Recalibrate speedometer for larger tires?

[Blueox76]

Is there a way to change the speedometer to account for larger diameter tires?

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[Johnkn]

What size tires?

If going from a 225-65-17 to a 235-65-17 within the same brand/family for example, the speed difference at 60 MPH is only ~1 MPH and hardly worth a change......


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[TJ2023]

Is there a way to change the speedometer to account for larger diameter tires?

I think you can with Forscan, but every time your truck gets the pcm updated it will reset to factory.

 

[Quest]

Forscan can do it

 

[matmondro]

Yes, using Forscan. There is a limit to how large it will go though, specifically a circumference of 2270 mm.

Calculate your new tires' circumference in millimeters, then multiply by a squish factor of about 97%. If that new number is over 2270 mm, then just put that in and call it a day. If it's less than 2270, then just enter whatever number you got by doing that calculation.

 

[Cancunbadlands]

Forscan can do it

 

[daggerNC]

Is 2270mm the correct FORSCAN limit for 2025 Hybrids? My factory 225/65-17 shoes are 2273mm circumference.... (also one of the factory model/option combinations have 225/55-19's which has a circumference of 2294mm) I'd like about a 1" lift for my '25 Hybrid XLT, and was considering putting 225/70-17's on which would give me a 0.9" lift, but those have a 2344mm circumference...? Has it been confirmed that Ford engineering specifies a "squish" factor? I haven't hooked up FORSCAN yet to my Mav, but would it show the actual (current) value set from the factory? (Sorry if this was discussed/verified already.)

 

[CaliMav68]

I went from 225/60/18 to 245/60/18. Made a 1.5% difference in real world use. (About 1 mph at freeway speeds)

I personally feel you shouldn't give it another thought. Unless you like to tinker!

 

[Johnkn]

Is 2270mm the correct FORSCAN limit for 2025 Hybrids? My factory 225/65-17 shoes are 2273mm circumference.... (also one of the factory model/option combinations have 225/55-19's which has a circumference of 2294mm) I'd like about a 1" lift for my '25 Hybrid XLT, and was considering putting 225/70-17's on which would give me a 0.9" lift, but those have a 2344mm circumference...? Has it been confirmed that Ford engineering specifies a "squish" factor? I haven't hooked up FORSCAN yet to my Mav, but would it show the actual (current) value set from the factory? (Sorry if this was discussed/verified already.)

Lift math above is wrong....

A 225-65-17 tire is approximately 28.5" tall
A 225-70-17 tire is approximately 29.4" tall
Difference is .9" in height
Lift difference is ~.45"

Also, virtually zero major tire companies manufacture a 225-70-17 tire.


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[daggerNC]

Lift math above is wrong....

A 225-65-17 tire is approximately 28.5" tall
A 225-70-17 tire is approximately 29.4" tall
Difference is .9" in height
Lift difference is ~.45"

Also, virtually zero major tire companies manufacture a 225-70-17 tire.


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Absolutely right on the lift difference (not enough coffee yet?), and tire selection. Going to 235/70-17 would give me a 0.75" lift, but this raises the original question of being able to calibrate with FORSCAN at this size (2390mm)?

 

[Johnkn]

Absolutely right on the lift difference (not enough coffee yet?), and tire selection. Going to 235/70-17 would give me a 0.75" lift, but this raises the original question of being able to calibrate with FORSCAN at this size (2390mm)?

Within the same manufacturer/tire family, there is only approximately a .9" difference in height between a 225-65-17 and 225-70-17 tire. That's .45" of lift.

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[daggerNC]

@Johnkn - I asked about a 235/70-17 tire which gives a .75" lift..

 

[Johnkn]

@Johnkn - I asked about a 235/70-17 tire which gives a .75" lift..

Here's your original post #7 where you stated that 225-70-17 tires would give you a 0.9" lift, then you changed the narrative..


Good luck.....I'm out...


"Is 2270mm the correct FORSCAN limit for 2025 Hybrids? My factory 225/65-17 shoes are 2273mm circumference.... (also one of the factory model/option combinations have 225/55-19's which has a circumference of 2294mm) I'd like about a 1" lift for my '25 Hybrid XLT, and was considering putting 225/70-17's on which would give me a 0.9" lift, but those have a 2344mm circumference...? Has it been confirmed that Ford engineering specifies a "squish" factor? I haven't hooked up FORSCAN yet to my Mav, but would it show the actual (current) value set from the factory? (Sorry if this was discussed/verified already.)"


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