I've seen some different wheel set ups, and not sure how to set up my skates. 2 grippier wheels on the front(1) and back(4). or the grippy wheels in the back two wheels (3)(4). or then obvious, the same wheel on all four. I've got a hi-lo 72-80, and I've been thinking about doing front / back what is everyones prefrence? Is there even a science to it?