I will argue this all day, 0"
Why? Because when you do this, people always say 1"
You measure from the center of the fenders down.
you want it to be the same height all around.
Before anyone says something other,
look at where your front fender sits against the trim vs. the rear. The front sits on the same line as the top of the trim, and the rear sits on the bottom. Therefore if you bring them to an even height, you have already achieved the 1" rake.