Mate - Scott (aka @warp9.9 ) did a conversion to 18" ages ago. And the C/F wheels are 18". But I feel that a 200/55ZR17 on the rear would be outstanding. I have a rim but the only place I know that does them with an EC certificate of Homologation is DEGET in Germany. Not WICKED expensive - but with my Guzzi in bits and having a new car to pay for - well a 17" rim is not URGENT.