I would go back to the original 9" and 10" BBS barrels that came with the wheels and run 255/30, 285/30. This is the very reason that I recommended you not switch the barrels when you posed the question in your original thread. Unfortunately you are very limited with tire sizing on 20" wheels...
Nitto Invo's and Hankook V12's are both downgrades from OEM tires. That's another issue with 20" wheels, not only are you limited in sizing, but also the quality of tires available in that sizing. In other words I would consider Nitto NT05's and Hankook RS3's but both of those are not available in 20". I admit that I'm anal when it comes to wheels / tires. I think that they need to be an upgrade if you are going to change them from stock.... Otherwise why do it?
'13 SSII M3 Coupe - KW Clubsport 3-way (Eibach Front Spring Conversion), Akrapovic Evolution, ESS Tune, StopTech Trophy, IND Euro Front Bumper and Gloss Black Mirror Covers, TMS Studs/Lugs, BMW Performance Carbon Fiber Spoiler/Interior Trim/Center Console, BMW Edition Grills/Gills, BMWPedals Extended DCT Paddles, Mode Carbon GT4 Splitter, Advan TC3 (18x9.5/10.5), BBS E05 (18x10/11), G-Force Rivals (275/35/18, 295/35/18)