I bought some used winter tire a couple weeks back and it never even crossed my mind that the center bore would be a different size because they looked the same. My car has a 56.1mm center bore while my winters have a 55.1mm center.
Can I just dremmel out the center to fit or do I need to take them somewhere to be done professionally?
Nah I wouldn’t remove material that is structural.
And you will be unlikely to get it balanced, damaging other parts over time.