wheel size

[m3iceman]

I am trying to find out what the appropriate rim size I wheel need to go up to a 17" rim on my 92 525i. I want to go wider in the back, does the offset become different than the standard 20mm. Do I use a 17x7 or 17x8 or 17x9, and what tire size works good? Thanks.

[mike wong]

the M5 uses 17x8 ET20mm, 235/45x17 tires.
the staggered set uses a 17x9 rear wheel, 255/40x17 tire - unsure of the offset, think it is 22 or 23 mm.

[Paul in NZ]

In the real world having different size tyres is a pain....what do you do for a spare...it makes rotation impossible to even out the wear,and you cant rotate when you lose a tire to road hazards to try to keep similarly worn tyres on the same axle
I am a fan of 5 tires and wheels exactly the same.....my 2c
I have four 17x8 with 235/45x17s and one strange metric size on a style 5 type wheel......