I would put wheel/tires on car and use tape measure to measure from outer tire to inner lip. Leave yourself a little clearance to avoid rubbing. You can drive car on a incline (i.e. driveway) diagonally and do measurements there.
Akra Evo / MS stage 2 / MS UDP / VF Tune / KW S/O springs / Vorshlag plates / ST 380/355 BBK / ST SR34 pads / Apex Arc-8 / Nitto NT01 / Schroth Rallye 3