I finally found out the problem. Because I don’t like when I don’t understand, I’ve analyzed the model to the pixel… And found out a weird stuff. I found a border on the back of the wheel, which should not be there. After having deleted those, I finally understood what was happening.
It seems that for a reason I don’t know, I wrongly attached the wrong vertices. Or did a wrong extrusion at the very start of the modeling process. Nevertheless, the vertices were wrongly attached, and the shape was curving in an angle of nearly 190°, which can’t be smoothed by the hypernurbs (as long as I know, hypernurbs can handle up to angles of 180°). I totally deleted those faces, and restarted the extrusion. The welded the point together, and it is now working as it should…
It was a mistake of mine, and I’m glad having it found.
The only thing left now is that I notices some vertices still there, no face being attached (I deleted the faces, not the vertices). Is there any method to clean those “lost” vertices ?
Thanks a lot
Vampyre