Tire

Abstract

Provided is a tire in which a decrease in durability is suppressed while using a steel wire derived from regenerated iron. In order to solve the problem, the present invention provides a tire which comprises a carcass layer containing steel cords, and which is characterized in that: the steel cords comprise steel wires; 20% by mass or more of the steel wire is derived from regenerated iron; and the amount of elemental N in the steel wire derived from the regenerated iron is 60 ppm by mass or more.

Description

Technical Field

[0001] This disclosure relates to a tire. Background Technology

[0002] In recent years, from the perspective of resource recycling, it is necessary to use recycled materials in various components used in tires. For example, Patent Document 1 mentions the use of organic fibers from recycled sources, particularly fibers made from recycled polyethylene terephthalate (PET) as reinforcing components of tires.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: EP 3753965 A1 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] On the other hand, in addition to organic fibers, steel cord is also used as a reinforcing component in tires. Therefore, from the perspective of resource recycling, there is a need to use steel cord made from steel derived from recycled iron.

[0008] However, steel cord derived from scrap iron or tires may contain coating materials such as plating and various additives, which are often included as impurities in the recycled iron. Compared to regular steel wire, steel wire (wire material) made from such recycled iron may have lower strength, and when steel cord made from recycled iron is used as a reinforcing member in the tire's reinforcing layer, it must be designed so as not to affect the tire's durability.

[0009] Therefore, this disclosure solves the aforementioned conventional problems, and its object is to provide a tire in which the reduction of durability is suppressed even when steel wire derived from recycled iron is used.

[0010] Solutions for solving problems

[0011] The key features of the tire disclosed herein that solve the above problems are as follows.

[0012] [1] A tire comprising a carcass layer including steel cords, wherein

[0013] Steel cord contains steel wires, with over 20% by weight of the steel wires derived from recycled iron.

[0014] The nitrogen content of the wire derived from recycled iron is above 60 ppm by mass.

[0015] The tire disclosed herein, as described in [1], suppresses the reduction in durability even when steel wire derived from recycled iron is used.

[0016] [2] According to the tire described in [1], the steel wire derived from recycled iron has a C content of 0.7 to 1.0 by mass, a Cu content of 0.01 to 0.4 by mass, and a Cr content of 0.05 to 0.3 by mass.

[0017] From an environmental point of view, the tire described in [2] is preferred because it uses steel cords that can be made from common recycled iron.

[0018] [3] According to the tire described in [2], the Cu content of the steel wire derived from recycled iron is 0.05 to 0.4 by mass.

[0019] From an environmental point of view, the tire described in [3] is also preferred because it uses steel cords that can be made from common recycled iron.

[0020] [4] The diameter of the steel wire derived from recycled iron in any one of [1] to [3] is 0.15 to 0.40 mm.

[0021] The tire described in [4] is designed to make the steel wires difficult to break and to have high durability.

[0022] [5] In any one of [1] to [4], the steel cord further comprises steel wires derived from non-recycled iron, and

[0023] The steel wire derived from non-recycled iron contains 20 to 40 ppm N, 0.7 to 0.85 ppm C, 0 to 0.1 ppm Cu, and 0 to 0.1 ppm Cr.

[0024] The tires described in [5] are designed to further suppress the reduction in durability.

[0025] [6] The tire according to any one of [1] to [5], wherein the steel wire derived from recycled iron is provided with a coating, and The Cu content in the steel wire and coating derived from recycled iron is 0.2 to 1.0% by mass.

[0026] The tires described in [6] have improved durability.

[0027] The effects of the invention

[0028] According to this disclosure, a tire in which the reduction of durability is suppressed even when steel wire derived from recycled iron is provided. Attached Figure Description

[0029] In the attached diagram:

[0030] [Figure 1 [A cross-sectional view showing one embodiment of the tire of this disclosure.] Detailed Implementation

[0031] In the following sections, the tires disclosed herein will be illustrated and described in detail based on their implementations.

[0032] <Definition>

[0033] The compounds described in this specification may be derived in whole or in part from fossil resources, from biological resources such as plant resources, or from renewable resources such as waste tires. Furthermore, they may be derived from any mixture of two or more of fossil resources, biological resources, and renewable resources.

