offset questions?

i dont know much about offset or any of that stuff so i was wondering about what offset we could run on the 3geez? i want to buy some konig rewinds to give it that old school look but i want them to have a deep look to them to kind of like these:
http://images.search.yahoo.com/image...sigb=12q211e6o
even if offset doesnt effect this i will still want the rewind as they are cheap and still look decent but they come in sizes:
15" 7"wide 20 offset
15" 7"wide 40 offset
so which ever one would give me the deepest look ill buy after the swap but i want to get my shopping list together :)
so somebody explain which ones is which

The +20 offset rims will stick out about an inch past the fenders. The +40's will sit about flush with the fenders, but it won't have a huge lip on it. You could always run the +20's and build some custom wide body fenders like what the AE86 guys do.

ok ill probably go with the 20" then