Setting arbitrary tire sizes for speedometer calibration

[Vale5799]

I am trying to correct the speedo on my 2019 F150 5.0. I have changed the rims and tyres but apart from being wider they are equal the the factory size (orignals 275/55/20 now 305/55/20). I used the settings from the calculator spread sheet but I still have an error. Any suggestions on how to resolve this? Thanks

[Dordogne]

What do you mean by “error” - like a DTC or a speedo error?

[Djack]

Trying to calibrate speedometer on 2012 F250. Not sure what block to program into. Any help would be greatly appreciated!

[lenko]

Trying to calibrate speedometer on 2012 F250. Not sure what block to program into. Any help would be greatly appreciated!

Could be the middle 4 numbers of 726-45-01 (BCM). Just checked Grandson's 2012 Ford F 150 and his 726-45-1 is xxxx 0988 xxxx, which shows the 0988 definitely denotes his tire size and this is what you have to determine is yours according to the spreadsheets in this thread.

[black150]

I did this and didn’t work !

Ok.

1. Launch Forscan and connect to truck while running.
2. Click on the Chip icon, aka the "Configuration and Programming" tab.
3. Click on "BdyCM (AS BUILT format)"
4. Click on the Play icon, aka the "Run Service Procedure" button, on the bottom.
5. Read pop-up window and hit "Ok"
6. Click on the "Safe All" button at the bottom and save the stock data.
7. Click on the stop button, aka "Stop Service Procedure" button.
8. Click on the "Configuration and Programming" tab up top.
9. Click on the "BdyCM" line
10. Click on the Play icon, aka the "Run Service Procedure" button, on the bottom.
11. Click on the "Tire Size" line.
12. Click on the "Edit Selected" button near the bottom left.
13. Select other tire size and click ok.
14. Click on the stop button, aka "Stop Service Procedure" button

Repeat steps 1 through 5 and compare line by line and you should be able to find what the service procedure changed. That will be the tire size field.

[CombatDork]

Well it is 2 years old and something may well have changed.

What are you trying to do exactly?

Set an Arbitrary Tire Size or Select from the Factory size options?

[kalongauto]

Have you insisted that your method is correct now? because xxxx is a representation of two independent hex lines
4/16/2020

[CDWALKER25U]

Trying to correct my speedo for my 2015 F150. Currently have 35x12.50x22r Gladiator Comp M/T

[Austinrharris0498]

Need help. I used the google sheets calculator you made to calculate tire size code. I have a 2017 mustang. I have 256/50r19 in the rear. So I used that size to calculate. The fronts are 254/40r19. When I wrote the new code in the speedometer was correct but I was experiencing throttle cut out at about 3k+ rpms in third gear or higher. Any ideas ?

[rcrayj]

I have a 2013 F150 and I adjusted line 726-45-01 to correct my speedometer.
I used the spreadsheet to calculate my tire size difference and used the code it spit out. I am within 1 MPH of GPS speed.