Costco - Walmart are Sunday possibilities in a pinch.
Gotta say, I got expert RV tire service from Chuck at (Nolan's Point, formerly named the Tire Factory - same business, new franchise name)
Unless I had no choice, I would wait for Monday to see this guy in particular.
Chuck was referred and knew to recommend Cooper Tires and also added metal valve extensions . My next mod will be a TPMS system.
Nolan's Point Tires
22045 SE Stark Street
Gresham, OR 97030
(corner of Stark and 220th in Gresham)
I live in Portland, but drive to Gresham for this excellent service and competence.
And I agree with the others, Les Schwab is a winner all over the NW. But not open on Sundays.