Actually going with the BF Goodrich Mud Terrain KM2's in a 255/85r16
they are 33" tall, will be 10" wide. I will have to run a 2" spacer in the rear, but I think it will work out well. With this combination it will pull 1963 RPM @65 mph. 2114 @ 70mph.
I am also going to run the centramatics with them to keep everything balanced.
I have seriously thought about running the 19.5's if I did though id swap out to the Dana 80, build 10 lug hubs for the front, and get an Atlas T case because they have provisions for the driveshaft mounted parking brake.