentially. The support structure includes an inner annular portion, an outer annular portion that is positioned coaxially with the inner annular portion and radially outward of the inner annular portion, and a plurality of spokes that connect the inner and outer annular portions and are arranged circumferentially. The outer annular portion is also located radially inward of the tire and includes a reinforcing layer that extends circumferentially.

On the other hand, it is known to retread used pneumatic tires, that is, to remove the tread from the pneumatic tire by buffing and then reattach the tread.

However, when retreading used pneumatic tires, the belt layer may become exposed and the tread of the retreaded tire may have reduced peel resistance.

Patent Document 1 describes placing an identification layer made of rubber of a different color than the rubber that makes up the tread at a predetermined position in the tire width direction between the belt layer and tread of a pneumatic tire. Furthermore, Patent Document 2 describes changing the position where the tread is attached in the tire radial direction as the number of times a pneumatic tire is retreaded increases.

JP 2011-020508 A Patent No. 6000516

However, as used non-pneumatic tires are retreaded more and more frequently, the outer annular portion is worn beyond its abrasion limit. As a result, the reinforcing layer of the retreaded non-pneumatic tire becomes exposed and its rigidity decreases, leading to tread separation and outer annular breakage.

The present invention aims to provide a non-pneumatic tire that can suppress exposure of the reinforcing layer and maintain rigidity even after retreading.

One aspect of the present invention is a non-pneumatic tire comprising a support structure and a tread located radially outward of the support structure and extending circumferentially. The support structure comprises an inner annular portion, an outer annular portion positioned coaxially with and radially outward of the inner annular portion and including a resin, and a plurality of spokes connecting the inner and outer annular portions and arranged circumferentially. The outer annular portion comprises a first colored layer extending circumferentially and indicating the grinding limit, and a reinforcing layer located radially inward of the first colored layer and extending circumferentially.

The outer annular portion may further include at least one colored layer located radially outward of the first colored layer and extending circumferentially along the tire, the colored layer being different from the color of the first colored layer.

The first colored layer and the at least one colored layer may be exposed in the tire width direction.

The present invention provides a non-pneumatic tire that can suppress exposure of the reinforcing layer and maintain rigidity even after retreading.

1 is a side view showing a non-pneumatic tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1 showing the structure of the outer annular portion and the tread. FIG. 3 is a cross-sectional view showing a modification of the outer annular portion of FIG. 2 . 2 is a cross-sectional view taken along line II-II of FIG. 1. 5 is a partial perspective view of a non-pneumatic tire, as seen obliquely from the portion shown in FIG. 4. FIG.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows a non-pneumatic tire of this embodiment. The non-pneumatic tire 1 includes a support structure 10 and a tread 50. The support structure 10 contains resin and supports a load from a vehicle. The tread 50 is located outward of the support structure 10 in the tire radial direction X and extends along the tire circumferential direction C. The support structure 10 also includes an inner annular portion 20, an outer annular portion 30 arranged coaxially with the inner annular portion 20 and outward of the inner annular portion 20 in the tire radial direction X, and a plurality of spokes 40 connecting the inner annular portion 20 and the outer annular portion 30 and arranged along the tire circumferential direction C. Details of the structure of the non-pneumatic tire 1 will be described later.

Figure 2 shows the structure of the outer annular portion 30. The outer annular portion 30 includes a first colored layer 31 extending along the tire circumferential direction C and indicating the grinding limit, and a reinforcing layer 32 located inward in the tire radial direction X from the first colored layer 31 and extending along the tire circumferential direction C. This prevents the outer annular portion 30 from being ground beyond the grinding limit, even if the number of times a used non-pneumatic tire 1 is retreaded increases. As a result, exposure of the reinforcing layer 32 of the retreaded non-pneumatic tire 1 is suppressed and rigidity is maintained, thereby suppressing peeling of the tread 50 and breakage of the outer annular portion 30.

