It appears the 01-03 530i (525i?) ran a 17x8" 20mm offset front and a 17x9" 26mm offset rear in the style 42. perhaps the fronts could be bored to 14mm lugs and the rears run on ~50mm adapters? But it could be that the small early wheel well won't take a 8" rim & tire combo very well. I need to go search the forums, I'm sure someone has done this swap.
The info below is from my 'garage' - a previous owner gave me the details of my Fikse 17" wheels on my 87 Giugiaro Esprit.
Short answer: Yes - a 17x8" with 20mm offset should fit on front.
My rear is 17x9 but with a -25.5 mm offset due to its custom nature.
Definitely BBS Style 42 rear wheel with ET 26 will require a 50 (56) mm adapter if you want the OEM offset maintained.
My Fikse front wheel is 17x8.5" with 20 mm offset. Note that I am running only a 205/45-17 tire (not 215/15-17 as originally on my car). No rubbing.
4/29/2017 - reference for the Fikse wheels from a previous owner:
*Size = 15x7 with 195/60-15
*OEM Offset = Positive +23.3
*Size = 15x8 with 235/60-15
*OEM Offset = Negative -20.0
*Size = 17x8Ĺ" with 215/45-17
*Offset = Positive +20.3
*Size = 17x9" with 255/45-17
*Offset = Negative -25.5
1987 Esprit Measurements:
*FRONT Spigot 71.0 mm diameter 11.5 mm thick
*REAR Spigot 71.0 mm diameter 10.0 mm thick
*Bolt Pattern 5x120 - front and rear
*Center Bore 71 mm - front and rear
*Heat Shield 135 mm from mount plate to heat shield*