Overview
ISO 16650:2004 - "Bead wire" - specifies the technical requirements, characteristics and delivery conditions for round and flat bead wire used to strengthen the bead of all kinds of tyres. The standard covers material selection, coating options, mechanical properties, dimensional tolerances, testing and inspection, marking and packaging. It applies to both normal tensile (NT) and high tensile (HT) bead wire grades and details designation and ordering practices (for example: Bead wire bronze‑coated ISO 16650‑HT‑1,295).
Key topics and technical requirements
- Material and classification
- Steel wire made from wire‑rod conforming to ISO 16120 series.
- Two tensile classes: NT (Normal tensile) and HT (High tensile).
- Coatings
- Metallic coatings allowed: brass, copper, low‑tin bronze, high‑tin bronze. Flat wire is only brass‑coated.
- Coating chemical composition and thickness tolerances are specified (e.g., brass, copper, bronze types; thickness values per coating type).
- Mechanical properties
- Tensile strength and minimum elongation specified by diameter and grade (tables define ranges for NT and HT).
- 0.2% proof strength (Rp0.2) must be at least 80% of the minimum tensile strength.
- Torsion resistance: minimum number of torsions by nominal diameter (e.g., 25, 22, 20 depending on size).
- Dimensions and surface
- Diameter tolerances and out‑of‑roundness limits; flat wire tolerances for width and thickness.
- Surface must be smooth and free of contaminants; residual torsion limits and straightness tests defined.
- Testing and inspection
- Requires tensile testing (ISO 6892), torsion testing (ISO 7800), chemical analysis, diameter/out‑of‑roundness measurement, adhesion testing (Annex A references ASTM D1871 method).
- Inspection documents and testing frequency follow ISO 10474/ISO 404.
- Delivery, marking and packaging
- Unit packages, spool and spoolless core options; marking for traceability (designation, heat number, weight, etc.).
Applications and users
- Primary use: reinforcement of the tyre bead in automotive, truck, motorcycle and specialty tyres.
- Typical users:
- Tyre manufacturers and compounders specifying bead wire for rubber adhesion and mechanical performance.
- Steel wire producers and wire‑rod converters manufacturing coated bead wire to customer orders.
- Quality, inspection and procurement engineers who specify testing protocols, certification and traceability.
- R&D teams validating bead‑to‑rubber adhesion and mechanical behaviour in tyre assemblies.
Related standards
Keywords: ISO 16650:2004, bead wire, tyre bead, tensile strength, brass‑coated, bronze‑coated, torsion test, adhesion test, tyre manufacturing.