I heard a rumor that there is a legal requirement for bicycles in Germany to have treaded tires. I found this quite surprising and took a look at the regulations:
StVZO §36 (3) requires treaded tires with a minimum depth of 1mm on motorized bicycles (E-Bikes), but has no requirements on regular bicycles.
However, StVZO §63 states that the legal requirements regarding tires (and other aspects) for motorized vehicles shall also be applied to "other vehicles", which include bicycles (or not?). In other words, the requirements for car tires also apply to bicycle (non-motorized) tires, which includes a tread pattern with a minimum of 1.6mm.
This would mean that most non-MTB tires (including tires for road, touring, or even gravel) are illegal to use on non-motorized bikes, and that almost all ordinary city-bikes sold aren't street-legal without changing tires. This seems hard to believe, is it true?