Overview
ISO/TR 16377:2012 is a Technical Report that provides consensus clarifications to ISO 28580:2009 (methods for measuring rolling resistance of passenger car, truck and bus tyres - single point test and correlation). The document is informative guidance only: its clarifications are intended to help test laboratories and manufacturers apply ISO 28580 consistently and are expected to inform future revisions of the standard.
Key topics and requirements
- Scope and status: Clarifications are limited to items where consensus existed; other suggested changes were excluded pending further work.
- Terminology: Adds the definition candidate machine (machine intended to measure new test tyres aligned to a reference machine) and refines deviation of alignment tyre as the time-based difference versus mean rolling resistance after drift correction.
- Tyre size classification: Replaces ambiguous “larger/smaller truck and bus tyres” with Load Index (LI) thresholds: LI ≤ 121 for smaller (including passenger car and small truck/bus) and LI > 121 for larger truck and bus tyres.
- Test conditions and tables: Clarifies table headings (e.g., “Truck and bus (including C, LT)”) and corrects footnote placement for inflation pressure vs. load; aligns wording with ISO 4000‑1 / 4209‑1 to indicate maximum single-tyre load-carrying capacity.
- Test procedure details: Practical wording fixes (e.g., remove tyre while running above test speed), and a note that force method measurements include bearing and aerodynamic losses of the wheel and tyre.
- Parasitic loss calculation: Distinguishes parasitic parameters (recommended subscript “p”) and provides formulas and method-specific clarifications for parasitic loss using force, torque and power measurement methods.
- Laboratory monitoring / repeatability:
- Laboratories operating reference or candidate machines must comply with ISO/TS 16949 or ISO/IEC 17025.
- Monitoring interval: no greater than one month, with a minimum of three measurements per month to evaluate drift and repeatability.
- Reference machine target: σ ≤ 0.05 N/kN (control tyre).
- Candidate machine targets: σ ≤ 0.075 N/kN for passenger car/small truck & bus (LI ≤ 121) and σ ≤ 0.060 N/kN for larger truck & bus (LI > 121). If not met, the TR provides a formula to calculate the minimum number of measurements required.
Applications
- Harmonizing rolling resistance testing across laboratories and manufacturers.
- Qualifying and aligning candidate machines to a reference machine for inter-lab comparability.
- Improving measurement repeatability and traceability for compliance, R&D, fuel-efficiency labeling, and OEM validation.
- Clarifying procedural and reporting details needed for consistent test data used in tyre development and regulatory submissions.
Who should use this
- Tyre manufacturers and test engineers
- Independent tyre test laboratories and accreditation bodies
- Automotive OEMs and procurement teams validating tyre performance
- Standards committees and technical working groups involved in tyre testing
Related standards