The polishing limit here refers to the limit at which polishing is possible without exposing the reinforcing layer 32. The reinforcing layer 32 extends circumferentially, contains fiber-reinforced plastic, and is positioned radially inward of the first colored layer 31. The presence of the reinforcing layer 32 suppresses buckling, in which the outer annular portion 30 bends radially in the tire X at the center of the tire width direction Y. As a result, the rigidity of the non-pneumatic tire 1 is maintained and the tread 50's contact with the road surface is improved.

The position of the first colored layer 31 is not particularly limited, as long as it is located further outward in the tire radial direction X than the reinforcing layer 32. In FIG. 2 , the first colored layer 31 is provided over the entire area of the outer annular portion 30 in the tire width direction Y, i.e., exposed in the tire width direction Y. However, it does not have to be provided over the entire area of the outer annular portion 30 in the tire width direction Y. When the first colored layer 31 is exposed in the tire width direction Y, the grinding limit can be visually confirmed from both sides of the non-pneumatic tire 1 in the tire width direction Y without grinding the outer annular portion 30. In this case, the ratio of the width of the first colored layer 31 to the width of the outer annular portion 30 is preferably 50% or more, and more preferably 70% or more, taking into consideration visibility and deformation of the outer annular portion 30 during driving. When the ratio of the width of the first colored layer 31 to the width of the outer annular portion 30 is 50% or more, grinding the outer annular portion 30 beyond the grinding limit is more likely to be prevented, even if the number of times a used non-pneumatic tire 1 is retreaded increases.

The first colored layer 31 is not particularly limited and may contain, for example, a resin and a pigment. Examples of resins include, but are not particularly limited to, silicone resin, urethane resin, and epoxy resin. The resin contained in the first colored layer 31 may be the same as or different from the resin contained in the outer annular portion 30. Furthermore, the pigment contained in the first colored layer 31 is not particularly limited as long as it can be colored a color (e.g., red) that allows the polishing limit to be visually recognized.

The thickness of the first colored layer 31, i.e., its length in the tire radial direction X, is preferably 0.5 mm or more and 5 mm or less, and more preferably 1 mm or more and 3 mm or less. If the thickness of the first colored layer 31 is 0.5 mm or more, the outer annular portion 30 is less likely to be polished beyond the polishing limit, even if the number of times a used non-pneumatic tire 1 is retreaded increases. On the other hand, if the thickness of the first colored layer 31 is 5 mm or less, the number of times a used non-pneumatic tire 1 is retreaded increases.

The fiber-reinforced plastic contained in the reinforcing layer 32 is not particularly limited, but examples include carbon fiber-reinforced plastic, glass fiber-reinforced plastic, etc. Among these, CFRP is preferred.

The thickness of the reinforcing layer 32 is not particularly limited, but is, for example, 1 mm or more and 4 mm or less. Furthermore, the distance between the first colored layer 31 and the reinforcing layer 32, i.e., the distance in the tire radial direction X, is not particularly limited, but is, for example, 1 mm or more and 3 mm or less.

The position where the reinforcing layer 32 is arranged is not particularly limited, as long as it is located inside the first colored layer 31 in the tire radial direction X. Also, although the reinforcing layer 32 is shown in Figure 2 to be provided over the entire area in the tire width direction Y, it does not have to be provided over the entire area in the tire width direction Y.

The resin contained in the outer annular portion 30 is not particularly limited, but examples include thermoplastic elastomers, cross-linked rubber, and other resins. Among these, urethane resin is preferred. Any known urethane resin used in the support structure 10 can be used as the urethane resin. The resin contained in the inner annular portion 20 and the spokes 40 may be the same as or different from the resin contained in the outer annular portion 30.

The thickness of the outer annular portion 30 is not particularly limited, but is, for example, between 4 mm and 15 mm.

The outer annular portion 30 is obtained, for example, by molding each layer sequentially into a cylindrical shape using a mold.

