Overview
ISO/TS 11819-3:2021 - Acoustics: Measurement of the influence of road surfaces on traffic noise - Part 3: Reference tyres specifies two reference tyres for use with the close-proximity (CPX) method (ISO 11819-2). The technical specification defines tyre identification, geometry, tread condition, hardness measurement, mounting and run-in procedures, and required corrections (rubber hardness and temperature) so CPX measurements of tyre/road noise are reproducible and representative of passenger‑car and heavy‑vehicle behaviour.
Key topics and requirements
- Reference tyres: Two tyres are defined:
- P1 - steel-belted radial, dimensional code P225/60R16 (Standard Reference Test Tyre).
- H1 - steel-belted reinforced radial, 195R14C (Avon Supervan AV4 used as H1).
- Markings & traceability: Sidewall markings must show product ID and production week/year (WWYY).
- Tread pattern & depth: Specified geometric patterns and initial tread depths: P1 = (8.0 ± 0.5) mm, H1 = (10.0 ± 0.5) mm; unacceptable misaligned patterns for H1 are identified.
- Rubber hardness: Measured in Shore A units (Type A durometer, ISO 868). A rubber hardness coefficient (βt) is used to correct CPX levels for hardness variations; the 2021 edition updates this coefficient.
- Test wheel, mounting, run‑in, load & inflation: Requirements ensure consistent tyre mounting and conditioning before CPX testing.
- Corrections & uncertainty:
- Procedures to correct CPX levels for rubber hardness and temperature (referencing ISO/TS 13471-1).
- Measurement uncertainty assessment following ISO/IEC Guide 98-3 (GUM).
- Documentation & annexes: Includes normative annex on hardness measurement and informative annexes on tyre storage, availability, and selection guidance.
Practical applications and users
ISO/TS 11819-3:2021 is essential for organizations conducting objective road surface acoustic evaluations where tyre/road noise dominates. Typical users:
- Road planners, road authorities and contractors assessing or specifying low-noise surfaces.
- Acoustic laboratories and test facilities performing CPX method measurements.
- Pavement engineers and researchers comparing surface designs or long-term surface performance.
- Vehicle and tyre manufacturers seeking stable reference tyres for comparative testing, or to verify tyre noise characteristics.
- Agencies performing rolling resistance or fuel-consumption tests that require defined tyre reference conditions.
Related standards
- ISO 11819-2 (CPX method)
- ISO/TS 13471-1 (temperature correction for CPX)
- ISO 4000-1 (tyre dimensions)
- ISO 868 (Shore A hardness)
- ISO/IEC Guide 98-3 (GUM - uncertainty)
- Reference use in UN ECE R117 and ISO 10844 contexts is noted for related testing needs.
Keywords: ISO/TS 11819-3:2021, CPX method, reference tyres, tyre/road noise, P1, H1, Shore A, rubber hardness, road surface acoustics.