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?
'08 E90 M3 - Alpine White - Sold
'13 E92 M3 - Silverstone II - Sold
'04 E46 M3 - Jet Black - BBS E88, KW Clubsports, Brembo BBK, SuperSprint Exhaust