BFG KO2 35" (315 x 70 R17) Forscan Tire Size Speedometer Programming (Solved)

[Rustfish]

Saw a lot of other posts on this, but none specific to these tires. Since it took me several hours today to get the size right I thought I'd post results here for posterity.

When swapping these roughly 35" tires onto a non-Sasquatch, Forescan can be used to adjust the "Tire Circumference" setting as follows to get the speedometer back into spec. I used GPS speed from Waze to tune it and it's pretty dang close now. Note: These tires are at 40 PSI.

• Forscan - Configuration/Program section
  • BdyCM - cfg
    • Filter for tire
    • Set tire circumference to 2655 mm. It took a bunch of test drives comparing GPS to speedo to come to this size.
    • Click the "Write" button
    • Exit BdyCM - cfg
  • Fix the DTCs we just created
    • PCM initialize/relearn - Run it
    • AWD initialize/relearn - Run it
• Under Forscan DTCs
  • Clear DTCs (bottom button)
  • Real DTCs (bottom button) to confirm no DTCs

Hope this saves someone some time!

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[Umichigan1]

Saw a lot of other posts on this, but none specific to these tires. Since it took me several hours today to get the size right I thought I'd post results here for posterity.

When swapping these roughly 35" tires onto a non-Sasquatch, Forescan can be used to adjust the "Tire Circumference" setting as follows to get the speedometer back into spec. I used GPS speed from Waze to tune it and it's pretty dang close now. Note: These tires are at 40 PSI.

• Forscan - Configuration/Program section
  • BdyCM - cfg
    • Filter for tire
    • Set tire circumference to 2655 mm. It took a bunch of test drives comparing GPS to speedo to come to this size.
    • Click the "Write" button
    • Exit BdyCM - cfg
  • Fix the DTCs we just created
    • PCM initialize/relearn - Run it
    • AWD initialize/relearn - Run it
• Under Forscan DTCs
  • Clear DTCs (bottom button)
  • Real DTCs (bottom button) to confirm no DTCs

Hope this saves someone some time!

Thank you for posting this. This is the kind of thing that should be "stuck" to the top of the forum.

 

[BBQBennz]

Thanks for solving. My Sasquatch Goodyear's may even need calibrating. Currently reading 1.744% faster that I am traveling. Thus, my odometer will indicate 36,628 miles when it reaches 36,000 miles. Ford may get out of a lot of base warranty claims early as a result. Hope I am wrong.

 

[Kesker]

Thank you for being concise and accurate!

 

[BonezTheGoon]

Thank you Rustfish!!!!

Worked perfectly for the K03 LT315/70R17 tires on my wife's 2021 Badlands. Your contribution saved me all the time you clearly invested! Thanks again!!!!

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