Most car rental companies in Germany and Europe equip their rental cars with winter tyres in good time or use all-weather tyres suitable for winter use all year round.
However, it is not the rental company that is legally obliged to do this, but the driver. If a vehicle inspection reveals that you are driving a rental car in snow and ice without winter tyres, you and not your rental company will have to pay the fine.
When booking, you should therefore check whether winter tyres are included in your offer or can be booked in addition.
Even if there is no legal obligation, it can be useful to have winter tyres or all-weather tyres suitable for winter use on the rental car, depending on the destination. If you are planning a winter holiday in the snow, you should add them.
Note: You can only make sure that your rental car has winter tyres. You cannot influence whether these are winter tyres or all-weather tyres suitable for winter use. However, both tyre variants are recognised as winter tyres in Germany and will get you safely through the cold season.
All the latest information on this topic is provided by ADAC (General German Automobile Club) and other organisations.
The following article relates to this topic:
How do I find out whether winter tyres are included with a rental car?