ISO 6726:1988

Overview

ISO 6726:1988 - "Mopeds and motorcycles with two wheels - Masses - Vocabulary" is an ISO vocabulary standard that defines the terminology used to describe the masses and loads of two‑wheeled mopeds and motorcycles (as defined in ISO 3833). This second edition (1988) replaces the 1980 edition. The standard is strictly a vocabulary: it does not specify measurement methods, units, accuracy or numerical magnitudes.

Key topics

The standard clarifies and standardizes terms so that manufacturers, regulators and technical professionals use consistent language when discussing vehicle mass and load. Major terms defined include:

• Vehicle dry mass (vehicle set mass): mass of the vehicle ready for normal operation with required electrical equipment, legally required instruments and appropriate fluid complements (battery acid, coolant, engine oil). Fuel is generally excluded except where fuel/oil pre‑mixing applies (clarified in the text).
• Vehicle kerb mass: vehicle dry mass plus fuel filled to at least 90% of tank capacity and usual auxiliary equipment (tool kit, carriers, windscreen, protective equipment).
• Vehicle fully equipped mass: kerb mass plus optional or supplementary equipment supplied by the manufacturer.
• Manufacturer’s maximum total mass: mass calculated by the manufacturer for specific operating conditions, considering material strength, tyre loading capacity, etc.
• Maximum authorized total mass: mass established by administrative authorities for legal operation.
• Manufacturer’s maximum payload and maximum authorized payload: payload values derived from the difference between relevant total mass and kerb mass (expressed conceptually via gravity × mass difference).
• Distributed load, load ratio, and manufacturer’s maximum axle (wheel) load: terms for assigning loads to wheels and comparing distributed mass to total vehicle mass.

General conditions in the standard: supporting surfaces are horizontal, measurements are considered with vehicle stationary and engine off, wheels straight ahead, and definitions apply to factory‑new, normally equipped vehicles.

Applications

ISO 6726:1988 is practical for:

• Vehicle manufacturers and designers to write consistent specifications and technical data sheets (kerb mass, payload).
• Regulatory bodies and type‑approval authorities for harmonized definitions used in legislation and certification.
• Testing laboratories and conformity assessment to interpret mass‑related requirements without ambiguity (note: the standard does not prescribe test methods).
• Fleet managers, insurers and procurement specialists comparing vehicle capacities and limits.
• Technical writers, translators and standards committees for consistent terminology in manuals and regulations.

Related standards

• ISO 3833:1977 - Road vehicles: Types - Terms and definitions (normative reference for vehicle classifications used in ISO 6726).
• ISO 6725 series and ISO 9131 / ISO 9132 (related vocabulary and mass/dimension standards for two‑ and three‑wheeled vehicles) - listed in the bibliography.

Keywords: ISO 6726:1988, mopeds and motorcycles, masses vocabulary, vehicle dry mass, kerb mass, kerb weight, payload, axle load, ISO 3833.