Figure 3 shows a modified structure of the outer annular portion 30. The outer annular portion 30A is similar to the outer annular portion 30 except that it is colored a different color from the first colored layer 31 and is located further outward in the tire radial direction X than the first colored layer 31, and includes a second colored layer 33 and a third colored layer 34 extending along the tire circumferential direction C and continuing from the first colored layer 31. This allows the amount of grinding of the outer annular portion 30A before it reaches its grinding limit to be visually confirmed, thereby enabling the number of times a used non-pneumatic tire 1 has been retreaded to be determined.

The second colored layer 33 is similar to the first colored layer 31, except that it is colored a different color (e.g., blue) from the first colored layer 31. The third colored layer 34 is similar to the first colored layer 31, except that it is colored a different color (e.g., green) from the first colored layer 31. The resins contained in the first colored layer 31, second colored layer 33, and third colored layer 34 may be the same or different. The number of colored layers colored a different color from the first colored layer 31 is not particularly limited.

The non-pneumatic tire 1 is obtained by vulcanizing and bonding the support structure 10 and the tread rubber composition together using, for example, a vulcanization adhesive.

The rubber composition for the tread is not particularly limited, but may contain, for example, natural rubber and carbon black, and may further contain sulfur, silica, etc. Here, the rubber composition for the tread may contain synthetic rubber such as polyisoprene rubber or styrene-butadiene rubber in addition to or instead of natural rubber.

When retreading a used non-pneumatic tire 1, the tread 50 is removed from the non-pneumatic tire 1, for example, by buffing, and then the support structure 10 and the tread rubber composition are vulcanized and bonded together using a vulcanization adhesive.

The structure of the non-pneumatic tire 1 (see Figure 1) will now be described in detail. Figure 1 is a side view of the non-pneumatic tire 1 of this embodiment, viewed from the side in a direction parallel to the tire rotation axis (tire meridian), i.e., along the direction from the front to the back of the page in Figure 1. The non-pneumatic tire 1 shown in Figure 1 is in an unloaded state. Figure 4 is a cross-sectional view taken along line II-II in Figure 1. Figure 5 is a partial perspective view of the non-pneumatic tire 1, viewed obliquely from the portion shown in Figure 4.

In Figures 1 and 5, arrow C indicates the tire circumferential direction. In Figures 1, 4, and 5, arrow X indicates the tire radial direction. In Figures 4 and 5, arrow Y indicates the tire width direction. In Figure 1, the tire width direction Y is the front-to-back direction of the page. In Figure 4, the symbol E is the tire equatorial plane. In Figure 4, the tire circumferential direction C is the front-to-back direction of the page.

The tire circumferential direction C is the direction around the tire rotation axis and is the same direction as the rotation of the non-pneumatic tire 1. The tire radial direction X is the direction perpendicular to the tire rotation axis. The tire width direction Y is the direction parallel to the tire rotation axis. In Figures 4 and 5, one side of the tire width direction Y is indicated as Y1, and the other side of the tire width direction Y is indicated as Y2. The tire equatorial plane E shown in Figure 4 is a plane perpendicular to the tire rotation axis and located at the center of the tire width direction Y.

In the following, the thickness of the inner annular portion 20 and the outer annular portion 30 refers to the dimension in the tire radial direction X. The width of the inner annular portion 20 and the outer annular portion 30 refers to the dimension in the tire width direction Y shown in Figure 4.

The inner annular portion 20 is an annular portion along the tire circumferential direction C that constitutes the inner periphery of the non-pneumatic tire 1. The thickness and width of the inner annular portion 20 are set to a constant value to improve uniformity. A tire wheel (not shown) is placed in the space on the inner periphery of the inner annular portion 20. The inner periphery of the inner annular portion 20 is fitted onto the outer periphery of the tire wheel rim. With the inner annular portion 20 attached to the rim, the non-pneumatic tire 1 is mounted on the tire wheel. The inner periphery of the inner annular portion 20 may be provided with a fitting portion consisting of a protrusion, groove, etc. for fitting with the rim.