[0034] In this specification, the N (nitrogen), C (carbon), Cu (copper), Cr (chromium), and Fe (iron) content of steel wire derived from recycled iron and steel wire derived from non-recycled iron, as well as the Cu content in steel wire derived from recycled iron and the entire coating, refer to the ladle value (i.e., the ladle value measured for molten steel) in the molten state of the raw steel, and are values ​​measured by spark discharge luminescence spectrophotometry.

[0035] <Tires>

[0036] The tire in this embodiment includes a carcass ply (carcass cord ply) containing steel cords.

[0037] In the tire of this embodiment, the steel cord contains steel wires, of which more than 20% by mass is derived from recycled iron, and the wires derived from recycled iron are characterized by having an N element content of more than 60 ppm by mass.

[0038] The tire of this embodiment includes a carcass ply containing steel cords, the steel cords containing steel wires, and more than 20% by mass of the total mass of the steel wires in the carcass ply originates from recycled iron.

[0039] When the proportion of steel wire derived from recycled iron in the entire steel cord of the tire carcass is more than 20% by mass, resources can be fully recycled while inhibiting the reduction of tire carcass durability.

[0040] There are no particular restrictions on the recycled iron used as raw material for steel wire derived from recycled iron, as long as it is recycled, and it can be derived from, for example, scrap iron or steel cord taken from tires. Furthermore, from the viewpoint of reducing CO2 emissions, it is preferable that the recycled iron originates from an electric arc furnace (electric arc furnace steelmaking). In electric arc furnace steelmaking, for example, an electric arc discharge is generated in the electric furnace, the raw material is melted by the heat of the discharge, impurities are removed, and iron (steel) is obtained. On the other hand, in the blast furnace method, which is commonly used in conventional steelmaking, for example, coke derived from coal is used in the blast furnace to reduce iron ore to obtain iron (steel), thus inevitably generating a large amount of CO2. Typically, CO2 emissions from an electric arc furnace are about one-quarter of those from a blast furnace; therefore, by using recycled iron from an electric arc furnace for steel wire, CO2 emissions can be significantly reduced.

[0041] In the tires of this embodiment, the N (nitrogen) content of the steel wire derived from recycled iron needs to be above 60 ppm by mass.

[0042] Typically, virgin iron, such as iron obtained from blast furnaces, has high purity and a nitrogen (N) content of less than 60 ppm by mass, while ordinary recycled iron (i.e., unrefined recycled iron) has an N content of 60 ppm by mass or more. Steel wire derived from recycled iron can be produced using this ordinary recycled iron as raw material, and because it does not require high refining, the manufacturing process is simple, reducing energy consumption and CO2 emissions, which is preferable from an environmental perspective. Similarly, it is preferable that the N content of steel derived from recycled iron is 70 ppm by mass or more.

[0043] Furthermore, from a durability point of view, it is preferable that the nitrogen content of the steel wire derived from recycled iron is less than 200 ppm by mass, more preferably less than 90 ppm by mass. It should be noted that the reinforcing cords of the tire carcass are subjected to loads from various directions during tire manufacturing and use. Therefore, as an indicator of durability, the steel wires constituting the reinforcing cords of the tire carcass need to have excellent torsional durability. Steel wires made from steel derived from recycled iron with a nitrogen content of less than 90 ppm by mass exhibit particularly excellent torsional durability.

[0044] Furthermore, it is preferable that the carbon (C) content of the steel wire derived from recycled iron is 0.7 to 1.0% by mass, more preferably 0.7 to 0.85% by mass. Recycled iron with a C content within the above range does not require high refining, is readily available, and steel wire with a C content within the above range can be produced from ordinary recycled iron. In addition, recycled iron (steel) with a C content of 0.85% by mass or less has high ductility and can prevent breakage even when processed into small-diameter steel wires. Therefore, in tires using steel wire derived from recycled iron with a C content of 0.7 to 0.85% by mass, the steel wire is less prone to breakage and has high durability.

[0045] Furthermore, it is preferred that the Cu (copper) content of the steel wire derived from recycled iron is 0.01 to 0.4% by mass, more preferably 0.05 to 0.4% by mass. Recycled iron with a Cu content within the above range does not require high refining and is readily available, and steel wire with a Cu content within the above range can be produced from ordinary recycled iron.

