Overview
ISO 7867-2:2018 - Metric series for agricultural, forestry machines and construction tyres - Part 2: Load ratings for agricultural tyres - defines how load ratings and reference inflation pressures are specified for metric-series tyres primarily intended for agricultural tractors, machines, equipment and their trailers. It applies to diagonal, bias‑belted and radial tyres mounted on 5° and 15° tapered rims. The document establishes the service description format (load index + speed symbol), tyre load‑carrying capacities for basic and special applications, and guidance on reference inflation pressures.
Key topics and technical requirements
- Service description: Tyres are marked with a load index and speed symbol (e.g., A6, A8, B, D). The standard gives the speed-symbol to km/h mapping for metric series tyres.
- Load index correlation: Load index values and corresponding capacities are referenced to ISO 4223-1 (Table A.1).
- Reference inflation pressure: The standard specifies reference inflation pressures associated with basic tyre loads and different tyre types (see annexes for tables of common sizes).
- Basic tyre load and reductions: Basic tyre load is the capacity at the speed indicated by the speed symbol. When used as duals or triples, tyre loads must be reduced to 88% and 82% of the basic tyre load respectively.
- Load/speed relationships: Tables define how allowable tyre load varies with service speed for drive and steering tyres and for different tyre technologies (standard metric, IF, VF). Manufacturers and rim/wheel makers must be consulted for pressure adjustments, especially at low speeds.
- Special service markings: Supplementary service descriptions (e.g., CHO, CFO) indicate allowed load/pressure adaptations for cyclic harvesting or field operations. Examples in the standard include:
- CHO (cyclic harvesting operations): specific load increases (e.g., 180% at 10 km/h; 165% at 15 km/h) with no inflation pressure increase.
- CFO (cyclic field operations) for IF tyres: defined load increases (e.g., 155% at 15 km/h; 130% at 30 km/h).
- Restrictions: IF/VF tyres used in combine service do not permit load or pressure increases unless specifically marked (CFO, etc.).
Practical applications
- Helps tyre manufacturers define and mark load ratings and service descriptions for metric agricultural tyres.
- Guides OEMs and tractor builders on tyre selection and wheel/tyre coordination for intended service (drive, steering, implement).
- Supports fleet managers and agricultural operators in selecting tyres and correct inflation pressures for field, transport and cyclic operations (combines, loaders).
- Used by standards bodies, regulators and certification bodies for compliance, labelling and safety verification.
Who should use this standard
- Tyre and rim manufacturers, agricultural OEMs, test laboratories, procurement specialists, safety engineers, and regulatory authorities involved in agricultural tyre performance, marking and load/pressure recommendations.
Related standards
- ISO 4223-1:2017 - Definitions and load index correlation
- ISO 7867-1 - Tyre size designation, marking and tyre/rim coordination
- ISO 18807 (forestry tyres) and ISO 13442 (construction/industrial tractors) - for forestry and construction tyre load ratings (outside the scope of ISO 7867-2).
Keywords: ISO 7867-2:2018, agricultural tyres, load ratings, metric series, reference inflation pressure, tyre load index, speed symbol, IF tyres, VF tyres, cyclic loading, combine harvesters.