Apparently Pirelli have a problem producing tyres that recover once overheated. I found this very interesting:
http://www.motorsportmagazine.com/op...roblem-another
"There is a theory out there that the chemical constituents needed to get the rubber liquid enough to be extrudeable (as in toothpaste from a tube) in Pirelli’s highly automated Istanbul plant are the very ingredients that cause the tyre to permanently harden when it becomes too hot. The chemical links that allow the polymers to be long (and the rubber therefore bendy) break down. If this is indeed the case, then the only way to prevent the phenomenon whilst retaining this production process would be to make a tyre with a less stressed contact patch – either by increasing the size of the contact patch or making the compound tough enough that it never got close to the ‘frying’ threshold. Or both. But that would then risk making for a tyre with performance that didn’t degrade at all…
That might be exactly what we now have."