I have a Q5 with wheels, size 8.5Jx20.
These wheels consists of 2 parts, connected with 19 screws.
Between both parts, dirt gets accumulated, and flows over the wheel when these are wet.
How to solve this? Can I remove the upper part (removing 19 screws) for good cleaning from time to time?
If this is a true 2 piece wheel, then the assembly bolts are not reusable; once they have been torqued to the required spec (at initial assembly) the actually stretch a little bit. If you were to remove them (and then find out what the required torque should be for reassembly) they would most likely snap or be weakened to the point of likely failure.
If its just a trim ring, then that's a different discussion but it sure doesn't look like a trim piece to me