SPEEDOMETER CORRECT HELP

07F350_6.0

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So Ive been searching for so many different ways to get my speedometer to read correctly. Searched to no success on other sites. My 07 Lariat came with factory 275/65/20. Im not running 33x12.5x20. My speedometer is off by 4 to 5 mph. Ive tried using my SCT Livewire to adjust with the CORRECT RPM. But doesnt work, which Ive read up happens alot. Ive used the IDS to try and change it as I work at a Ford Dealership. DOesnt work. Are there any aftermarket devices designed for adjusting the speedometer? Thanks. If this has been brought up before I apologize ahead of time :toast:
 

6.0 Tech

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So Ive been searching for so many different ways to get my speedometer to read correctly. Searched to no success on other sites. My 07 Lariat came with factory 275/65/20. Im not running 33x12.5x20. My speedometer is off by 4 to 5 mph. Ive tried using my SCT Livewire to adjust with the CORRECT RPM. But doesnt work, which Ive read up happens alot. Ive used the IDS to try and change it as I work at a Ford Dealership. DOesnt work. Are there any aftermarket devices designed for adjusting the speedometer? Thanks. If this has been brought up before I apologize ahead of time :toast:
You can use the ids, if it doesnt let you put the tire size in, figure out which rear end ratio and tire size to get it right. What size tires are you running now?

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07F350_6.0

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You can use the ids, if it doesnt let you put the tire size in, figure out which rear end ratio and tire size to get it right. What size tires are you running now?

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Ive tried IDS. I figured out the closest RPM combo to what I have and it didnt work
 

6.0 Tech

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Ive tried IDS. I figured out the closest RPM combo to what I have and it didnt work
Ok, didnt know if you had tried screwing with the rear end ratio as well or not. I know pro comp, hyper tech, and some others make plug in deals that should fix it. Personally I dont like them as its anothe pos to **** up, but when they work, they seem to work fairly well.

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07F350_6.0

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Yea i didnt mess with the gear ratio. Just entered a tire size that theoretically shouldve corrected my issue. I may mess around with it again. What pro comp/hyper techs are you taking about??
 

HossDieselWorks

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I used the Inline #730111. Simple to use, download the program from Hypertech, select your vehicle, original tire size and new. Burn it to the unit, plug and play. Takes all of maybe 15 minutes to do.
 

HossDieselWorks

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And no, because its a signal interrupter it will not affect any tuning/programmers you may have. I run it with my custom tunes on my SCT and havent had any issues whatsoever.
 

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