1994 astro,4" BD, wheel help!

i'm looking into these types of wheels,But i'm not having great luck understanding this offset stuff. i see the size and width are good. Also the back spacing,but the offset,not sure
 
 
http://store.summitracing.com/partdetail.asp?autofilter=1&part=USW%2D52%2D5715&N=700+4294923105+4294795102+4294755959+4294793325+115&autoview=sku
 
going for a old skool look

ok a 15 x 7 rim is actually 16 x 8 if u lay a tape measure on it. they dont count the bead/lip of the rim when they list the size. the backspacing is exactly what they say if u put a straight edge on the backside or the rim and measure inward. this is where the face of the disc or drum meets the back of the rim. so a 15 x7 rim with a 4 in backspace is evenly centered. now its up to u to know how far out your wheels can go without rubbing the inner fenderwall. also how far back from the face of the disc or drum it can go without rubbing suspesion/fenderwell,etc. hope this helps. this rim might not be available in custom offsetsm your high dollar billets come custom built but take up to 2 months to get.

DAMNNNNNNNNNNNNNNNNNNNNNNNNNNN   Sick van!! Marcus........... Thanx for the little info.