Tomorrow (Sunday, October 23rd, 2022) is the Day of the Tread. You can see the schedule here. There is going to be a LOT of traffic around Old Town / Sawmill Market area as the Start/Finish line is on 19th street near Sawmill Market. Additionally, there is a 4k fun run that starts at 10am that goes right through Old Town, see the route below.
Traffic Overview for Old Town:
If you reference the schedule above, there are different events that will start beginning 8am through 11am. But the routes will not be officially closed until 5:30pm. It is likely that Mountain Blvd. will be closed ALL DAY. Additionally because of the 4k run, San Felipe will be closed to cars for a portion of the day.