ISO 4250-1:2023

Overview - ISO 4250-1:2023 (Earth‑mover tyres and rims - Part 1)

ISO 4250-1:2023 specifies the tyre designation and dimensional requirements for earth‑mover tyres and recommends the corresponding rims. Published as the seventh edition in April 2023, this standard applies primarily to tyres and rims intended for earth‑moving machinery defined in ISO 6165. It replaces the 2017 edition and harmonizes certain tyre size designations across the ISO 4250 series.

Key topics and technical requirements

ISO 4250-1 organizes requirements and markings related to tyre identity, sizing and in‑service dimensions. Major technical topics include:

• Tyre designation and sidewall markings

  • Mandatory information: size and construction characteristics, index of tyre strength.
  • Optional marking: operating condition (load index, speed symbol), usage codes and other service characteristics.

• Tyre size and construction

  • Codes for nominal section width and nominal aspect ratio (metric and legacy sizes).
  • Construction code: dash (–) for diagonal/bias tyres, R for radial (with optional “RADIAL” wording).
  • Nominal rim diameter code (linked to ISO 4250-3:2020) and specific suffixes (e.g., “TG”, “K”) for particular rim diameters.

• Index of tyre strength

  • Diagonal tyres: numerical ply rating (PR) (e.g., “16 PR”).
  • Radial tyres: symbol marking (stars).
  • Linkage to maximum recommended load and inflation pressure.

• Operating conditions

  • Load index table correlating numerical codes to tyre load‑carrying capacities.
  • Speed symbols and corresponding reference speeds (e.g., A2 = 10 km/h, B = 50 km/h, D = 65 km/h).
  • Usage indicators such as “CYCLIC” for limited continuous use.

• Other requirements

  • Preferred rotation arrow, “TUBELESS” marking, type of service and tread design codes.
  • Sections covering tyre dimensions, dual spacing, approved rims, and methods of measurement.

Practical applications - who uses ISO 4250-1

ISO 4250-1 is essential for:

• Tyre and rim manufacturers (design, marking, compatibility)
• Original equipment manufacturers (OEMs) of earth‑moving machinery
• Fleet and maintenance managers specifying replacement tyres and rims
• Test laboratories and conformity assessors verifying dimensional and marking compliance
• Standards writers, procurement teams and regulators ensuring safe load/speed matching

Using ISO 4250-1 ensures consistent tyre identification, proper rim selection, and safe tyre‑to‑load/speed matching across earth‑moving equipment fleets.

Related standards

• ISO 4250-2 - Earth‑mover tyres and rims: Loads and inflation pressures
• ISO 4250-3:2020 - Earth‑mover tyres and rims: Rims
• ISO 4223-1 - Definitions for tyre industry terms
• ISO 6165 - Classification/definition of earth‑moving machinery

Keywords: ISO 4250-1:2023, earth‑mover tyres, tyre designation, tyre dimensions, rims, load index, speed symbol, radial tyres, diagonal tyres, tyre marking.