As long as we're going over best practices: another thing to do is invest in a cheap dial gauge (e.g.
Amazon.com: Woodstock D3207 Magnetic Base with Dial Indicator in Case: Home Improvement ). When you first mount the rotor, put a couple lugnuts on medium-tight and spin the rotor on the hub against the dial gauge and check the total runout (min<->max reading difference). Then basically re-mount it in the other 4 positions (one lug-hole off each other) and measure again, and choose the mounting position with the least runout. What you're doing, basically, is making sure the small mfg variances in both the hub and the rotor are cancelling out rather than adding up (kinda like what they do with wheels and tires at a good tire mounting place).