Use this website/calculator. It was a critical tool I used to play with offsets/wheel sizes when I was choosing wheels for mine. It works really well. Use it to determine the OEM spec for the GLE wheels and compare it side by side with the GLC offsets and you'll have your answer. It is 100% spot on. PS - don't be afraid to get those wheels out to the edges of the fender lips - it really helps push the stance of the GLC the closer those wheels/tires get to outside edge of those fenders. There's plenty of room there. Good luck! https://www.wheel-size.com/size/merc...lass-amg/2018/
If you use a different size wheel (21 vs. 22), etc. you may have to have the ABS reprogrammed. I ran a different sidewall height 21" on my GLC63 and it caused all sorts of funky things to happen under full acceleration.
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.