[0046] Furthermore, it is preferred that the Cr (chromium) content of the steel wire derived from recycled iron is 0.05 to 0.3% by mass. Recycled iron with a Cr content within the above range does not require high refining, is readily available, and steel wire with a Cr content within the above range can be produced from ordinary recycled iron.

[0047] The steel wire derived from recycled iron needs to have an N (nitrogen) content of at least 60 ppm by mass, and preferably, a C content of 0.7 to 1.0% by mass, a Cu content of 0.05 to 0.4% by mass, and a Cr content of 0.05 to 0.3% by mass. This steel wire can be produced using common recycled iron as raw material, and because it does not require high refining, the manufacturing process is simple and energy consumption can be reduced. Furthermore, CO2 emissions can also be reduced, making it preferred from an environmental perspective.

[0048] It should be noted that steel wire derived from recycled iron preferably has iron as its main component, with the Fe (iron) element content being 98% by mass or more.

[0049] Preferably, the diameter of the steel wire derived from recycled iron is between 0.15 mm and 0.40 mm. When the diameter of the steel wire derived from recycled iron is 0.15 mm or more, it exhibits excellent strength and durability, and is unlikely to break during the drawing process. Furthermore, when the diameter of the steel wire derived from recycled iron is less than 0.40 mm, the wire can conform to the deformation of the tire, is less prone to breakage, and also has the advantage of being lightweight. In other words, tires using steel wire derived from recycled iron with a diameter of 0.15 mm to 0.40 mm have high durability.

[0050] Steel wire derived from recycled iron is made from recycled iron, and there are no particular restrictions on the manufacturing method. For example, steel derived from scrap iron or steel cord taken from tires can be drawn to produce steel wire derived from recycled iron.

[0051] Preferably, the steel wire derived from recycled iron is provided with a coating covering the steel wire.

[0052] Preferably, the Cu content in the steel wire and the entire coating is 0.2 to 1.0% by mass. It should be noted that the Cu content refers to the Cu content in the entire steel wire portion and coating portion derived from recycled iron.

[0053] When the Cu content in the steel wire derived from recycled iron and the entire coating is 0.2% by mass or more, the quality of the rubber-steel bond can be ensured; and when it is 1.0% by mass or less, the quality of the steel wire can be ensured. When the Cu content in the steel wire derived from recycled iron and the entire coating is between 0.2% and 1.0% by mass, the adhesion between the steel wire derived from recycled iron and the coated rubber is high, and the durability of the tire is improved.

[0054] For example, a coating can be applied by plating the surface of steel wire derived from recycled iron. Examples of such plating include brass plating and copper plating, with brass plating being preferred from the viewpoint of adhesion to coated rubber. In brass plating, the ratio of copper to zinc (copper:zinc) is preferably in the range of 60:40 to 70:30 by mass.

[0055] The steel cord in the carcass ply may further comprise steel wires derived from non-recycled iron, and preferably, the non-recycled iron steel wires have a nitrogen (N) content of 20 to 40 ppm by mass, a carbon (C) content of 0.7 to 0.85% by mass, a copper (Cu) content of 0 to 0.1% by mass, and a chromium (Cr) content of 0 to 0.1% by mass. When the steel cord in the carcass ply comprises non-recycled iron steel wires with this composition, the reduction in the durability of the steel cord can be further suppressed, and the reduction in tire durability can be further suppressed. It should be noted that the non-recycled iron steel wires preferably have iron as the main component, wherein the iron (Fe) content is 98% by mass or more.

[0056] There are no particular restrictions on the diameter of steel wire derived from non-recycled iron, and it can be the same as or different from the diameter of steel wire derived from recycled iron.

[0057] Furthermore, it is preferable that the steel wire derived from non-recycled iron has a coating covering the steel wire. The coating of the steel wire derived from non-recycled iron may be the same as or different from the coating of the steel wire derived from recycled iron.

[0058] From the viewpoint of the durability of steel wire cord, it is preferable to use non-recycled iron with fewer impurities as the raw material for steel wire cord, and for example, iron derived from iron ore (iron derived from blast furnace) is preferred.

[0059] When the diameter of the steel wire constituting the carcass layer is X (mm) and the tensile strength of the wire is Y (MPa), the following formula is preferably satisfied:

[0060] 4000-2000X≤Y≤4500-2000X

[0061] By using cords in the carcass ply with a structure in which the fibers satisfying the above formula are twisted together, the strength of the carcass ply can be improved, the puncture level can be improved, and the tire's cut resistance can be supplemented.

