This Write-Up was originally created by SHORTBUS on the other JK forum
Rewritten & pics
Want an easy 1" for tire clearance but hate the 1" gap...... Here's an easy way to remove the gap:
13/32 Drill Bit
10mm-1.5 nuts (2)
Lock Washers (2)
Remove the rear bumper and all 4 brackets attached to it.
Install the side brackets back onto the frame, but this time shift the bracket up so the lower hole in the bracket lines up with the upper hole in the frame and bolt it in place.
Using the upper hole in the bracket as a guide, drill a new hole through the frame.
Fab up 1" longer brackets for the centre of the bumper.
Remove the side brackets from the frame and reinstall all for brackets back onto the bumper in their stock locations.
Install the bumper in it's new location.
I installed a 1.25" RC Body Lift, so there's still a 1/4" gap. If also done a MBRP Muffler Relocation Kit, so the muffler wasn't in the way either
See below pics for a visual reference & additional info:
Rear Bumper Side Bracket (Remove both bolts)
Rear Bumper From Behind
Side Bracket In New Position
Rear Bumper Center Bracket
Rear Bumper Removed
Before Gap Elimination
After Gap Elimination