Dealer seems to be cheating a little. 20x9 ET20 is too agressive. Somebody has them refused.
All Vertini RF1.1 are being sold initially with the front ET35 rear ET45 as you said at the beginning, just watch:
http://www.ebay.com/itm/20-Vertini-R...-/201353284045
http://www.bonanza.com/listings/20-V...-550/257848744
The optimal wheel specs for F10 are: F 20x9 ET25 and R 20x10.5 ET35. That's why we were talking about the 10mm spacers option for the initial specs. Ask the dealer "Is there still a room for changing offsets?" and let's see what he says then.