reginos:
fritz:
RC:
fritz:

It's harmless. It's just a replaceable insert in the mould. For instance, to allow changes to be added later, like additional lettering or numbers. It's just like the oval date stamp insert next to it, which has to be changed every time a new batch of tyres is made to correct the production week number. 

Thank you. Smiley What is weird is that the other tires don't have it. Smiley

Then it might be be a rather poorly executed repair in the surface of just one particular mould, due to a mark or local damage to its surface.  Smiley
It won't have any influence on the integrity of the tyre. 

I think the worker must have dropped a coin in the mould Smiley

Reminds me of the story of a Ferrari F1 team worker dropping a mechanic's steel rule into a mould when a F1 carbon fibre tub was being laid up, and it got moulded into it. It was only discovered when the very expensive monocoque was finished, after having been baked in the autoclave, and it had to be scrapped due to the risk of the foreign body weakening the tub.  

Maybe he went to Pirelli after being fired by Ferrari?  Smiley


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fritz