I'd be very very surprised if they fitted onto a standard arched and lowered RST.205mm is the widest normally seen on one,that extra 30mm would cause rubbing I'd say.As for the 610 diameter,my slicks which are 570 just about fit into the rear arch without rub,and my RST is only -25mm lowered.Pity,as Tony your selling at a good price.Regards,Micky