face tagging?

I am making a game, and you build cars with guns, however i am having an issue at the moment, and i do not know a solution to the problem. The issue is, that i want to be able to place things, like a tire on a block, but i dont want to be able to place things on certain faces of the tire, for example the tread on the tire. I was wondering is there was a way to tag faces, or have somthing that will work in the same way.

There are many different ways to do something like this here is what just thought of for you.