The inner annular portion 20 can be formed, for example, from an elastic resin material, but the material is not limited to resin.

The inner annular portion 20 transmits the rotation of the tire wheel to the spokes 40 and the outer annular portion 30. The thickness of the inner annular portion 20 is determined from the viewpoint of achieving lightweight and durability while fully transmitting rotational force to the spokes 40. There are no particular limitations on the thickness of the inner annular portion 20, but it is preferably 2% to 7% of the tire cross-sectional height H shown in Figure 4, and more preferably 3% to 6%.

The inner diameter of the inner annular portion 20 is determined depending on the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the intended use of the vehicle, etc. For example, when considering a replacement for a general pneumatic tire, the inner diameter of the inner annular portion 20 may be, but is not limited to, a dimension of 250 mm or more and 500 mm or less.

The width of the inner annular portion 20 is determined appropriately depending on the use of the vehicle on which the non-pneumatic tire 1 is mounted, the length of the axle, etc. For example, when considering a replacement for a general pneumatic tire, the width of the inner annular portion 20 may be, but is not limited to, a dimension of 100 mm or more and 300 mm or less.

The outer annular portion 30 is an annular portion along the tire circumferential direction C that constitutes the outer periphery of the non-pneumatic tire 1. The outer annular portion 30 is arranged concentrically with the inner annular portion 20 on the outer periphery of the inner annular portion 20. The thickness and width of the outer annular portion 30 are set to a constant value to improve uniformity.

The outer annular portion 30 transmits the rotation of the inner annular portion 20 and spokes 40 to the road surface via the tread 50. The thickness of the outer annular portion 30 is determined from the perspective of achieving lightweight and durability while fully transmitting rotational force from the spokes 40 to the road surface. There are no particular limitations on the thickness of the outer annular portion 30, but it is preferably 2% to 7% of the tire cross-sectional height H shown in Figure 4, and more preferably 2% to 5%.

The inner diameter of the outer annular portion 30 is determined appropriately depending on the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the intended use of the vehicle, etc. For example, when considering a replacement for a general pneumatic tire, the inner diameter of the outer annular portion 30 may be, but is not limited to, a dimension of 420 mm or more and 750 mm or less.

The width of the outer annular portion 30 is determined appropriately depending on the intended use of the vehicle on which the non-pneumatic tire 1 is mounted. For example, when considering a replacement for a general pneumatic tire, the width of the outer annular portion 30 may be, but is not limited to, a dimension of 100 mm or more and 300 mm or less.

A plurality of spokes 40 connect the inner annular portion 20 and the outer annular portion 30. The inner annular portion 20 and the outer annular portion 30, connected by the plurality of spokes 40, are arranged concentrically with each other. Each of the plurality of spokes 40 is arranged independently along the tire circumferential direction C. As shown in FIG. 1, when the non-pneumatic tire 1 is in an unloaded state, the plurality of spokes 40 extend linearly in the radial direction, approximately parallel to the tire radial direction X, in a side view.

As shown in Figures 4 and 5, the multiple spokes 40 in this embodiment include multiple first spokes 41 and multiple second spokes 42. The extension direction of both the first spokes 41 and the second spokes 42 is not parallel to the tire radial direction X when viewed in the tire circumferential direction C. The first spokes 41 are inclined toward one side of the tire axial direction, i.e., the tire width direction Y. The second spokes 42 are inclined toward the opposite side from the first spokes 41. The first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction C.

More specifically, as shown in Figures 4 and 5, the first spoke 41 extends at an angle from the Y1 side, which is one side of the outer annular portion 30 in the tire width direction Y, toward the Y2 side, which is the other side of the inner annular portion 20 in the tire width direction Y. The second spoke 42 extends at an angle from the Y2 side, which is the other side of the outer annular portion 30 in the tire width direction Y, toward the Y1 side, which is one side of the inner annular portion 20 in the tire width direction Y.

