ISO 5751-3:2010

Overview

ISO 5751-3:2010, "Motorcycle tyres and rims (metric series) - Part 3: Range of approved rim contours", specifies the approved rim contours and profile codes for motorcycle rims designed to accept metric-series tyres. The standard defines the allowable rim profiles, provides tabulated rim codes and nominal tyre bead sizes, and gives the coefficients and calculation rules used to determine minimum and maximum rim widths for safe tyre fitment.

Key topics and technical requirements

• Approved rim contours and profile codes: Tabulated rim profile codes (e.g., MT7.00, MT8.50) mapped to nominal tyre bead sizes (S) for different tyre series.
• Width calculation rules: Minimum and maximum rim widths are calculated using the tyre’s nominal bead size (S) multiplied by coefficient values Nmin and Nmax from the standard (Minimum rim width = S × Nmin; Maximum rim width = S × Nmax).
• Coefficient tables: Coefficients vary by tyre series and construction (diagonal, radial, bias-belted), and are provided in Table 1 for accurate rim-width determination.
• Compatibility notes: Guidance on when specific rim profiles are suitable only for certain tyre structures (for example, entries in parentheses indicate applicability only to diagonal or bias-belted tyres) and cautions about mounting motorcycle tyres on rims intended for other vehicle types.
• Cross-references: Rim dimensions, marking and detailed profile dimensions are referenced to ISO 4249-3 (codes 13 and above) and ISO 6054-2 (codes 12 and below). The standard works together with ISO 5751-2 (tyre sizes and load capacities).

Practical applications and users

Who uses ISO 5751-3:2010

• Tyre manufacturers and rim designers specifying approved rim contours for product lines.
• Motorcycle OEMs and suppliers verifying component compatibility and safety margins.
• Aftermarket rim and tyre suppliers ensuring correct tyre-to-rim matching.
• Vehicle homologation, testing laboratories and regulatory authorities assessing conformity.
• Service technicians and tyre fitters referencing approved rim profiles for safe mounting.

Benefits and real-world value

• Ensures correct tyre-to-rim fitment to reduce risk of tyre failure and improve handling.
• Standardizes rim profile identification across the supply chain for metric-series motorcycle tyres.
• Facilitates regulatory compliance and homologation by providing clear, accepted contours and calculation methods.

Related standards

• ISO 5751-2 - Pneumatic sizes and load capacities (metric series)
• ISO 4249-3 - Rims for coded-dimension series (codes ≥ 13)
• ISO 6054-2 - Rims for coded-dimension series (codes ≤ 12)

Keywords: ISO 5751-3:2010, motorcycle tyres and rims, rim contours, metric series, approved rim profiles, rim width calculation, tyre-to-rim compatibility.