Newbie question
 

But I have to ask.

How do some guys drop the front end of their car so the top of the wheel well is flush with the top of the wheel and still maintain any sort of turning radius?

My next project is going to have coil overs and I would like to get the car as low as possible, but still driveable? I'm sure this will effect the backspacing on the wheels I choose also.

You basically summed it up right in your post under the question. Proper width, diameter and backspacing is they key to nailing fitment and stance.

They also roll the lips on the fenders. This allows more clearance for the tire when damping and turning as well.