Using my Al Krietler rollers this winter, I just put a new Michelin Krylion Carbon tire on my rear wheel and am now getting what appears to be black lumps on the free roller. It appears to be rubber tire debris and most scrapes off leaving only a stain until it builds up again after 20 miles.
This is new so I wonder if the tire is unusually soft and tearing away? It really is noticeable and only on the rear "free" roller. I use 115 psi, as I did with a Conti Grand Prix (got about 4000 miles before threads appeared).