[Mike C]

Zero offset works best. That is where the mounting flange for the wheel is in the very center of the rim. 15" wheels can be a challenge. I have 17x8 on the front of mine with 4.5" back spacing (wheel width is measured between the tire sealing surfaces or "between the beads" so a 17x8 inch rim is 9" wide outside to outside, so 4.5" in from the back is exactly 1/2 way to the front, so it is not offset at all). I have 235 55 17 tires mounted. In the rear I run a 17x9 once again zero offset, so 5" back space with 275 55 17 tires. My '69 has a '71 5 lug axle swapped in and my truck is a stepside on leaf springs. All of those things have to be in alignment for that tire to work on a stepper. You have much more space in the rear on a fleetside truck as well as if you have coils.