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Useful notes related to tyres and wheels > < Rise of temperature in tyres with insufficient air pressure

Polo Mk4

Damages to the tyres due to assembly failure (assembly damages)
Damages to the tyres due to assembly failure (assembly damages)
Bead core broken while inflating the tyre
   
The updated radial tyre for passenger vehicles are exclusively assembled in safety wheels. These wheels have an elevation around the shoulders -1-.
1 - protrusion (double protrusion H 2)
2 - flap of the wheel
3 - inner shoulder of the wheel (for example, inclined shoulder)
4 - wheel
5 - central disc of the wheel
6 - base
7 - outer shoulder of the wheel (for example, inclined shoulder)
The protrusion avoids the compression of the tyre by wheel shoulder if the vehicle is driven with insufficient inflation pressure.
When inflating the tyre, it may happen that the tyre bead does not slide completely over the wheel's protrusion.
In this case, there is the danger of bead core dilatation, due to excessive inflation pressure, when the corresponding steel wires break totally or partially. The slots in the tyre bead core are not detectable from the outer portion.
  WARNING
t  The tyres with damaged bead core do not have a good seating on the wheel. These tyres represent a danger for the safety!
t  Moreover, there is the danger of a bead core partially damaged breaking completely, while the vehicle is being driven, and the tyre may suddenly open. If the bead core breaks while the tyre is being inflated, the case will also be destroyed.
  N44-10214
Tyre with damaged tyre bead core and destroyed case
The figure shows a tyre with the bead broken and the case destroyed due to excessive stress during the assembly.
Damages in the tyre bead caused by deficient or incorrect assembly with assembly machines
The following failures that happened during the assembly of the tyres may cause serious consequences to the tyres:
t  when inserting the upper bead of the wheel, at the tyre assembly machine, the tyre bead on the opposite side does not seat completely to the base → Anchor
t  when the assembly head was misadjusted
t  when the edge of the assembly roll slides on the bead roll.
t  when the guide rolls are worn and with pointed edges
  N44-10238
Tyre with damaged bead
In these cases, the bead subject to great stress may be cut in the axial direction, damaged and/or compressed up to the wire of the core.
Frequently, vestiges of seat and sliding of the guide roll at the machine are detected at the damaged area.
  Note
Both tyre beads and the wheel shoulders shall be always lubricated with Assembly paste -G 052 109 A2-. Refer to the → Chemicals Manual.
If imperceptible assembly damages remain, there is the danger of rendering the tyre useless later, during driving.
FOR THIS REASON!
t  Never assemble without Assembly paste -G 052 109 A2-.
t  Do not inflate the tyres with more than 3 bar, in order to make the thrust to the wheels.
t  Never inflate the tyres with more than 4 bar.
t  At the end of the assembly operations, reduce the air pressure to the specified value.
  N44-10239

Useful notes related to tyres and wheels > < Rise of temperature in tyres with insufficient air pressure