Reflection areas on texture

Hello,

I have a wheel model. It's use Reflected Diffuse shader and only one texture and only one material. So it should seen like that, right?

But it's seen like that:

I'm really curious about that. What is the name of this technique? I want to search and learn this texturing technique but i don't know it's name.

When I add black texture on wheel material:

You see, texture is completely black. But why material not black completely? This is the question. What is the name of this technique?

Now we see with original texture:

It's really awesome.