[0062] Here, the tensile strength of the filament is determined according to ISO 17832:2009.

[0063] From a fatigue resistance point of view, it is preferable that the hardness of the outer layer of the cord fibers constituting the carcass layer is 90 to 110% relative to the hardness of the inner layer, particularly preferably 100%. Hardness can be measured, for example, by Vickers hardness. The outer layer of the fiber refers to the layer from the outermost surface to a depth of 0.01 mm, and the inner layer refers to the inner layer of the fiber. For the outer layer, hardness can be measured at a depth from the outermost surface to 0.005 mm, and for the inner layer, it can be measured at a depth greater than 0.04 mm.

[0064] In the tire of this embodiment, there are no particular restrictions on the configuration of steel wires derived from recycled iron. For example, (1) a steel cord consisting of steel wires derived from recycled iron and steel wires derived from non-recycled iron can be configured in the same carcass layer, or (2) a carcass layer consisting of steel cords composed of steel wires derived from recycled iron and a carcass layer consisting of steel cords composed of steel wires derived from non-recycled iron can be separately configured. In either mode, the steel wires derived from non-recycled iron can supplement the strength of the steel wires derived from recycled iron and suppress the reduction of tire durability.

[0065] There are no particular restrictions on the structure of the steel cords that make up the carcass layer, but examples include:

[0066] (1) Layered twist structure, such as L+M structure or L+M+N structure, wherein M or M+N sheath filaments (where M and N are integers greater than 1) are twisted around L core filaments (where L is an integer greater than 1; the core filaments can be twisted together or bundled without twisting).

[0067] (2) Compact structure, in which multiple steel wires are twisted together in the same direction and at the same pitch.

[0068] (3) Multi-twisted structure, wherein multiple cords of the above-mentioned layered twisted structure or dense structure are twisted together.

[0069] (4) In which one filament is further wound around the outermost periphery of the cord with the above-mentioned layered twist structure, dense structure or multi-twist structure.

[0070] etc.

[0071] The strands that make up the steel cord can be spaced apart so that they are not in close contact with each other. In this structure, rubber can easily penetrate into the interior of the cord, thereby improving the cord's durability.

[0072] Furthermore, the surface of the steel wire or the steel cord can be coated with resin. This structure improves the durability of the steel cord. Examples of resins include thermoplastic resins and thermoplastic elastomers. Examples of thermoplastic resins include polyamide-based thermoplastic resins, polyester-based thermoplastic resins, olefin-based thermoplastic resins, polyurethane-based thermoplastic resins, polyvinyl chloride-based thermoplastic resins, and polystyrene-based thermoplastic resins. On the other hand, examples of thermoplastic elastomers include polyamide-based thermoplastic elastomers (TPA), polyester-based thermoplastic elastomers (TPC), polystyrene-based thermoplastic elastomers (TPS), polyurethane-based thermoplastic elastomers (TPU), olefin-based thermoplastic elastomers (TPO), thermoplastic rubber vulcanizates (TPV), or other thermoplastic elastomers (TPZ).

[0073] The strength of the carcass layer is preferably above 20 kN, and more preferably below 250 kN. When the strength of the carcass layer is above 20 kN, the tire's durability is improved, and when the strength of the carcass layer is below 250 kN, both durability and weight can be achieved.

[0074] It should be noted that in this specification, the strength of the carcass layer is measured by tensile testing and converted into a value of strength per 5 cm.

[0075] The tire of this embodiment can be used on various vehicles and all types of tires, such as passenger car tires, truck and bus tires, large tires for construction vehicles, and motorcycle tires. Furthermore, the tire of this embodiment can be a pneumatic tire or a non-pneumatic tire.

[0076] (An implementation plan)

[0077] Next, an embodiment of the tire of this disclosure will be illustrated and described in detail with reference to the accompanying drawings.

