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Difficulty: MediumWheels and Tires

An automotive technician is inspecting a wheel and tire assembly for ride disturbance and vibration concerns. Match each balance or runout condition with its corresponding mechanical characteristic.

  • Static imbalanceA single heavy spot on the circumference causing vertical wheel bounce (tramp)
  • Dynamic imbalanceUnequal weight distribution on opposite sides of the centerline causing side-to-side wheel shimmy
  • Radial runoutOut-of-round geometric variation in assembly radius causing up-and-down hop
  • Lateral runoutAxial side-to-side wobble or deviation of the rim flange or tire tread

Answer

Static imbalance matches a single heavy spot causing vertical tramp; Dynamic imbalance matches dual-plane weight asymmetry causing lateral shimmy; Radial runout matches out-of-round geometric variation causing vertical hop; Lateral runout matches axial side-to-side wobble.
Each condition matches its specific mechanical and directional definition: static imbalance creates vertical tramp due to a single heavy spot; dynamic imbalance generates lateral shimmy due to two-plane mass offset; radial runout represents out-of-round geometric eccentricity; and lateral runout represents axial side-to-side wobble.

Step-by-Step Solution

1
Distinguish between mass imbalance and geometric runout conditions
Imbalances relate to mass distribution (static and dynamic), whereas runout relates to physical/dimensional deviation (radial and lateral).
Correct automotive diagnosis requires isolating weight defects from dimensional defects.
2
Correlate single-plane and dual-plane mass distribution with their directional vibration modes
Static imbalance creates single-plane vertical hop (tramp), while dynamic imbalance creates two-plane rotational rocking (shimmy).
Static imbalance acts purely radial-centrifugal, while dynamic imbalance produces a rocking torque across the wheel centerline.
3
Correlate radial and lateral runout with their geometric axes of deviation
Radial runout is variation in radius/roundness, while lateral runout is axial side-to-side rim/tire wobble.
Dial indicators placed perpendicular to the tread measure radial runout, whereas indicators placed parallel to the axle against the sidewall or rim lip measure lateral runout.

Key Concept

Wheel and Tire Balance and Runout Diagnostics
Estimated Time:1m 15s
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Topics

Wheels and Tires

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