TJ Flares for a CJ/YJ:
Adding TJ flares to your CJ/YJ can be a cheap way to gain extra tire clearance. TJ flares will give you the same amount of room as a set of cut-out flares. Since a new set of TJ flares is roughly $100, and used sets can be had for $60, this is a relatively cheap way to clear 31s on a stock YJ. There is cutting and drilling involved though. You will have to cut roughly 1" out of the tub everywhere.
For reference, here is an old picture of my YJ with stock YJ flares:
Here is the same setup, with TJ flares: