A customer just sent us some photos of his Jet Black e90 non-M with Race Silver EC-7s wrapped in Hankook R-S3s, which would give you an even better idea.
This customer is using the 18x9.0" ET31 front with a 245/40/18 R-S3, and the 18x10" ET43 rear with a 285/35/18 R-S3 and 5mm spacer, with a rolled rear fender.
If you are looking for the widest wheel combination that is most flush for your e92 335i, we would recommend the 18x9.0" ET31 fronts and 18x10" ET33 rears. You can run the 245/40/18 and 275/35/18 street tires, and you should not need a fender roll like you would have with the 285/35/18 that is pictured above. This would also sit more flush to the fender than the shown setup by 5mm as well. This would be the most wide functional setup that you can put on your e92 335i to get some nice rear traction with a 10" wide wheel.