Setting arbitrary tire sizes for speedometer calibration

[Dordogne]

275 65 20 Radar Renegade LT tire on a 2013 F-150. Spreadsheet shows 0A45. I input this and I am 6 MPH off. Speedo shows 70 and I am traveling at 76 per the GPS. I have tried the GPS calculation and still off by about the same. What in the world am I doing wrong?

As far as I know, this doesn't work on the 2014 and under F150's. I believe it is indeed stored in the BCM, but a different location. I would set your as-built back to stock in case you inadvertently changed something unrelated to the tire size.

If anyone has been able to get this to work with a 2014 and under, post up what you did so others can try and replicate it.

[harveyr4]

Has anyone found a fix for the speedo on the 2014 f150's. I have tried the configurations from the OP with the excel calculator, but i'm still off about 5-6 mph. I'm making the change in BCM 726-45-01. My tire size is 35x12.5/17 toyo. Nothing seems to make it change. Help Please

[Ahnabil]

275 65 20 Radar Renegade LT tire on a 2013 F-150. Spreadsheet shows 0A45. I input this and I am 6 MPH off. Speedo shows 70 and I am traveling at 76 per the GPS. I have tried the GPS calculation and still off by about the same. What in the world am I doing wrong?

As far as I know, this doesn't work on the 2014 and under F150's. I believe it is indeed stored in the BCM, but a different location. I would set your as-built back to stock in case you inadvertently changed something unrelated to the tire size.

If anyone has been able to get this to work with a 2014 and under, post up what you did so others can try and replicate it.

my explorer 15 has the same value in the same block you mentioned 26.45.1 as the spread sheet you shared. so this is where the circumference is stored for sure. but it doesnt match the speedo when I change it. and it gives a PCM DTC. receiving invalid data from BCM, it says. recalibrating PCM didnt remove the dtc and didnt make the speedo change.
could you help me with this please?

[fromdetroit7]

I have a 2013 F-150 XLT supercrew 4x4 w/off-road package and I bought it new from the dealer who had a 6" pro-comp lift and 35x12.5R18 Nitto tires installed. The dealership provided me with a hypertech speedo calibrator with the purchase. However, the speedo was always 5mph faster than actual speeds. The hypertech tune just wasn't accurate. When I first discovered FORSCAN and came across the various threads for changing the tire size in order to calibrate the speedo I tried just about everything I read that may apply to my situation. Nothing worked. Finally I gave up entering all the different hex codes generated from the excel spreadsheet floating around. Granted, I have a 2013 and I believe the spreadsheet was created specifically for 2015 & newer so that could have been my problem all along. Anyway, I ended up using the largest tire size available in FORSCAN (I can't remember the exact size but it started with 317) and also changed my axle ratio to lowest available which was 4.10 and BOOM!, my speedo was dead accurate. My factory axle ratio setting was 3.55, does anyone foresee any issues down the road with what I did? I really haven't noticed any difference in gas mileage or how the truck drives. I appreciate anyone's input.

[Mackey002]

Hello,

I can not clear wrench and dtc p160a after changing tire size in my 17 f150.

What is the latest fix? The relearn does not help.

[Joeface]

Hello,

I can not clear wrench and dtc p160a after changing tire size in my 17 f150.

What is the latest fix? The relearn does not help.

I have the same issue, corrected the speedo but now it keeps throwing up the wrench at startup.

[sragsdill]

Same wrench problem. Please help. I can't get rid of the wrench after changing BCM 726-12-01 to 09E7 (was 09AC). Speedo is right on the money though. I have researched all the forums, run the Module Initialization/Relearn function several times, tried to delete the TCM DTC P160A multiple times. No other DTCs exist. This is a very persistent wrench.
Vehicle info: 2018 F150 Lariat, 3.5L Ecoboost Screw, FX4, 3.55 diff, new LT275/70R18 Michelin Defender LTX M/S tires.

UPDATE: SOLVED BY UPDATING MY FORSCAN SOFTWARE TO LATEST VERSION WHICH OPENED UP THE OPTION TO "RELEARN THE TCM" ALSO.

[Slhaver]

watch this you tube video at the end will cure your issue....https://youtu.be/KFnKsSnRLZM

Same wrench problem. Please help. I can't get rid of the wrench after changing BCM 726-12-01 to 09E7 (was 09AC). Speedo is right on the money though. I have researched all the forums, run the Module Initialization/Relearn function several times, tried to delete the TCM DTC P160A multiple times. No other DTCs exist. This is a very persistent wrench.

Vehicle info: 2018 F150 Lariat, 3.5L Ecoboost Screw, FX4, 3.55 diff, new LT275/70R18 Michelin Defender LTX M/S tires.

[Mackey002]

do you have a 17 with 3.5? Because i have done what is in the end of that video and it does not work. i have also tried changing gear ratios and rollout numbers to lower the hex value and that does not work. I can not make a single change to that line of hex without the wrench and no way to clear it.

[Joeface]

As stated above, the relearn function does not change the outcome. The wrench continues to appear.