Problems replacing 1976 Dodge "16.5 rims to common size

You will have a blowout on dual rear tires if the two facing sidewalls are too close together. The "dish" of the wheel determines that spacing. The wider the tire the more offset(spacing) you need to keep the sidewalls apart. The offset distance is built into the wheel. The offset requirement is determined by the tire. It used to be easy to find a graphic showing that. Not so much lately. I'll see what I can find.