The inclination angle of the first spoke 41 and the second spoke 42 is the same. Therefore, the first spoke 41 and the second spoke 42 adjacent to each other in the tire circumferential direction C are arranged in a substantially X-shape when viewed from a direction along the tire circumferential direction C. As shown in FIG. 4, the first spoke 41 and the second spoke 42 are inclined at an angle θ with respect to the tire width direction Y, and the angle θ is preferably, for example, between 30° and 60°.

As shown in Figure 4, the first spoke 41 and the second spoke 42 have the same shape and are symmetrical with respect to the tire equatorial plane E when viewed in the direction along the tire circumferential direction C. Therefore, in the following, when there is no need to distinguish between the first spoke 41 and the second spoke 42 and they can be described together, the first spoke 41 and the second spoke 42 will be collectively referred to as spoke 40.

The spokes 40 are plate-shaped and extend obliquely at the angle θ from the inner annular portion 20 toward the outer annular portion 30. As shown in FIG. 5, the thickness t of each spoke 40 along the tire circumferential direction is smaller than its width w, and the direction of the thickness t is aligned with the tire circumferential direction C. That is, the spokes 40 are formed in a plate shape extending in the tire radial direction X and tire width direction Y. Note that the width w here refers to the dimension in the direction perpendicular to the inclined direction in which the spokes 40 extend when viewed from the tire circumferential direction C, as also shown in FIG. 4. In this embodiment, all spokes 40 have the same thickness t. All spokes 40 also have the same width w.

Since the spokes 40 are long and plate-shaped, the durability of the spokes 40 can be improved by widening the plate width w even if the plate thickness t is thin. Furthermore, by reducing the plate thickness t and increasing the number of spokes 40, the spacing between adjacent spokes 40 in the tire circumferential direction C can be reduced while maintaining the rigidity of the non-pneumatic tire 1 as a whole. This distributes the ground contact pressure of the spokes 40 when the tire rolls, reducing the ground contact pressure.

In this embodiment, the spokes 40 are parallel to the tire radial direction X in side view, but the spokes 40 may also be arranged obliquely with respect to the tire radial direction X so as to intersect with the tire radial direction X in side view.

As shown in Figures 4 and 5, the first spoke 41 has a first inner connection portion 411 that connects to the tire width direction Y2 side of the inner annular portion 20, and a first outer connection portion 412 that connects to the tire width direction Y1 side of the outer annular portion 30. The second spoke 42 has a second inner connection portion 421 that connects to the tire width direction Y1 side of the inner annular portion 20, and a second outer connection portion 422 that connects to the tire width direction Y2 side of the outer annular portion 30. The first outer connection portion 412 and the second outer connection portion 422 are each an example of a connection portion of the spoke 40 that connects to the outer annular portion 30 in this embodiment.

As shown in FIG. 4 , the first inner connection portion 411 of the first spoke 41 has a shape that widens in the tire width direction Y as it approaches the inner annular portion 20. The side surface 411a of the first inner connection portion 411 on the tire width direction Y2 side extends in a gently curved manner to the end portion 20b of the inner annular portion 20 on the tire width direction Y2 side. The side surface 411b of the first inner connection portion 411 on the tire width direction Y1 side extends in a curved manner toward the tire width direction Y1 side to the position of the tire equatorial plane E of the inner annular portion 20.

The first outer connection portion 412 of the first spoke 41 has a shape similar to the first inner connection portion 411, and has a shape that widens in the tire width direction as it approaches the outer annular portion 30. The side surface 412a on the tire width direction Y1 side of the first outer connection portion 412 extends in a gently curved manner to the end portion 30a of the outer annular portion 30 on the tire width direction Y1 side. The side surface 412b on the tire width direction Y2 side of the first outer connection portion 412 extends in a curved manner toward the tire width direction Y2 side to the position of the tire equatorial plane E of the outer annular portion 30.

