Z4 Wheel Spacers Size

[CNLimit]

Hello to all,
I am looking into putting some spacers on my 2007 Z4 Coupe 3.0si (With Sport Package). I will be using the Sport package's factory wheels 18 x 8.0 front/18 x 8.5 rear Star Spoke (Styling 203) light-alloy wheels and 225/40R-18 front/255/35R-18 rear run-flat performance tires. Has anyone done this or knows how wide can I go without scraping the wheels and wheel wells? Thanks in advance for your ideas and advice!
ED

 

[Color]

CNLimit, don't know about the spacers, but I just wanted to say that is one cool photo!
Did you consider entering it into the photo competition??

 

[CNLimit]

I would like to, but I have not seen the December post to load some up. Thanks for the compliment!