I would say it's pätka poškodená ráfikom (not absolutely sure though). I've found a document including some definitions and pictures related to tyres. Maybe it'll help you
h t t p: // w w w (dot) europarl.europa.eu/meetdocs/2004_2009/documents/com/com_com(2004)0774_/com_com(2004)0774_sk.pdf