3.5" body drop and 18's...what offset?

I have an 89 toyota bodydropped 3.5" and im gonna get 18's. it looks like i need a 40mm offset, is that right. also what size tires are you guys running? im thinking a 215/35. its a hair under 24" tall and its a more common/cheaper tire.I plan on ordering rims/tires online so i wanna be sure to get the right size.I like to give local shops business but i'll be saving hundreds of dollars by doing it online.