Overview
ISO 5751-1:2010 - "Motorcycle tyres and rims (metric series) - Part 1: Design guides" provides design guidance, designation rules and the calculation methods for dimensions of metric-series motorcycle tyres. It applies to tyres with reduced height/width ratios (100 and lower) intended for cylindrical bead-seat or 5° tapered bead-seat rims, and can be extended to other tyre/rim concepts when appropriate rim/section ratios and coefficients are defined.
Key topics and technical requirements
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Tyre designation and marking
- Sidewall markings must show size and construction and service description (load index and speed symbol).
- Construction codes: B (bias‑belted), - (diagonal), R (radial). High‑speed categories use VB/ZB/VR/ZR and special marking conventions.
- Mandatory markings for tubeless tyres (“TUBELESS”) and rotation direction arrows where applicable.
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Calculation of design dimensions
- Procedures to compute the theoretical rim width, design section width, section height, and overall tyre diameter.
- Rim/section ratio K values given for aspect ratios (examples: K = 0.6 for 100/90/80; 0.7 for 70/65/60; 0.9 for 45–30).
- Rules for choosing the measuring rim width and rounding conventions.
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Maximum and minimum service dimensions
- Maximum overall width and diameter in service are calculated using coefficients (a, b) that depend on tread configuration (Types A–D) and tyre construction.
- Minimum section width requirements and tolerance rules (minimum difference and measurement procedure).
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Load‑carrying capacity and speed
- Tyre load‑carrying capacity (TLCC) linked to load index; applicable up to 210 km/h, with defined percentage reductions for higher speed categories (V, W, VB/VR, ZR/ZB).
- Guidance on centrifugal radius and factors to account for service growth and deformation.
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Measurement procedure
- Mount on measuring rim, inflate to recommended pressure, condition 24 hours at room temperature, then measure.
Applications
- Use this standard when designing or specifying:
- Motorcycle tyre geometry and tyre-to-rim compatibility
- Vehicle clearance and wheel arch design (vehicle manufacturers)
- Tyre labelling, marking and product compliance (tyre manufacturers)
- Regulatory documentation, test houses and OEM procurement
Who uses it
- Tyre designers and manufacturers, rim designers, motorcycle OEMs, homologation authorities, testing laboratories and component engineers.
Related standards
- ISO 5751 (Parts 2 and 3) - dimensions/load capacities and approved rim contours
- ISO 4249 (code‑designated series)
- ISO 4223-1 (tyre industry terminology)
- ISO 6054 (rim codes for small diameters)
Keywords: ISO 5751-1:2010, motorcycle tyres, metric series, tyre designation, tyre dimensions, load‑carrying capacity, speed symbols, rim/section ratio.
