I'm staying in Cortina d'ampezzo for three nights without a car. Renting a car is not an option for me for this trip for several reasons. I'm hoping to hike Tre cime, Lake sorapis, and maybe the 5 torri. I read on the dolomites bus website that the summer bus schedule ends a few days before my trip, and am now concerned I won't be able to go to any good hikes. Any advice on getting around?

We've booked a trip to the Dolomites for December and had the same concerns, as we'll not have a car. I contacted the various tourist offices and they helped considerably.

Suggest you do the same:

https://www.dolomiti.org/en/cortina/information-office/

As a general rule public transport is never a problem in the province of Bolzano/Bozen, but it can get a serious one in the province of Belluno.