I can get a set of used one season Pirelli W 210 Snowsport 205/55R16 91H and I would like to know would they fit okay on my 2012 MINI Cooper S Countryman with no problem.
You did not tell us what size tire your Mini Cooper came with, so it is difficult to make a precise recommendation. I notice you are in Germany, and in my experience it is not unusual for cars sold in one country to use different sized tires and wheels than what is sold in other countries.
According to the specs I have, the Mini Cooper is sold with 17 inch or 18 inch wheels as an optional choice. To me this suggests that there is a possibility that any 16 inch wheel may not work because it may interfere with the brakes or some other area in the vehicle.
If you have 17 or 18 inch wheels, then, of course, there is no way that you should be mounting 16 inch tires on them, but if you do have 16 inch wheels, there is a chance that the tires you suggest might indeed be OK.
If you know that 16 inch wheels are OK for your vehicle, then check our Tire Size Calculator
and compare your original tires with the new size to see what differences would be involved and if it might be practical to consider the change.