As far as the factory wheels go, yes, all 2nd gen rims were 15x7 with a 5 on 4.75" bolt pattern except for the rare ZQ8 rims that were 16x8 w/ 4-1/4" BS.

4wd rims have 6" back spacing and after taking into account the stock wheel lip width, the offset would end up ~51mm.

2wd rims have ~4" back spacing which results in a near 0 offset.

http://i11.photobucket.com/albums/a1..._technical.gif

http://www.tirereview.com/when-is-it-overkill/

I found this article quite informative.