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How to Recalibrate Your Ford Speedometer for 37” Tires Using FORScan

  • Writer: Dan
    Dan
  • Feb 21
  • 3 min read

Updated: Mar 14


When we installed 37” BFGoodrich tires on our Ford, it completely transformed the truck.


It also threw our speedometer off by about 6%.


And if you’ve followed The Baker Adventures for any length of time, you know we track fuel economy, performance, and real-world numbers pretty closely. A 6% variance isn’t “close enough.”


So we fixed it.


This guide walks you through exactly how we recalibrated our speedometer using FORScan — including the prompts you’ll see, the values we used, and how we solved the dreaded TCM P0160 code.


Huge shoutout to Rocky Rohde for laying the foundation. We just added the Baker Adventures real-world troubleshooting spin to it.


What You Need


  • OBD2 adapter compatible with FORScan

  • Windows-based laptop

  • FORScan software installed

  • Your new tire circumference in millimeters

For our 37s, 2799 mm worked perfectly.


Step-by-Step: FORScan Speedometer Recalibration


Step 1: Change Tire Circumference in BdyCM


  1. Connect FORScan to your truck.

  2. Go to Configuration and Programming.

  3. Select Body Control Module (BdyCM).

  4. Find Tire Circumference (write down your original value — ours was 2631).

  5. Change value to 2799 mm (for our 37s).

  6. Click Write.

  7. Cycle ignition off and back on when prompted.


You will likely see warning messages at this stage — that’s normal.


Step 2: PCM Module Relearn


  1. In Configuration, select PCM Module Relearn from Central Configuration.

  2. Run the procedure.

  3. Follow ignition prompts carefully.


You’ll be asked to cycle ignition during this process.


Step 3: TCM Module Relearn


  1. Select TCM Module Relearn.

  2. If it fails initially, ensure:

    • Ignition is ON (engine not running)

  3. Follow prompts exactly.


This step is where most people run into issues.


Step 4: AWD Module Relearn


  1. Select AWD Module Initialization/Relearn.

  2. Follow ignition prompts.

  3. Complete procedure.


Step 5: Clear All DTC Codes


  1. Go to DTC tab.

  2. Reset all codes.

  3. Cycle ignition as prompted.


At this stage, you may see:

TCM Code P0160 — Control Module Configuration Error


If that code does NOT go away, continue below.


Fixing TCM Code P0160 (This Is the Step Most Videos Skip)


If P0160 persists, here’s exactly what worked for us:


Step 6: Full Power Reset + Running Relearn


  1. Disconnect FORScan and close the program.

  2. Turn ignition OFF.

  3. Open the driver door.

  4. Wait until all screens go black.

  5. Restart FORScan and reconnect.

  6. Start the truck fully (engine running).

  7. Perform TCM Relearn again while engine is running.

  8. When prompted near the end, shut the truck off.

  9. Turn ignition ON (engine not running).

  10. Clear DTC codes again.


Code gone.


This was the missing piece.


Confirm With a Test Drive


We verified accuracy using a Garmin GPS.

  • At 50 km/h → reading fluctuated between 49–49.6 km/h

  • At 100 km/h → fluctuated between 99.8–101 km/h


That’s dead on.


And the only light left on the dash?


Low washer fluid. (Welcome to Alberta winter.)


Why This Matters


Running incorrect speed calibration affects:

  • Fuel economy calculations

  • Transmission shift points

  • Odometer accuracy

  • Potential long-term drivetrain behavior


If you're running 37s — or any oversized tire — recalibration isn’t optional. It’s responsible ownership.


Watch the Full Walk through



Video: How to Recalibrate Ford Speedometer for 37” Tires Using FORScan


What Should We Do Next?


Now that the 37s are dialed in…

  • Winch?

  • Camper setup?

  • Full overland build?


Drop a comment and let us know what direction this build should go.

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