Longer lug nuts?
 

I have a set of two piece chrome 18"x8" and 18"x10" rims (sport designs from a 996) that are going to arrive today and I wanted to know if I am going to need longer lug nuts since I will be using spacers.

Yes, you should use longer bolts.

Vertex sells wheel bolts of many lengths. Tell them what size spacers you have and they'll tell you what length you need.

Do remember to knock off or remove the gray aluminum cone thingies (real technical, huh?) from your old wheel bolts and use them on your new ones.

If you don't have them on your old bolts (due to be non-factory bolts that have the cone thing built into the bolt) be sure to buy them.