those wheels are SSR professors 18x9.5 +12
18 = rim diameter
9.5 = rim width
+12 offset means; if you were to cut the rim in half the distance from the exact middle of the rim to where the bolts are is 12mm
if you dont really understand it, just google "wheel offset" and you will find something :)
as a general rule, on dished rims the lower the offset, the deeper the dish.