Bead control keeps the tire section opposite the working area in the wheel drop center to create the clearance needed at the rim flange.
Most excessive force comes from losing the drop center.
The working point and hold-down point stay opposite.
Stiff tires need active helper-arm control.
Stop and reposition instead of forcing the machine.
Clearance geometry
The bead does not freely stretch over the outer flange diameter. The smaller drop-center diameter creates the needed path length.
Holding the bead down
Use the helper arm or approved depressor and move the support as the turntable rotates. Multiple points may be needed on stiff tires.
Warning signs
Stop if force rises sharply, the sidewall stretches excessively or the bead climbs out. Reverse slightly, relubricate and restore position.
Diagnostic reference
| Finding | Possible meaning | Next check |
|---|---|---|
| High force early | Bead not in drop center | Stop and reposition |
| Bead climbs out | Support not advanced | Move helper arm |
| Sidewall pinched | Wrong tool path | Release and inspect |
Workshop procedure
- Identify drop-center position.
- Lubricate bead and rim.
- Set working point.
- Hold opposite bead down.
- Rotate slowly while moving support.
- Stop at abnormal force.
Frequently asked questions
Why does the opposite side matter?
It creates slack at the mount head.
Can force replace bead control?
No. Excess force risks damage.
Why are low-profile tires harder?
Their stiff, short sidewalls climb out of the drop center easily.
Technical review edition · Published 17 July 2026.