Tire options limited------------

So, I looked up the definition of backspacing and know that it is the distance from the inside of the wheel to the face of the mounting surface. Then I checked the backspace on my wheels and discovered that it is 4.25", these are 6" wide. So an 8" wide wheel with 4 1/2" backspacing will move my wheel 1/4" closer to the leaf springs and 1.75" outboard, closer to the wheel well. Armed with this information, I think I am ready to buy two of the wider wheels for the back and put on the biggest tires that don't rub the springs or wheel well. I am just not sure what size tire that will be but there is always air shocks:-)