[0078] Figure 1 This is a cross-sectional view of one embodiment of the tire disclosed herein. Figure 1 The tire 100 shown includes: a pair of bead portions 10; a pair of sidewall portions 20; a tread portion 30; a carcass 50 extending in a ring between bead cores 40 embedded in the bead portions 10; a belt 60 consisting of two belt layers 60A and 60B disposed in the tread portion 30 (more specifically, disposed on the outer side of the crown portion of the carcass 50 in the radial direction of the tire); a belt protection layer (also called a "crown layer") 70A disposed on the outer side of the belt 60 in the radial direction of the tire in a manner that covers the entire belt 60; and a pair of belt protection layers (also called "edge crown layers") 70B disposed in a manner that covers only the two ends of the belt protection layer 70A.

[0079] exist Figure 1 In the tire 100 shown, the carcass 50 is composed of one or more carcass plies and includes a main body extending in an annular shape between a pair of bead cores 40 respectively embedded in the bead portion 10, and a turn-up portion that is wound radially outward from the inside to the outside in the tire width direction around each bead core 40.

[0080] It should be noted that the number and structure of the carcass plies in the tires disclosed herein are not limited thereto. Here, the carcass plies constituting the carcass 50 are preferably formed by multiple reinforcing cords coated with coated rubber and extending in a direction substantially perpendicular to the tire circumferential direction (e.g., extending at an angle of 70 to 90°), that is, the carcass 50 is preferably a radial carcass. As reinforcing cords of the carcass 50, in addition to organic fiber cords such as polyethylene terephthalate cords, nylon cords, and rayon cords, steel cords may also be used.

[0081] also, Figure 1 The belt 60 of the tire 100 shown is composed of two belt layers 60A and 60B, and each belt layer 60A, 60B is generally formed by coating steel cords that extend at an angle (e.g., 15 to 40°) relative to the tire equator with coated rubber, and the belt 60 is formed by stacking the two belt layers 60A and 60B in such a way that the steel cords constituting the belt layers 60A and 60B cross each other across the tire equator.

[0082] It should be noted that, Figure 1 In this tire, the belt 60 is composed of two belt layers 60A and 60B. However, in the tire of this disclosure, the number of belt layers constituting the belt can be more than one, and is not limited thereto.

[0083] exist Figure 1In the tire 100 shown, belt protection layers 70A and 70B are formed by covering reinforcing cords arranged substantially parallel to the tire circumferential direction (e.g., at an angle of 0 to 5° relative to the tire circumferential direction) with coated rubber. Belt protection layers 70A and 70B are formed by continuously spirally winding a narrow strip prepared by covering the reinforcing cords with coated rubber in the tire circumferential direction. In this case, since there is no joint in the tire circumferential direction, the uniformity of the tire is improved, and since there is no joint, strain concentration at the joint is also prevented. As the reinforcing cords of belt protection layers 70A and 70B, organic fiber cords such as polyesters, including polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethylene furanate (PEF), and polyamides such as 6-nylon, can be used. ® 6,6-Nylon ® 4,6-Nylon ® Aromatic polyamides, and cellulose, such as rayon and lyocell.

[0084] There are no particular restrictions on the raw materials for organic fiber cords. They can be derived from synthetic products, biological resources such as plant, animal or microbial resources, mechanically recycled materials in which resin products are crushed, melted and respun, or chemically recycled materials in which resin products are depolymerized and repolymerized.

[0085] It should be noted that, although Figure 1 The tire 100 shown includes belt protection layers 70A and 70B, but a tire in which either or both of belt protection layers 70A and 70B are omitted is also an embodiment of the tire of this disclosure. Furthermore, in Figure 1 In the tire 100 shown, each belt protection layer 70A and 70B is a single layer, but two or more layers can be used.

[0086] In the carcass 50, belt 60 (belt layers 60A and 60B), and belt protective layers 70A and 70B, there are no particular restrictions on the coated rubber covering the reinforcing members (reinforcing cords), and various elastomers can be used.

[0087] The 50% modulus value of the elastomer, as measured according to JIS K 6251 (2010), is preferably 1.5 MPa or more, more preferably 1.8 MPa or more, and even more preferably 2.0 MPa or more.

