1) Plug ECRI Device into OBD Port2) Tap ECRI app on smart device3) Bluetooth will connect automatically4) Tap "Tire Size" (first option)5) Enter Tire Size (Pro-tip: The size on the sidewall isn't accurate because the tire squishes from the weight of the vehicle. Subtract 1" from the sidewall size without measuring.)6) Tap "Write Programming"7) Confirm Updates8) Turn Engine Off, Remove Key, Open Door, let Modules Power Down