offset= the relation of the rim mounting surface compared to center line of rim width. Example: 15x7 CJ rim. 7 inches is inside bead to inside bead, rim is 8 inches overall with a centerline at 4 inches and backspacing of 3.5. Backspacing is distance from the inner edge of the rim to the mounting surface. So that's 1/2 inch negative offset. Negative because the mounting surface is on the inside section of the centerline.
1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon