Hello, I'm new here, and I have questions :-)

So,

now I also own an A8 / D4 / Bj98 / EZ 1-99 / Quattro, 2,8 V6

Now I want to exchange my built-in concert radio for my existing Becker Navi. Unfortunately, despite my search, I did not find out if my Radio Can bus has and which adapter I need. I don't need the display in the FIS, but I need the speed spiral.

Can someone help me?
and
Which wheel / tyre combinations are allowed on the car?

Where is the idle control valve in the car, the car was standing long and the idle is sometimes too low, the LLR probably hangs something.

Thank you very much in advance.

Cord