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 CS / TMS Delrin / ST 380/355 BBK / SR34 Pads / Apex Arc-8 / Nitto NT01 / APR Splitter and GT-250 Wing / Cantrell MS Half Cage / Recaro Profi / Schroth Profi II-6 / BMW Alcantera Wheel / Cool Shirt / ESS Fire / Aim Solo DL