I've driven 10,000+ kms during the winter of 2019/2020, 90% of my driving is on the QEW/400-series highways in Ontario. Mercedes recommends 17" wheels for the GLK, but having 20" OE wheels with AMG package I opt'd to go with 19" wheels to maintain handling, and I never regretted it. The tires are quiet, comfortable, corner and turn-in well, and soak up the potholes. Although I've never had the opportunity to try it in deep snow conditions, traction in dry and wet/snow is excellent, and able to handle turbo-diesel torque in high boost conditions, allowing seamless thrust with the 4Matic all-wheel drive system regardless of weather. I've also noticed the benefit of quick recovery time when the tire hydroplanes in wet snow/slush/rain. The only downside would be a bit of tread squirm under hard/panic braking, but it's to be expected with the narrow tread blocks (Alpin A4 winter tires did the same; similar tread design); on a SUV it would be more noticeable than on a car due to more weight transfer. If you're a hard braker, then the Pilot Alpin PA4 might be the better choice. For most people, this tire is an excellent choice for urban areas. Previously, I've purchased Pilot Alpin PA2/PA3/PA4's, X-Ice3 and Alpin A4's, and await installation of the X-Ice Snow on another vehicle---I've always been happy with the performance of the Michelin family of winter tires; my number one choice if available in my tire size.
Highly recommended!