It seems to be a well known issue and Mercedes is just downplaying it saying that it's normal. Check on the web for GLC wheel juddering and there are plenty reports. It seems that affects mostly the cars with the big wheels 19, 20 and above when doing tight manoeuvring with full lock. Run Flat tires are also a factor apparently.
Some get some suspension knuckles changed and that improved the situation a bit.
The German speaking colleagues on this forum will surely explain you better. Suggest opening a new topic for this issue.
Cheerio
