Nearly all BMW and other German-made cars come equipped with Summer Passenger tires, as many Europeans use winter / snow tires during the colder months. The all-season tire and M+S (Mud and Snow) branded tire are mostly used in North America as a convenient compromise between two categories of tire compounds to avoid having to switch back and forth between tires as the seasons change. To learn more about the differences in snow traction between M+S branded tires, all-season tires and winter / snow tires, read "How to Confirm a Winter Performer."
From a practical standpoint, summer tires will perform best when temperatures are in the mid 40s (F) and warmer due to the fact that the tire's rubber compound remains flexible. The rubber compound of all-season tires can stay flexible until temperatures get close to just above freezing. Therefore, an all-season tire is recommended in areas of the country that see cold mornings and nights and receive light snow accumulation. And while an all-season may get you through every season safely, the confidence and traction of a winter / snow tire is worth the investment.
If you live in a part of the country where you don't know what type of tire would work best for you, take a look at our Tire Decision Guide.