bmw rims are 5x120mm bolt circle, GM is 5x4-3/4 or 5x120.65mm the back spacing on BMW rism is measured in ET, which is the distance in mm from the centerline.. so an 8 inch rim with ET12 has 4.5 inches of BS..
they go on just fine, if you are super woried about the .325 mm offset of the holes.. dont be... but if one were really anal, one could use flat faced lugnuts with conical washers...
heres mine with BMW "schnitzer" rims
do a search on ebay for staggered bmw rims and a million cheap and super cool rims appear.. again do the math, a 9.5 inch rim with ET25 is 5.5 inch BS, and which its my understanding fits on a 1.gen