Zimmerman Discs with Porterfields Pads = Squealing?

[clubhead]

I switched to new Porterfield R4S pads when the stock ones worn out. Had stock discs on then. Everything was well.

I then replaced my discs with Zimmerman's when the stock wear limit was reached. The pads started squealing The strange thing is they squeal when they get warm. The 1st few stops are fine but once it gets up nice and warm, it's starts.

Does anyone has similar experiences with Zimmerman Rotors and Porterfield R4S pads? My rears are fine as the stock rotors are still well within the wear limit.

I'm thinking of getting new stock rotors and really hope that'll solve the problem.