widest wheel and tire combo for stepside?

[First66]

Originally Posted by 19GMC63

With stock ride height you could easily tuck 15x10s in with the proper offset, especially if your using a stock diff. The diff in the gmc is from a late model which is almost two inches wider then stock, and with 15x12s, tires stick out about 3 1/2 inches from the fender edge, too much for me.

You seem to be the best person to ask, 19GMC63

1. What offset would clear me to run 15x10's on the rear of a Step '66 at stock height.

2. If I were to lower it 3-4 inches all around, would the same setup work?

Thanks.