ET45 for 8.5 is OK, but you won't like it. Look at the OEM 20" BMW wheels, they are ET45. But not good looking. 8.5" can definitely go for ET35.
My rear setup will be ET35 for 9.5", front is ET35 8.5"
Originally Posted by oedipol
depends on the size of your rear wheel: ET 45 is good for 8.5"