E92 20mm Spacers?

Hi All,



I know there is already a lot of threads out their with some useful information but can get a bit confusing due mixed opinions.



I am looking to improve the rear stance of my E92 335D without any contact between the arches and wheels (even under full load). I currently have 19x9" ET39 Twist Alloys on the rear with Goodyear Assymetric 2's.



I know a lot of the guys would recommend I go with 15mm as the safest option but has anyone fitted 20mm spacers to the rears with the same setup/rim size without any issues?



Any feedback would be much appreciated



Thanks



Aff