How to use FORScan to recalibrate speedometer for bigger tires

[ENG430]

Is changing tire circumstances will change and recalibrate the transmission to the new tire size.
One of my friend said that I should reprogram the gear transmission if I change to bigger tire size or it will damge the gear box.

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[UGADawg96]

I upgraded from 275/60r20 to 285/60r20 and the speedo is more accurate now. It was off from the factory.

 

[ENG430]

Is changing tire circumstances will change and recalibrate the transmission to the new tire size.
One of my friend said that I should reprogram the gear transmission if I change to bigger tire size or it will damge the gear box.

Any help please?

Should I change the gear ratio when upgrading to big tires?

 

[additionsola]

Any help please?

Should I change the gear ratio when upgrading to big tires?

It all depends on tire size and what your gear ratios are now... going up a few sizes isn't going to hurt anything. Hell going to 35s won't hurt anything, but you're going to kill your torque/low-end power. On my Chevy I went to 35s (from 31s) and definitely benefited from re-gearing. On the Ford, I opted for the 3.55 gears, I went to 33s and won't touch the gears.

 

[ENG430]

It all depends on tire size and what your gear ratios are now... going up a few sizes isn't going to hurt anything. Hell going to 35s won't hurt anything, but you're going to kill your torque/low-end power. On my Chevy I went to 35s (from 31s) and definitely benefited from re-gearing. On the Ford, I opted for the 3.55 gears, I went to 33s and won't touch the gears.

The tires installed now in my F150 from Ford is: Pirelli 275/60/20 .

Im going to install: BF 285/55/20 .

is it safe to keep the same gear ratio that comes from the manufacture or should change it?

 

[additionsola]

The tires installed now in my F150 from Ford is: Pirelli 275/60/20 .

Im going to install: BF 285/55/20 .

is it safe to keep the same gear ratio that comes from the manufacture or should change it?

You're actually going down in tire size....

You'd be A-OK keeping stock gears.

 

[Eric12775]

What about when changing axle gearing? I’m planning on installing a 3.73 posi in my rear and I’m probably going to go up from 17s to 22s.

 

[itsdchz]

You'll be able to calibrate your speedometer with the free FORscan software, a portable Windows device, and an appropriate ODB II adapter. The best adapter to get is the ODBLink EX for about $50 on Amazon. Stay away from the chinesium ones.

I have instructions for doing this here: https://www.mustang6g.com/forums/th...ometer-error-no-flash-or-tune-required.67564/

Pay close attention to the need to do a PCM and TCM relearn in order to clear DTC's.

Also, for the 2021+ F150 the address location has changed. Instead of:

726-12-01 xxxx ABCD xxxx

It is now split between two lines:

726-15-01 xxxx xxxx ABxx
726-15-02 CDxx xxx xxxx

The same values from my calculator linked in the Mustang 6G thread will work in the new location.

Help??

I have gone from 265/60/20 stock Hankook to 275/60/20 more aggressive Cooper Discoverer ATS. When pulling up my info in a 2021 Powerboost, under BdyCM, I look at the appropriate fields but they do not match:

Stated info from OP: 726-15-01 xxxx xxxx ABxx - This field already contains the correct value in my vehicle: xxxx xxxx 09xx (based on code gen, both sizes have this same value present)

Stated info from OP: 726-15-02 CDxx xxx xxxx - This field only has the parameters in 2 segments, ie: F3xx xxxx

Based on my stock configuration, I should have 726-15-01 as: xxxx xxxx 09xx - this is the same for new parameters as that value did not change - OK

What would I change for 726-15-02? My stock parameters are: F3XX xxxx (no 3rd segment) (the stock parameters in the HEX generator suggests that based on 265/60/20, I should be CD- CDxx xxxx xxxx, even though F3 is present on as built parameter)

The Hex generator states I should have F2 as the new value, however when I replace the F3 to the new F2 value, it states that my checksum is wrong, so I did not write The code and perform the DTC check.

Any ideas if the Powerboost BdyCM and 726-15-02 is different on 2021+ and should only contain 2 segments, not 3, and if I write the F2 value vs F3, if this is truly for the tire size?

Thanks in advance.

In summary:
As built on 2021 PowerBoost - came with 265/60/20 Hankooks- Added 275/60/20 Cooper

I have stock configuration:
726-15-01: xxxx xxxx 09xx
726-15-02: F3xx xxxx

Hex builder states I should have stock configuration as:
726-15-01: xxxx xxxx 09xx
726-15-02: CDxx xxxx xxxx

Hex builder with new tires:
726-15-01: xxxx xxxx 09xx
726-15-02: F2xx xxxx

Forscan v2.3.46

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