Displacement map scale or alignment

[enyo]

I found a decent spanish tile roof map that had no displacement with it. I desaturated it, put a slight gauss Ian blur on it and tweaked the levels to get more contrast. Hopefully it will work, but the problem I'm having is that it doesn't align with the diffuse map.

I usually import image as texture and map/ scale it on the object and if the other maps are the same pixel dimensions specular, bump maps et work.

Any ideas on what I'm doing wrong? Using VRAY 2.0 and am also experimenting with linear workflow.