That is the front wheel. The argument is about the rears.
hollus wrote:I forced the contrast and brightness in powerpoint, please feel free to do a better job with a proper program.
The "thing" seems to reflect light to a small extent along it's whole width, exactly aligned with the quasi-specular reflection in the gray part of the wheel rim, but less sharp. To me that says is is a band of a black material.
What I see is not
"exactly aligned with the quasi-specular reflection in the gray part of the wheel rim," but at an offset in the direction of the tyre, which further reinforces the cavity argument. Considering the limited space there is to play with, any cavity would need to be quite shallow; a shallow cavity would give a reflection that's offset from the line of reflections on the inside of the rim..
Possibly, such a cavity might be filled with a foam or honeycomb made of a heat conducting material (eg graphene) that increases the area of contact between cooling air and the rim for efficiency; but that's pure speculation. However, such a filling would scatter light and lead to reflections that are diffuse (again, pure speculation).
The most important question is if such a cavity is legal.