Overview
ISO 13328:2000 - "Motorcycle tyres - Measurement of tyre rolling circumference - Loaded new tyres" defines a laboratory method to measure the rolling circumference and revolutions per kilometre for new motorcycle and moped tyres under loaded conditions. The standard provides a reproducible drum-test procedure to produce reference rolling-circumference values that support tyre sizing, speedometer/odometer calibration and comparative testing. Values obtained are for reference and are not intended as performance or quality limits.
Key topics and technical requirements
- Test principle: A test tyre mounted on a free axle is loaded against a driven road wheel (laboratory drum) and run at a specified constant speed while tyre and drum revolutions are counted.
- Reference drum: Standard laboratory drum diameter = (1.7 ± 0.017) m. Load correction factor 0.885 is applied for this drum radius; other drums between 1.5 m and 3 m require corresponding correction factors.
- Environmental and speed conditions:
- Ambient temperature: (25 ± 5) °C (no temperature correction required).
- Test speed: (80 ± 0.5) km/h for tyres with speed symbol above “L”; (50 ± 0.5) km/h for “L” and below.
- Tyre conditioning and warm-up:
- Conditioning run: 1 hour at specified speed, load and inflation.
- Warm-up on drum: ~30 minutes; then run with capped pressure for test.
- Loads and inflation:
- Test load: computed as a percentage of tyre maximum load (65% for light/standard load; 80% for reinforced/extra load), within ±20 N tolerance.
- Inflation pressure: (200 ± 3) kPa (light/standard); (250 ± 3) kPa (reinforced).
- Measurement accuracy and repetition:
- Minimum 10 impulses per revolution for both tyre and drum counters.
- Overall counting error ≤ 0.1%.
- Revolutions counted during 2-minute runs; two runs required with agreement within 0.2%, otherwise repeat.
- Results:
- Rolling circumference is derived from averaged drum and tyre revolution counts and the drum radius.
- Revolutions per kilometre = 1,000,000 / C (where C is circumference in millimetres).
Applications and users
- Tyre manufacturers and R&D labs: to establish reference rolling-circumference data for product documentation.
- Test laboratories and certification bodies: repeatable procedure for comparative measurement.
- Motorcycle OEMs and instrument suppliers: support speedometer calibration and odometer accuracy adjustments, especially since many instruments are driven from the front wheel.
- Regulators and fleet operators: reference data for regulatory compliance checks and fleet telematics calibration.
- Researchers studying tyre geometry, rolling behavior, or vehicle speed measurement.
Related standards
- Normative reference: ISO 4223-1 (definitions for tyre industry terms).
- Bibliography includes related motorcycle/moped tyre and rim standards (e.g., ISO 4249, ISO 5751, ISO 5995), useful for rim selection, load ratings and dimensional references.
Keywords: ISO 13328:2000, motorcycle tyres, tyre rolling circumference, revolutions per kilometre, tyre measurement, drum test, speedometer calibration, odometer accuracy, tyre test method.
