Guy,s with a B Body rear end...Questions

First thing I would do is get the rear end in, then measure from the face of the drum back to the spring and minus an inch to set your backspacing! Then I would measure from the face of the drum to the wheel lip and minus an inch there also! Add the backspace number to the front offset and that will give you your rim width! Then you need to convert the tire width from millimeters to standard measurement to figure your maximum tire width for your rim size! Any tire shop can tell you what the maximum tire width for any particular rim is, but figuring that 215mm is the max on a 5.5" rim, you can divide 215 by 5.5" and get the mm per inch of tire width, which would be 39mm per inch of rim width! Assuming you can run an 8" wide rim, you can safely run a 295mm wide tire!