I was running at 68mmpr with a tekin RS and duo2 13.5, but thats our track layout and that speedo. I am no expert but it was fine for me. Also 80mmpr for the 17.5 and 52mmpr for 10.5 so somewhere between the 2 was about right.
1/12 scale single cell.
I like the 17.5 at 3.6 inches with the SXX SS speedo. I am at 2.43 inches for the 13.5, but I have some more work to do on that one. Black Diamond speedo will require different rollouts. Don't know about the Tekin.