Castor diameter 65mm, pin diameter 11mm, unloaded braked (empty chair does not roll away), loaded no braking effect noticeable.
Castors have been in use for one year on giroflex 64 office chair on oiled parquet, so far no traces. Function perfectly as a replacement for this chair.

The castors have a diameter of 65 mm

11mm yes. Probably lightly braked - chair does not roll far when I give a push on parquet, sitting very comfortably to the printer and back. Leaves no marks on parquet after 1.5 years, without base plate.