[0088] As major components of elastomers, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR, high cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR and other diene rubbers and their hydrogenation products can be mentioned; ethylene-propylene rubber (EPDM, EPM), maleic acid modified ethylene-propylene rubber (M-EPM), butyl rubber (IIR), copolymers of isobutylene and aromatic vinyl or diene monomers, acrylic rubber (ACM), ionomers and other olefin rubbers; Br-IIR, Cl-IIR, brominated isobutylene-p-methylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), epichlorohydrin rubber (hydrin 50% modulus of elastomers (coated rubbers) including chlorosulfonated polyethylene rubber (CHR), chlorinated polyethylene rubber (CSM), maleic acid-modified chlorinated polyethylene rubber (M-CM), and other halogenated rubbers; methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber, and other silicone rubbers; polysulfide rubber and other sulfur-containing rubbers; vinylidene fluoride rubbers, fluorinated vinyl ether rubbers, tetrafluoroethylene-propylene rubbers, fluorosilicone rubbers, fluorophosphazene rubbers, and other fluororubbers; and thermoplastic elastomers such as styrene elastomers, olefin elastomers, ester elastomers, urethane elastomers, and polyamide elastomers. The 50% modulus value of the elastomer (coated rubber) is measured according to JIS K 6251 (2010) after the rubber composition of each sample has been vulcanized at 145°C for 40 minutes to obtain vulcanized rubber.

[0089] In addition to sulfur, vulcanization accelerators and carbon black, elastomers can be appropriately blended with anti-aging agents, zinc oxide (zinc white), stearic acid and other additives commonly used in rubber products such as tires.

[0090] Example

[0091] The present disclosure will now be described in more detail with reference to embodiments, but the present disclosure is not limited to the following embodiments.

[0092] (Test wire)

[0093] Steel wires 1 and 2, produced from recycled iron derived from an electric arc furnace, were prepared. Here, the nitrogen content of steel wire 1, measured by spark discharge atomic emission spectrometry, was 71 ppm by mass, and the nitrogen content of steel wire 2, measured by spark discharge atomic emission spectrometry, was 90 ppm by mass. The torsional durability of these steel wires was evaluated using the following method.

[0094] (Torsion test)

[0095] A 20cm long test steel wire was fixed at both ends and twisted by rotating it in one direction (clockwise relative to the axis of the wire) until the test steel wire broke. The total number of rotations at the point of breakage was measured and evaluated according to the following criteria. The results are shown in Table 1.

[0096] Excellent: The total number of rotations to fracture is more than 50.

[0097] Good: The total number of rotations to fracture is 20 to 49.

[0098] Defect: The total number of rotations to fracture is less than 19.

[0099] [Table 1]

[0100] Steel wire 1 Steel wire 2 Nitrogen content (ppm by mass) 71 90 Evaluation results of torsion test Excellent bad

[0101] As can be seen from Table 1, steel wire 1 with an N content of less than 90 ppm by mass has excellent torsional durability.

[0102] Description of Reference Numerals

[0103] 100: Tires

[0104] 10: Bead area

[0105] 20: Sidewall

[0106] 30: Tire face

[0107] 40: Tire bead core

[0108] 50: Fetus

[0109] 60: Belt

[0110] 60A, 60B: Belt layer

[0111] 70A, 70B: Belt protection layer

Claims

1. A tire comprising a carcass layer including steel cords, characterized in that, The steel wire cord comprises steel wires, and more than 20% by mass of the steel wires are derived from recycled iron. The nitrogen content of the wire derived from the recycled iron is above 60 ppm by mass.

2. The tire according to claim 1, wherein the steel wire derived from the recycled iron has a C content of 0.7 to 1.0% by mass, a Cu content of 0.01 to 0.4% by mass, and a Cr content of 0.05 to 0.3% by mass.

3. The tire according to claim 2, wherein the Cu element content of the steel wire derived from the recycled iron is 0.05 to 0.4% by mass.

4. The tire according to claim 1 or 2, wherein the diameter of the steel wire derived from the recycled iron is 0.15 to 0.40 mm.

5. The tire according to claim 1 or 2, wherein the steel cord further comprises steel wire derived from non-recycled iron, and The steel wire derived from non-recycled iron has an N content of 20 to 40 ppm by mass, a C content of 0.7 to 0.85% by mass, a Cu content of 0 to 0.1% by mass, and a Cr content of 0 to 0.1% by mass.

6. The tire according to claim 1 or 2, wherein the steel wire derived from the recycled iron is coated, and The Cu content in the steel wire derived from the recycled iron and the entire coating is 0.2 to 1.0 by mass.

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