How to use FORScan to adjust tire size

[seamonkeyd]

I have a canadian spec 2014 Ford Mustang GT. I found a spreadsheet online and a forum post explaining how to to that, however, I noticed the BCM lines are quite different.

I attached a screenshot for reference.

I recently changed to 4.10 gears and my tires are 245/45/19. In Forscan, I have two options either modify BCM lines or the other human-friendly option, but max gear ratio I can set is 3.73 and I have bunch of tire options to select from, to compensate for difference between 3.73 and 4.10 I chose the biggest tire circumference I could find from the list. After doing that, still I have a 10kmh (6mph) difference so my speeding is reading higher, which is better than reading slower at least.

I'm trying to adjust it further to make it close to regional specs (speedo must read 3~6kmh slower). I compared the BCM lines before and after changing the tires and used ChatGPT/Google Sheets to figure something out ... no solution found

[SmallwoodDR82]

Has anyone made any headway on this issue?

I have a 2024 F-150 Powerboost Platinum. Installed raptor wheels with 315/70R17 and I used the value 2741 (using FORScan 2.3.60). I get DTC U0422 and no matter what clearing or relearning I do, it will not go away (only have PCM, no TCM). I read on another post it's due to the tire circ. going over the max allowed for my truck. If that's the case any idea on how to adjust the max circ. allowed?

I went back to default value and all errors are gone but Speedo is still off.

Thanks in advance.

[SmallwoodDR82]

Update: I was able to get the U0422 issue resolved. Looks like there has been some changes on where the modification in Forscan needs to be.

I followed this google sheet and it worked perfect with zero errors and Speedometer is dead on with my Raptor Wheels (17") and BFG KO2 315/70R17

https://docs.google.com/spreadsheets/d/ ... 2133040050

I give all credit to Livinitup and Spart.

I hope this helps others with these issues.

Thanks!

[408Stang]

Rocky Rohde has a great video on you tube for programming. Worked great on my 24 F250.

I'm really struggling with my 21 f150. The TCM isn't listed in my modules. I have also learned that using 2799 is the largest tire size I can get away with on either truck.

Update: was able to program my 2021 F150 for 295 70 18 just fine. I just changed the tire size in MM and did a PCM relearn. All functions such as speed sign recognition, speed limit tolerance and all other Co-pilot functions are working properly.

The link to the video is: https://www.youtube.com/watch?v=I57ZXAL6Mys

[godsend1]

Just ran the tire change on my 24 F350, I am able to clear the TCM and PCM, but now have an AWD P160A with the wrench and CEL.

Do I just need to lower the mm size in stages until I reach an acceptable limit?

Unfortunately, I though I had backed up my cfg but was mistaken and have no backup.

2024 F350 Limited 6.7 Diesel HP went from Stock to 37's

[reshleman]

my 2018 came with 245-70-17 and i put 275-65-18's on it. Used forscan with 2558 as the cir mm. Now my speedo is off 2 mph slow. I'll never get a ticket now! I tried changing the number to 2550 to see if it would be closer... but then it wouldn't shift to 10 gear again, and it was still off 2 mph.
What say y'all?
thanks so much!

What is the max circumference on a 2017 f250? I put 2799 but I’m getting a code. Mph is accurate but I want the check engine light off.

[pkarhoff]

For those that are having trouble with the 23+ MY tire resize/relearn and the TCM code not clearing, after following the instructions to relearn the PCM, then TCM and finally the AWD Mod you will need to start the vehicle and while it is running, initiate the TCM relearn again. It will prompt you to shut the engine off to complete which you will do. Once it completes, it will prompt to turn the key on but not start, do this. Now, go clear the codes again and after cycling the power when prompted, your code should now be gone in the TCM as well.

As an FYI, some have said that 2799 is the max you can go for circ size. I have found that I cannot get anything above 2789 to work.

Also, on a 24 F250 Platinum Tremor with 20-inch rims, Falken Wild Peak RT01's (37x11.50r20) with 55 PSI are dead on accurate with 2762 as a circumference size. For every 5 PSI you increase, up the circ number by 2. At full 80 PSI you'd be at 2772.

[Jay33875]

For those that are having trouble with the 23+ MY tire resize/relearn and the TCM code not clearing, after following the instructions to relearn the PCM, then TCM and finally the AWD Mod you will need to start the vehicle and while it is running, initiate the TCM relearn again. It will prompt you to shut the engine off to complete which you will do. Once it completes, it will prompt to turn the key on but not start, do this. Now, go clear the codes again and after cycling the power when prompted, your code should now be gone in the TCM as well.

As an FYI, some have said that 2799 is the max you can go for circ size. I have found that I cannot get anything above 2789 to work.

Also, on a 24 F250 Platinum Tremor with 20-inch rims, Falken Wild Peak RT01's (37x11.50r20) with 55 PSI are dead on accurate with 2762 as a circumference size. For every 5 PSI you increase, up the circ number by 2. At full 80 PSI you'd be at 2772.

worked great except I still have a wrench but not codes or CEL.

[pkarhoff]

For those that are having trouble with the 23+ MY tire resize/relearn and the TCM code not clearing, after following the instructions to relearn the PCM, then TCM and finally the AWD Mod you will need to start the vehicle and while it is running, initiate the TCM relearn again. It will prompt you to shut the engine off to complete which you will do. Once it completes, it will prompt to turn the key on but not start, do this. Now, go clear the codes again and after cycling the power when prompted, your code should now be gone in the TCM as well.

As an FYI, some have said that 2799 is the max you can go for circ size. I have found that I cannot get anything above 2789 to work.

Also, on a 24 F250 Platinum Tremor with 20-inch rims, Falken Wild Peak RT01's (37x11.50r20) with 55 PSI are dead on accurate with 2762 as a circumference size. For every 5 PSI you increase, up the circ number by 2. At full 80 PSI you'd be at 2772.

worked great except I still have a wrench but not codes or CEL.

This is one that I have not seen until your post. What year, model, trim and engine? Also, what number did you use for circumference?

Two schools of thought for me here:

The first, try clearing all the TCM/PCM KAM values then do a relearn. Start with the ignition/power off and do PCM and when it tells you to turn the power off just hit okay as it will already be off. Next do the TCM and AWD just as you normally would. Lastly, do the TCM relearn again with the engine running and follow the prompts. After it tells you to turn the power on but not engine, clear the codes and see.

The second, sometimes there are specific values that, for some reason, the system doesn't like even though the number is below 2799. The very weird thing here is that it varies between model years from what I have witnessed.

[fuSco]

Hello.
Can I change the tire size on a 2011 Ford Kuga MK2 Powershift AWD?
Thank you.