I never saw a police P6 with Minilites, only "S" wheeltrims, and I worked on a lot of them. As for the Minilites fitted to police Sd1s I have a set of those fitted to my P6B and have never noticed any problems with it.
Do the SD1 minilites have a larger centre hole than the p6 ones? I have a set with the larger hole but wondered what they were off. What centre cap did you use?