Inspection | Automobile Tire Inspection Standards and Methods

1. Appearance quality inspection

1. Prohibited defects (directly judged as unqualified):

   • Delamination of components, sponginess (bubbles)

   • The wire ring is broken and seriously pulled up

   • Multiple cords are broken and the tire cords are wrinkled

   • Crown rubber sideband cord

   • Missing or cracked cushioning strips (if applicable)

2. Minor defects (according to enterprise standard limits):

   • Sidewall glue missing, impurity marks, uneven joints

   • Bead deformation, unclear markings, etc.

2. Tread wear signs and markings

1. Wear signs :

   • Circumferentially evenly distributed ≥ 4, height ≥ 1.6mm (passenger car tire)

2. Indicator Marking :

   • The "△" or "TWI" symbol is engraved on both shoulders to indicate the wear mark position

3. Data Measurement

(Need to refer to GB/T 2978 and other standards)

4. Safety performance inspection (sampling laboratory test)

1. Strength performance test

• Applicable to : bias tires, radial tires (height-to-width ratio ≥ 50), T-type spare tires

• Standard : Destruction energy ≥ specified value (e.g. passenger car tire ≥ minimum energy value, GB standard Table 1)

2. Tubeless tire bead unseating resistance

• Applicable : Tubeless structure (same as above)

• Standard : Bead unseating resistance ≥ specified value (e.g. passenger car tire ≥ minimum resistance value)

3. Durability test

• Result judgment :

  • Air pressure drop ≤5%

  • No delamination, cord breakage, chipping, cracking, or carcass deformation

4. Low pressure performance test (radial tires only)

• Same as durability test criteria

5. High-speed performance test

• Result judgment :

  • Air pressure drop ≤5%

  • No structural damage (300km/h+ tire tread blistering is allowed)

6. Rolling resistance performance (radial tires only)

• Restriction : Rolling resistance coefficient ≤ standard maximum limit (EU label A level is the best)

7. Wet road grip performance (radial tires only)

• Restriction : Wet grip index ≥ standard minimum value (e.g. EU label B grade ≥ 1.1)

5. Special considerations for export inspection

1. Regulatory Compliance :

   • EU: ECE R30/R117 (noise, rolling resistance, wet grip label)

   • United States: DOT certification (FMVSS 139)

   • Middle East: GCC certification

2. Document Verification :

   • Test report (including factory number), certificate of origin, MSDS (sea shipping)

3. Packaging and marking :

   • The packaging is intact and the shipping mark is clear (specification/model/production week number/DOT number)

6. Final inspection process before shipment

1. Batch sampling : sampling according to AQL 2.5 or customer requirements (e.g. 80 pieces out of 1000 pieces)

2. Quick four-step method :

   • Look at the appearance : 360° inspection of structural defects under lighting

   • Dimension measurement : Use a caliper to measure the section width/outer diameter (compare with the tolerance table)

   • Nuclear identification : DOT number, production date (e.g. 3523 = 35th week of 2023), specification/speed symbol

   • Packaging inspection : barcode can be scanned, box label is consistent with the actual product

3. Preserve evidence : take photos to record defective tires + test report

Key national standard references

• Appearance and dimensions : GB/T 521

• Passenger car tire standard : GB/T 2978

• Safety test methods : GB/T 4502 (strength), GB/T 4503 (bead unseating)

• Performance test : GB/T 7035 (durability), GB/T 4504 (high speed)