Backspacing on ZR2 wheels

[chevy2tuff2006]

Does anyone know the backspacing on the stock Zr2 18" wheels? I have a bds 3" lift on my 20 hd and having to run 1/2" spacers on the front to make the stock 18" work.  Just wondering if I could run these with out spacers.

[newdude]

GM doesn't have a spec published anywhere yet that I can find.  I'm gonna take a wild a$$ guess and say its +44mm like the standard wheels or somewhere about +40-44mm.  They are the same 18x8 as the stock 18s so +44mm isn't out of the question.  

[MTU Alum]

12 mm delta from stock

[Epsilon Plus]

Are you sure they are 18x8? They are running 12" wide tires on them (305/70). Discount Tire wouldn't mount anything over an 11.5" on a 8" wheel for liability so I'm sure GM wouldn't either. Probably more like an 18x9 or 18x8.5.