Lindseys are made from an original 16x6 wheel center and welded into a 17" barrel. They was never a 17" original Fuchs, so there is no way to go 18".
I purchased Lindseys because I really like the classic look and wanted to get wider than 245 rubber in the rear. I am replacing a set of Kinesis k18r with these Lindseys. I thought the Kinesis looked great, but sometimes they seems a little big and out of place to me. I have always thought that it is funny how when a car is newer, the new rims add something, but when they become classic after @ 20 years, the original rim looks best. I remember in the 80's when I thought that gold centered BBS when the coolest looking wheel on Porsche and BMW. Now I can't stand them.