The shiny side is supposed to face the wheel. My flaps came with stickers on them to identify where they went and which side, yours did not have stickers? Personally I think they would not look as good visually with the glossy side visible from the rear as opposed to facing the wheel.
Personally I really like them and they do an excellent job of doing what they are designed for.
Personally I really like them and they do an excellent job of doing what they are designed for.