ISO 13326:1998

Overview - ISO 13326:1998 (Tyre uniformity test methods)

ISO 13326:1998 specifies standardized test methods, equipment and controlled conditions for verifying tyre uniformity of passenger car, commercial vehicle and motorcycle tyres. The standard focuses on repeatable measurement procedures that detect non‑uniformity around the tyre circumference - a source of periodic forces transmitted to the vehicle during each revolution. It defines what to measure (geometry and force parameters), how to measure, and minimum apparatus capabilities, but it does not provide grading limits or quality levels and excludes methods for static/dynamic unbalance and tyre‑wheel assembly tests.

Key topics and technical requirements

• Measured parameters
  • Radial force variation (RFV)
  • Lateral force variation (LFV)
  • Ply steer and conicity (components of lateral force offset)
  • Radial and lateral geometric run‑out
  • (Tangential/tractive force variation is noted but not covered)
• Equipment essentials
  • Test drum types: Type A (preferred Ø 854 mm) and Type B (preferred Ø 1600 mm), with specified run‑out and residual unbalance limits
  • Test rim requirements (width, rigidity, run‑out and bead seat symmetry)
  • Measuring system with transducers for Y (lateral) and Z (radial) force components and optional phase/ harmonic analysis
• Performance and environmental constraints
  • Rotation speeds for measurement: 10–250 r/min
  • Force measurement ranges (e.g., ±1000 N Type A, ±3000 N Type B)
  • Ambient and calibration conditions (temperature control, IEC climatic category B2)
  • Structural resonance and vibration isolation requirements to limit measurement error
• Test preparation
  • Controlled tyre temperature (5 °C to 40 °C), correct mounting and inflation, drum surface friction, and warm‑up procedures for repeatability

Applications and who uses ISO 13326

• Tyre manufacturers - production verification, process control, root‑cause analysis of uniformity issues
• Automotive OEMs - supplier qualification, vehicle ride and NVH (noise, vibration, harshness) investigations
• Independent test laboratories - standardized tyre uniformity reports for customers and regulatory compliance testing
• R&D and validation teams - design optimization, harmonic analysis and phase mapping of non‑uniformity effects Practical uses include detecting periodic force sources that lead to vibration, steering pull, or uneven wear and supporting corrective actions in design or manufacture.

Related standards

ISO 13326 references and complements other tyre and metrology standards, including ISO 4000‑1/2, ISO 4209‑1/2, ISO 4249 series, ISO 5751, ISO 6054, ISO 4223‑1, ISO 8855, IEC 60654‑1 and the VIM vocabulary. These provide tyre dimensions, definitions and environmental/calibration norms used alongside ISO 13326.