Just ran the Hypertech Speedometer Calibrator to adjust the tire size for the new tires, BFG KO2's 285/65/20 and received the following trouble code upon it's initial setup:

DTC#1 B1215

Any idea why/what would cause this code? Is this something that I should have the dealership look into?

 

Found that the trouble code = B1215 Running Board Lamp Circuit Short to Battery

Anyone else have this issue after swapping out fog lights or making any other modifications?



Useful Link for Ford trouble codes: https://edgeproducts.com/app/uploads...cle-pdf-41.pdf

 

I got this the first time I used the hyper tech too. I just cleared it and continued. On my second tire size iteration I did not get it. There was no physical problem.

 

What size are you inputing for tire size? Based upon no changes in tire size, initially I appeared to be 3-5mph slower when comparing to GPS.

I have BFG KO2's 285/65/20 and initially tried 34.5" based upon the tire charts, but that seemed to put me 3-4mph faster. Just changed to 33.25" and will see how that works over the next couple of days.

 

I'm at 33" setting for a 35x12.5x20 Toyo RT tire which is about 34.7" tall. Speed verified by separate GPS

 

Thanks! I dropped down to 33.25" and seem to be +/- 1mph difference. Sounds like 33" is the right number.

Any explanation for why the tire charts indicate a 285/65/20 tire is 34.5", however when measuring the distance from ground to top of tire = 33.5"? I know the tire is loaded by the vehicle, but that is a difference of 1.0".

 

Tires aren't round once loaded, they deform. Pressure & sidewall height dictate how much. Measure your diameter left to right and it'll be closer to 34.5