2024 Ford Ranger 2.7L Tire Circumference Calibration with FORScan 2.3.66

Sorry for the bouncy screen capture while Forscan is loading data. It gets steady at the points where changes are made. For reference, I worked in the GPS design industry for 20yrs. Your cell phones’ GPS velocity is accurate to 0.2m^2 and is even better at steady state (e.g. cruise control on flat ground); so pretty good. You can use Google Maps with a route to any destination to compare your GPS velocity to the truck’s speedometer. If the GPS velocity is higher than the speedometer, increase the circumference value. If the GPS velocity is lower than the speedometer, decrease the circumference value. Don’t trust the tire size calculator websites or the manufacturers stated value; these are ok to get a ballpark estimate (starting point), but I found that the correct value for my setup through road testing was 78mm lower than the what was provided by those resources.