The first inner connection portion 411 is provided in half of the area of the inner annular portion 20 on the tire width direction Y2 side. The first outer connection portion 412 is provided in half of the area of the outer annular portion 30 on the tire width direction Y1 side.

As shown in FIG. 4 , the second inner connection portion 421 of the second spoke 42 has a shape that widens in the tire width direction Y as it approaches the inner annular portion 20. The side surface 421a of the second inner connection portion 421 on the tire width direction Y1 side extends in a gently curved manner to the end portion 20a of the inner annular portion 20 on the tire width direction Y1 side. The side surface 421b of the second inner connection portion 421 on the tire width direction Y2 side extends in a curved manner toward the tire width direction Y2 side to the position of the tire equatorial plane E of the inner annular portion 20.

The second outer connection portion 422 of the second spoke 42 has a shape similar to the second inner connection portion 421, and has a shape that widens along the tire width direction as it approaches the outer annular portion 30. The side surface 422a of the second outer connection portion 422 on the tire width direction Y2 side extends in a gently curved manner to the end portion 30b of the outer annular portion 30 on the tire width direction Y2 side. The side surface 422b of the second outer connection portion 422 on the tire width direction Y1 side extends in a curved manner toward the tire width direction Y1 side to the position of the tire equatorial plane E of the outer annular portion 30.

The second inner connection portion 421 is provided in half of the area of the inner annular portion 20 on the tire width direction Y1 side. The second outer connection portion 422 is provided in half of the area of the outer annular portion 30 on the tire width direction Y2 side.

As mentioned above, all spokes 40 in this embodiment have the same thickness t. While there are no particular limitations on the thickness t, it is preferable that the thickness t be between 1 mm and 30 mm, and more preferably between 5 mm and 25 mm, so that the spokes 40 can adequately withstand rotational forces from the inner annular portion 20 and the outer annular portion 30 while still being able to flex appropriately when subjected to a load.

As mentioned above, all spokes 40 in this embodiment have the same width w. There are no particular limitations on the width w of the spokes 40, but in order to be able to adequately withstand rotational forces from the inner annular portion 20 and the outer annular portion 30 while also being able to flex appropriately when subjected to a load, it is preferable that the width w be 5 mm or more and 25 mm or less, and more preferably 10 mm or more and 20 mm or less. Furthermore, from the perspective of being able to distribute ground pressure while improving durability, the width w is preferably 110% or more of the thickness t, and more preferably 115% or more.

The number of spokes 40 is preferably between 80 and 300, and more preferably between 100 and 200, from the perspective of being able to adequately support the load from the vehicle while also being lightweight and improving both power transmission and durability.

The spokes 40 can be made from the elastic materials listed below. First, in terms of the properties of the elastic material, in order to ensure adequate durability while providing appropriate rigidity, it is preferable that the tensile modulus calculated from the tensile stress at 10% elongation in a tensile test conducted in accordance with JIS K7312:1996 be 3 MPa or more and 12 MPa or less.

If the tensile modulus of a spoke 40 calculated from the tensile stress at 10% elongation is less than 3 MPa, sufficient rigidity will not be obtained, and there is a possibility that adjacent spokes 40 in the tire circumferential direction C will come into contact with each other. On the other hand, if the tensile modulus calculated from the tensile stress at 10% elongation exceeds 12 MPa, the rigidity will be excessively high, resulting in a poor ride.

Elastic materials that can be used as the base material for the spokes 40 include thermoplastic elastomers, cross-linked rubber, and other resins.

Examples of thermoplastic elastomers include polyester elastomers, polyolefin elastomers, polyamide elastomers, polystyrene elastomers, polyvinyl chloride elastomers, and polyurethane elastomers.

The rubber material that makes up the crosslinked rubber can be either natural or synthetic rubber. Examples of synthetic rubber include styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IIR), nitrile rubber (NBR), hydrogenated nitrile rubber (hydrogenated NBR), chloroprene rubber (CR), ethylene propylene rubber (EPDM), fluororubber, silicone rubber, acrylic rubber, and urethane rubber. Two or more of these rubber materials may be used in combination as needed.

