First a brief description of the rules in the three countries you intend to visit:
In Germany, it's only mandatory to have winter tires (or all-seasons tires with the “M+S” symbol) if there is snow or ice on the road, not during the whole winter season.
In France, there is no general obligation to have winter tires but on some (mountain) roads snow chains or winter tires might be mandatory in case of snow (in this case there would be a sign like this one). Occasionally (e.g. on roads leading to a ski resort when the weather is bad), the police (mostly the gendarmerie) will even filter cars and check your equipment to make sure nobody gets stuck and blocks traffic further up.
In Switzerland, there is to my knowledge no specific regulation but you are still responsible of making sure it is safe to operate your vehicle and you could therefore have trouble with your insurance if you decide to go on a mountain road without any equipment and cause an accident.
If you stick to the main road network, don't plan to go to remote mountain areas and are able to wait out the occasional bout of snowy weather, you can legally drive through all three countries without winter tires (although they are useful even without extreme weather because they are usually better than summer tires when the temperature is low and the road is wet).
In any case, it's not because winter tires are useful or mandatory in some parts of the country that all rentals will have them or that you will not be charged extra to get some. For example, it's virtually impossible to rent a car with winter tires in Paris and only some rentals have them at the airport in Lyon (which is closer to the Alps). In Italy, when it's actually mandatory to have “winter equipment” in some provinces during the whole winter season, car hire agencies typically provide snow chains (and charge for it) but not necessarily winter tires.
You will have to ask around and compare prices directly, there is no general rule (besides, a cheap rental plus some cheap snow chains could still be cheaper than one that comes with winter tires).
