My Regamasters are 18x9.5 +35 and they are within 1mm of my Stoptech ST40 caliper face. My BBS RGRs are effectively 18x9.5 +37 and they're also within 1mm of the caliper face. The 18x8 +42 Weds would sit roughly 25mm further in than either of my wheels, so assuming the spoke design is similar it could be realistically anywhere from 20-30mm or more.