He was smart. They do tires. You are not getting your oil changed there.
Go to Firestone or Goodyear unannounced and prepare for a 5 hour wait. Plus DT will honor any advertised price.
He founded DT about the same time McDonalds was founded. Both created to be highly efficient and low cost. I enjoyed the Ray Kroc movie “The Founder” a couple weeks ago. Fascinating dive into the psyche of a seriously driven businessman.