Setting arbitrary tire sizes for speedometer calibration

Testing new functions
lenko
Posts: 577
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

In BCM run Module Configuration - NOT the Asbuilt. A screen will show up listing various categories that you can click on and change.
Scroll down and see if there is a tire circumference line with a number in mm - (I have 2174). Click on the line and change the number to whatever your tire circumference is and then hit write and follow prompts. Then you can run a relearn in PCM and also remove any DTCs that show up.
rbentnail
Posts: 77
Joined: Sun Aug 16, 2020 1:10 am
Vehicle: 2013 F150STX 4x4 5.0

Re: Setting arbitrary tire sizes for speedometer calibration

Post by rbentnail »

2013 STX 5.0 4x4.

Finally got my speedometer corrected with Forscan following a tire size change:

- For me it was not as described above with changing a number or whatever. I highlighted BCM (Non-As Built one) and clicked the play arrow. Click the CONFIG tab at the top and you'll see a list of stuff. Scroll down to Tire Size and click. A list of tire sizes came up, I picked what I have. Click Write.

- Do a PCM reset, back in the list of modules, all the way at the top. Follow the on-screen instructions, very simple. This didn't show up before so I uninstalled Forscan and re-downloaded the latest version. Poof! There it is!

- Clear DTC codes.

I was prepared to use the Tire Size Calculator and the As Built module but didn't need to. I still have no idea which parameter to change- some say 726-12-01 & others say 726-45-01. I was prepared to change tire size as above and see which changed but luckily I didn't need to.
lenko
Posts: 577
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

For 2013 vehicles it's in 726-45-01.https://docs.google.com/spreadsheets/d/ ... 1741285730. In my 2015 Lincoln MKC it's in 726-12-01. In either one it's the middle 4 figures that give the tire setting in hex. I checked it out on the Grandson's 2012 F150. If you convert that hex to decimal you get the tire circumference. The Lincoln did not have the size in the list you indicated so I had to use the tire calculator and enter those characters, but that didn't work for me so when the later Forscans came out the tire circumference setting was available in the BCM - not asbuilt. That did correct my speedometer.
It may work for the person I replied to as it's a later model and being a Transit he may not have the tires as for the F 150s. Being his is a 2019 it may not work for him but he can look. This I post is just so we all can learn more and more.
It's good that entering the tire size worked for you.
al.mo
Posts: 2
Joined: Mon Jan 18, 2021 3:11 am
Vehicle: F250 XLT 6.7-2019

Re: Setting arbitrary tire sizes for speedometer calibration

Post by al.mo »

Here is my problem, when I try to reset the tire size and perform the function none of the tire size configuration’s in the module will work. So I can’t get past even riding the module for the tires as I have. Has anyone else put 35x12.50x17’s on their 2015 F350 Dually? Mine is a Lariat FX4 which I’ve upgraded to the sync3.

This is what should have worded
Toyo Open Country MT 35x12.5x18 726-12-01 xxxx 0A50 xxxx

So I then tried everyone of these and none would work.

BFG KO2 35x12.5x20 726-12-01 xxxx 0A7F xxxx Freeseframe
Nitto Ridge Grapplers 35x12.5x20 726-12-01 xxxx 0A57 xxxx dominatorlp
Toyo Open Country A/T 35x12.5x20 726-12-01 xxxx 0A8F xxxx Kaye Kolb Jr.
Toyo Open Country MT 35x12.5x18 726-12-01 xxxx 0A50 xxxx Timc74
Nitto Ridge Grapplers 35x11.5x20 726-12-01 xxxx 0A3D xxxx gonethinkn
BFG KO2 34x10.5x17 726-12-01 xxxx 09FF xxxx 17x7 (Dually) ZooDad
BFG KO2 315/70/R17 726-12-01 xxxx 0A68 xxxx robbieg
BFG KO2 305/65/18 726-12-01 xxxx 0A21 xxxx DeltaNu1142
BFG KO2 285/70/17 726-12-01 xxxx 09E7 xxxx jpeckinp
Cooper AT3 275/70R18 726-12-01 xxxx 09E7 xxxx Scott91370
Falken Wildpeak A/T3W 275/70R18 726-12-01 xxxx 09E7 xxxx waphilips
Michelin LTX A/T2 275/65/20 726-12-01 xxxx 0A45 xxxx TX-FJuan50


Would wheel size make a difference I have Nitto Ridge Grapplers 35x12.5 but with 18s and not 20s. Also what about the offset, not thinking it would make a difference, but i'm new to forscan well and would like some help with getting my MPH set. Also new to forum so not sure i replied correctly. Anyways and help would be great. Thanks!
al.mo
Posts: 2
Joined: Mon Jan 18, 2021 3:11 am
Vehicle: F250 XLT 6.7-2019

Re: Setting arbitrary tire sizes for speedometer calibration

Post by al.mo »

Also being a F250 would that make a difference since the code is for f150??? Thanks
rbentnail
Posts: 77
Joined: Sun Aug 16, 2020 1:10 am
Vehicle: 2013 F150STX 4x4 5.0

Re: Setting arbitrary tire sizes for speedometer calibration

Post by rbentnail »

As I stated above, just changing the tire size had no effect for me. I had to do a PCM Relearn afterwards. Did you do that?
lenko
Posts: 577
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

Once you write on that line, clear DTCs if any and do a relearn. That may help. If you have the tire circumference in the BCM (not asbuilt) enter that number there and then hit write, clear DTCs and then do a relearn. It seems to be more precise that way and will correct the 726-45-01 (Older Veh) or the 726-12-01 (Newer). This does the same thing as the tire calculator.
mrpositraction
Posts: 5
Joined: Sat Jan 16, 2021 8:46 pm
Vehicle: 2019 Ford Expedition MAX, 3.5L Ecoboost

Re: Setting arbitrary tire sizes for speedometer calibration

Post by mrpositraction »

2019 Ford Expedition Max XLT 202A

Anyone successfully adjusted tire size to correct Speedo? I've read the thread, have the latest version, changed the line the BdyCM (As Built) and the other BdyCM, cleared codes, and done a PCM relearn and the wrench doesn't go away until I change it back to factory setting.

I've tried the NGauge, SCT BDX, and now the forscan with no avail. I am running 275/85 18 Nitto Ridge Grapplers

Tried 0A80 from the calculator
Tried 0A50 from the table of others
Tried 2779 for the tire circumfrance

Wrench everytime
lenko
Posts: 577
Joined: Sat Dec 24, 2016 6:40 pm
Vehicle: 2015 Lincoln MKC, 2006 Mustang GT, Saleen 530 HP

Re: Setting arbitrary tire sizes for speedometer calibration

Post by lenko »

2779 gives you a hex of 0ADB. That's what you can try in the BCM line. Then clear the codes and do the PCM reset. https://www.binaryhexconverter.com/deci ... -converter.
mrpositraction
Posts: 5
Joined: Sat Jan 16, 2021 8:46 pm
Vehicle: 2019 Ford Expedition MAX, 3.5L Ecoboost

Re: Setting arbitrary tire sizes for speedometer calibration

Post by mrpositraction »

I just tried that and while changing it to 0ADB changed the mm circumference to 2779 I still got the wrench.
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