Discount Tire is not everywhere, but they are very well established in the Southwestern US. I have been dealing with them for a very long time and my wife's car, my truck and the Airstream all have tires from Discount Tire.
Last year I discovered a bad tire when I setup my trailer in Colorado Springs. I called ahead to a store in Fort Collins and had a replacement waiting for me. I could have had it replaced in Colorado Springs, but decided to get to my destination on the spare instead. They were not able to match the brand but did match the type and size. When I returned home to Phoenix, I had that tire replaced to match the others.
Here is the commercial that Lumatic mentioned in his post:
YouTube - Discount Tire Little Old Lady