When you are measuring for the adapter plates, what are you measuring to? I would assume that you are trying to get the center lines of the two different size tires to line up. Is that correct, or do you try and get the inboard of the wheel to go in the same ammount? I am trying to mount a set of 16x8 T/A wheels onto my Olds. The current wheels on my olds are 14x7 with a 3.5" Back Spacing, but what I have found online says that it should be 4.5", so these are not original wheels. I believe that the TA wheels have a 6.5" BS. Anyone done this before that can help me?

 

You want it to go in the same amount, so in your example you'd want a 2" adapter.

 

This was just posted a couple days ago... check out the current post for ur answers