Rohanna makes their wheels in specific offsets and sizes. Some will fit perfect and some have to be made to fit with spacers/grinding etc... Are you using the RC7? Think that is one of the few wheels they have in our bolt pattern with a +42 for the front and a +45 for the rear.
The factory front wheels are not hub-centric and are lug-centric.
they are the RF1 series. I don't know about all the other technical stuff.