Spacers question... for stock 18" CLS 500.



I have a 2006 CLS 500 with stock OEM 18'' wheels... because of the sorry roads around my town, I don't wanna go higher than 18", so I bought a "Renntech ELM" from member "Emoving" and will be lowering my ride to the max, that said, WITHOUT the lowering my wheels look a tucked in, so, I can imagine that when I do lower, my wheels will look HEAVILY tucked in.
I was wondering someone would recommend 20mm spacers for the rears and a 12-15mm for the front wheels?, would they stick out too much??, I would like my wheels to look more aggressive than just flush, does that make sense?
Many thanks for the help!

These are my wheels, I really like them, I plan in painting them glossy black with black or CF center caps.