Other resins include thermoplastic resins and thermosetting resins. Thermoplastic resins include polyethylene resin, polystyrene resin, and polyvinyl chloride resin. Thermosetting resins include epoxy resin, phenolic resin, polyurethane resin, silicone resin, polyimide resin, and melamine resin.

Of the above elastic materials, urethane resin is preferably used for the spokes 40 from the standpoints of moldability, processability, and cost. However, foamed materials can also be used as the elastic material. That is, foamed materials made from the above-mentioned thermoplastic elastomers, cross-linked rubber, and other resins can be used.

The elastic material used as the base material of the spokes 40 may be reinforced with reinforcing fibers. Examples of reinforcing fibers include long fibers, short fibers, woven fabrics, and nonwoven fabrics. Examples of reinforcing fibers include rayon cords, polyamide cords such as nylon-6,6, polyester cords such as polyethylene terephthalate, aramid cords, glass fiber cords, carbon fiber cords, and steel cords.

Note that the reinforcement of the elastic material is not limited to reinforcement with reinforcing fibers. For example, reinforcement may be achieved by adding granular fillers. Examples of granular fillers that can be added include ceramics such as carbon black, silica, and alumina, as well as fillers made of other inorganic materials.

The inner annular portion 20 and outer annular portion 30 are preferably formed from the same resin material as the spokes 40. In this case, the inner annular portion 20, outer annular portion 30, and spokes 40 can be integrally molded, for example, by a cast molding method.

The tread 50 is provided on the outer peripheral surface of the outer annular portion 30 and constitutes the outermost peripheral portion of the non-pneumatic tire 1. The tread 50 is formed by vulcanization bonding the support structure 10 and a tread rubber composition. The tread 50 has a tread surface 51 on its outer peripheral surface that comes into contact with the road surface. The tread surface 51 of the tread 50 is provided with a tread pattern formed of multiple grooves and land areas, similar to that of a conventional pneumatic tire.

The tread 50 may also be constructed by laminating multiple vulcanized rubber layers with different compositions and properties (for example, two or three layers).

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and the above embodiment may be modified as appropriate within the scope of the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Non-pneumatic tire 10 Support structure 20 Inner annular portion 20a, 20b End portion 30, 30A Outer annular portion 30a, 30b End portion 31 First colored layer 32 Reinforcing layer 33 Second colored layer 34 Third colored layer 40 Spokes 41 First spokes 42 Second spokes 411 First inner connection portion 411a, 411b Side surface 412 First outer connection portion 412a, 412b Side surface 421 Second inner connection portion 421a, 421b Side surface 422 Second outer connection portion 422a, 422b Side surface 50 Tread 51 Ground contact surface C Tire circumferential direction E Tire equatorial plane O Axial center X Tire radial direction Y Tire width direction

Claims (3)

A non-pneumatic tire comprising: a support structure; and a tread located radially outward of the support structure and extending along a tire circumferential direction,
the support structure includes an inner annular portion, an outer annular portion that is disposed coaxially with the inner annular portion and outward in the tire radial direction from the inner annular portion and that contains a resin, and a plurality of spokes that connect the inner annular portion and the outer annular portion and are arranged along the tire circumferential direction,
the outer annular portion includes a first colored layer extending along the tire circumferential direction and indicating a polishing limit, and a reinforcing layer provided radially inward of the first colored layer and extending along the tire circumferential direction ,
A non-pneumatic tire, wherein the distance between the first colored layer and the reinforcing layer is 1 mm or more . The non-pneumatic tire of claim 1, wherein the outer annular portion further comprises at least one colored layer radially outward of the first colored layer, the colored layer being different from the first colored layer and extending circumferentially along the tire. The non-pneumatic tire according to claim 2, wherein the first colored layer and the at least one colored layer are exposed in the tire width direction.