My last 3 rear tire changes: 9,000; 11,600; 10,839. Averaging the two highest mileage changes the number is 11,220 miles. So, I am going to say I change my tires at 11,220 miles. The 9,000 mile change was done early due to an upcoming longer trip.
Keep in mind I do not run the tire to the wear bars as each of my trips is 1,200 highway miles. I use the 2 mm tread depth specification from the Service Manual as a changing guideline. So, I change my tires between the 2 mm tread depth specification and the wear bars. I am not a fair weather rider and ride in (heavy, moderate, and light) rain 40% of the time.