Winter tyres / winter complete wheels

Sorry that I already (again) put the topic on, but it just doesn’t leave me any rest at the moment. I would like to equip my existing original BMW 20″ BMW rims (728 Bi-Color) with 20″ winter tires, which also have a BMW “*” mark, but unfortunately there is not the one at 20″ WinterREIFEN. However, since I am a “branded” child with the topic tires (SUPER sensitive to imbalance), it looks like I have to buy an original 19″ WinterREDER set. for winterers/reifen at 20″, or do you advise me to buy the 19″??? As mentioned, I am sensitive to the topic of running calm/unbalance SUPER…