Factory backspace for 14x5.5 rally?

I feel like I shouldn't need to start a new thread on this, but both my FABO and general internet searches are giving me conflicting information.

I have 14" x 5.5" large bolt pattern factory Rally wheels on my car (in sig pic). Are they all the same backspace, and if so, what is it?

The reason I ask is that I'm interested in buying a set of 14"x7" rallys with 4.25 backspace (wheel vintiques). I already have new 225/70's on the rear of my Duster, and intend to keep them. The reason for the wider wheel, aside from the fact that it would be a better fit for that tire, is that I'm trying to close the gap between the wide Duster rear wells, and my relatively skinny tires. I had thought of getting bold on spacers, but for the price of these wheels, it seems like a better choice. I'm simply trying to get a solid idea of how much further out I'll be with the 7" wide rims. Your thoughts on this idea are welcome, as well.