'66 c10 help.

[cb1965]

hey guys im trying to figure out tire selection for my truck. i want to drop it and add white walls. some one did a photoshop of what i want it to look like, it will not be bagged, just drop spindles and coils.
here is what she looks like now


here is what i want her to look like


i need info on wheel with and tire selection. i've been looking at some smoothies on the summit page . they have the option of 15x6 15x7 15x8. whats the main difference, advantages? what tire size will work with either. this will be a frequently used truck. where are the best deals on tires

thanks any help is apreciated