I spaced my fenders evenly all the way around my tire, centered it front to back, then raised it about that much on top. In my case, with the present tire/wheel combination, there's about a 3.5" clearance. I leveled the frame to the ground (ya, I know, my driveway slopes down hill) or at least parallel with the driveway, then used my jack stants raised up evenly (same number of clicks) until I got my desired height.

Your tire won't come up much past your maximum axle to frame clearance (hopefully you won't hit that large of bump). But when my axle was mounted under my springs I sure wasn't going to put my fender 6" above my tires!

Sometimes you just have to stand back and say "that don't look bad" or "well, I thought it was ok, but that really looks stupid".
Just my thoughts, didn't say they were good ones.
