I have a 99 CTD with 3.55 gears and Dana 80. The DRB is set at 102 tone ring and 694 rpm. This isn't right. My tires are 655 rpm. 235/85/16 31.8&quot;. What should the tone ring be set at to make the tire size and speedo match??<br>The DRB scale is 102-120 tone ring <br>rpm is from 680-694<br>The stock 215's are 683 rpm but it is set at 694 and seems correct.<br><br>What should the settings be to work.