Tire Geometry

What about Tire Geometry?

Since beginning of the eighties the company Seichter GmbH examines the rubber tire surface regarding defects - thus deviations from ideal tire geometry. It began with the search for bulges and depressions on the side panel of the motor-car tire.

The convexities - bulges - can represent a substantial danger for security. In particular, if the cause is a fabric error in one of the internal tire layers. Here the side panel of the tire is weakened. Consequently the danger exists that the tire is destroyed while driving.

The indentions - depressions - are possibly caused by the fact that here the fabric layers of the tire overlap. That provides for a reinforcement of the side panel. Here the side panel does not expand so much, if the tire is filled. That looks optically simply bad. It is however not safety-relevant.

After demands of the automobile and the tire industry
bulges and depressions are not to cross certain limit values. Geometry measuring machines in the final inspection of the tire manufacturers provide for an automatic segregating of incorrect tires.

Which analyses of tire geometry are available?

The following characteristics of tire geometry are examined for the evaluation of the quality:

  • Bulges
  • Depressions
  • Lateral runout
  • Radial runout
  • Wobble
  • Tread radius
  • Tire circumference
  • Harmonic analysis at tire side wall and tread

Which measuring techniques are used?

The following measuring techniques are used for the analysis of tire geometry:

  • Mechanical sensors
  • Capacitive sensors
  • Laser sensors: Line lasers using the triangulation procedure
  • Sheet-Of-Light imaging sensors: Combination of laser and camera for the laminar scanning of the tire side wall


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