The wheel is the metal part of the whole round assembly. A wheel is the same as a "rim"
The rubber is a tire. The wheel is the metal part, not including the tires.
I can't figure out what you want. Your stock wheels are probably 15", I don't remember exactly. Check out this thread: All about Wheels/Tires! From size to rim choices
well, most of the [IMG] code is wrong now, but the pictures are still there.