Radial runout is variation in radius; lateral runout is side-to-side deviation as the assembly rotates.
Runout is geometry, not mass.
Measure wheel and tire separately when diagnosing.
Mounting error can imitate runout.
Excessive runout remains after perfect balance.
Radial runout
Radial runout appears as out-of-round motion and can create vertical vibration. Tire variation, bead seating, wheel deformation and eccentric mounting are common sources.
Lateral runout
Lateral runout appears as side-to-side wobble. Bent flanges, distorted wheels and mounting contamination are possible causes.
Finding the source
Confirm mounting repeatability, then measure the assembly and wheel reference surfaces. Mark high points and decide whether indexing or replacement is appropriate.
Diagnostic reference
| Finding | Possible meaning | Next check |
|---|---|---|
| Vertical hop | Radial runout | Measure tread and rim |
| Side wobble | Lateral runout | Measure wheel surface |
| Runout changes after remount | Centering error | Improve mounting |
Workshop procedure
- Verify mounting.
- Measure assembly radial and lateral runout.
- Measure wheel reference surface.
- Mark high points.
- Index or replace as needed.
- Rebalance.
Frequently asked questions
Can balance weight reduce runout?
No. Weight changes mass, not shape.
Can poor bead seating cause radial runout?
Yes.
Does lateral runout always mean a bent wheel?
No. Mounting error can also cause it.
Technical review edition · Published 17 July 2026.