ISO 3911:2021

Overview

ISO 3911:2021 - Wheels and rims for pneumatic tyres - Vocabulary, designation and marking - defines a common vocabulary and a worldwide system for the designation and marking of wheels and rims intended for use with pneumatic tyres. The standard sets out fundamental terms (wheel, rim, disc, inset/zeroset/outset, bead seat, well, etc.), wheel and rim type definitions (disc, divided, wire, demountable, multi‑piece, adjustable), and the specifications for size designation and marking (content, location and minimum size) to establish a uniform identification system on a global basis.

Key topics

• Vocabulary and nomenclature
  • Clear definitions for wheel components: rim, disc, inset/zeroset/outset, dual wheel, bead seat, flange, well, valve aperture.
  • Illustrative figures and nomenclature (Figures 1–15) for passenger, commercial and special wheels.
• Rim and wheel types
  • One‑piece, two‑piece, three‑piece, four‑piece, five‑or‑more‑piece rims; disc, divided, wire, demountable and adjustable wheels.
  • Optional bead seat profiles (RH, SL, FH, CH, H2) and mounting bevel descriptions.
• Size designation system
  • Preferred order: nominal rim diameter (in size code or millimetres for new‑concept tyres), rim type symbol (“x” for one‑piece, “–” for multi‑piece), nominal rim width, and rim profile letters (e.g., B, J).
• Marking requirements
  • Content to be marked on disc wheels, demountable rims, rings and divided wheels.
  • Minimum size, location, legibility and additional marking considerations (offset/inset/outset marking).
• Edition notes
  • Fourth edition (2021) replaces ISO 3911:2004 and includes updates such as added optional bead seat profiles, revised multi‑piece rim definitions and extended designation/marking options.

Applications

ISO 3911:2021 is practical for:

• Wheel and rim manufacturers - standardizes terminology, marking and size codes to support design, production and quality control.
• Automotive and commercial vehicle engineers - ensures consistent specification and interchangeability of wheel assemblies.
• Aftermarket suppliers and fitters - helps identify correct replacement wheels/rims and ensures safe tyre mounting.
• Regulatory bodies and testing labs - supports traceability, compliance checks and international trade documentation.
• Fleet operators and maintenance teams - improves safety by clarifying offset/inset/outset and wheel matching.

Using ISO 3911 improves safety, compatibility and traceability of wheel and rim products across markets and supply chains.

Related information

• Prepared by ISO/TC 22 (Road vehicles), Subcommittee SC 33 (Vehicle dynamics and chassis components).
• For full text, figures and detailed marking rules consult the official ISO 3911:2021 publication or the ISO Online Browsing Platform.