ISO 5751-2:2010

Overview

ISO 5751-2:2010 - "Motorcycle tyres and rims (metric series) - Part 2: Tyre dimensions and load-carrying capacities" - is an international standard that specifies tyre size designation, dimensional data and standardized load-carrying capacities for metric-series motorcycle tyres. It applies to tyres with a height-to-width ratio of 100% and below and provides the technical basis vehicle and tyre manufacturers, testing laboratories and regulators use to ensure compatibility and safe operation.

Key topics and technical requirements

• Tyre designation and marking
  • Specifies the tyre size format including service description (load index and speed symbol). Example marking formats: 100/90 – 18 M/C 56 P (diagonal), 100/90 R 18M/C 56 P (radial).
• Tyre dimensions
  • Tabulated design and in‑service dimensions (section width, overall diameter) for multiple size series. Tables 1–14 list design and maximum in‑service widths/diameters for different tread configurations.
• Measuring procedure
  • Defines mounting and inflation procedures for measurement (measuring rims per ISO 5751-3), required inflation pressures for normal/extra/light-load tyres, and a 24 h conditioning period prior to taking measurements. Example inflation guidelines include 225 kPa, 280 kPa, 330 kPa depending on load and speed symbol.
• Tread configurations
  • Classification of tread types (A–D) with common service attributions (highway, off‑road, mixed).
• Load ratings and load indices
  • Tables 15–29 provide standardized maximum load‑carrying capacities per tyre size; Annex A contains harmonized load indices. Provisions allow adjustment of load capacities at reduced speeds (see Table 30).
• Inflation pressure guidance
  • Recommended inflation pressures tied to rim diameter codes, tyre versions (light/normal/extra‑load) and speed symbols. These are guideline values to be agreed between tyre and vehicle manufacturers.

Applications and who uses it

• Tyre manufacturers - design, mark and certify metric-series motorcycle tyres for consistent dimensions, load ratings and compatibility with approved rims.
• Motorcycle and vehicle manufacturers - select tyres and specify clearances, load capacities and inflation recommendations during vehicle design.
• Test laboratories and certification bodies - verify tyre dimensions, perform load/pressure testing and confirm compliance with ISO requirements.
• Regulatory agencies and fleet operators - reference for safety, type-approval and maintenance guidance in procurement and inspection.
• Aftermarket retailers and mechanics - use dimensions, load indices and inflation guidance to recommend correct tyre fitment and pressures.

Related standards

• ISO 5751-1 - Motorcycle tyres and rims (metric series) - Part 1: Design guides
• ISO 5751-3 - Part 3: Range of approved rim contours (measuring rims)
• ISO 4223-1 - Definitions of tyre industry terms

ISO 5751-2:2010 is essential for ensuring safe, interoperable tyre and rim combinations in the metric motorcycle tyre sector and supports consistent specification of tyre dimensions, load‑carrying capacity and measurement practice.