Should be on that back of the rims. Something like "8.5Jx18H"
edit: Oops, you asked for offset. Again, it should be on the back of the rims (either on one of the spokes or near the center). Example: ET40 or 40ET.
Imola Red / Imola Red ///M5
E60 SSK, Dice iPod, Illuminated ZHP knob, MKIV, Euro Armrest, GT ExhaustDaily:
BCR Coilovers, 19x10 + 19x11 Rial Daytona Race, Michelin Pilot Super Sport
'04 E55 AMG Brilliant Silver on Anthracite leather
'96 318i Alpine White on Black
'01 330Ci Titanium Silver on Coral Red
'96 328i Jet Black on Black