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Has anyone tried to calibrate their speedometer for bigger tires? The hypertech unit does not work on the diesels so it makes me wonder if the forscan change method will work on our trucks?
 

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Nvm I did the change through forscan to try it out and with the new values from the spreadsheet calc I found on f150forum it was dead on with waze gps. So if anyone ever needs help lemme know I can link the stuff needed
 

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I need to do Forscan. What ID did you change? 726-12-01?

Did you have to reset BCM?
 

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That is exactly what I used! Typed in my 295/55r20 and punched in the value it gave me into BCM 726-12-01 and it was dead on with the waze gps on my phone so I am calling her good! I did have to do the PCM and TCM relearn to clear the wrench as well.
 

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@wreedsvt I have used the calculator for you to determine you should change as follows (as a starting point of calibration)...

BdyCM as built
726-12-01
Changed Value = xxxx 0A3B xxxx

See attached screen capture below supporting this...
 

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Thanks! Ill try this later today.
 

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Has anyone tried to calibrate their speedometer for bigger tires? The hypertech unit does not work on the diesels so it makes me wonder if the forscan change method will work on our trucks?
You sure about this?
I found it listed specifically for the diesel on a bunch of sites.
Matter of fact, I was like 30 seconds away from ordering it on 4wp's site.
Did you try the one for the diesel and it not work?
 

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Hypertech makes a unit for the F150 diesel, but it's $229! --> Hypertech

Why hassle with this $229 Hypertech device when you can do it yourself in under 10 minutes with a Windows laptop, a $29.99 Amazon Prime shipped device (https://www.amazon.com/gp/product/B01F0GVBWY/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1), and FORScan software? Also, then you will be set to do all sorts of additional mods to your truck via FORScan.
Yokev,

Not trying to argue with you or anything, but I also agree with kdjasper. We have no idea how Hypertech changes/and what it changes to accomplish the end goal of calibrating the speedo.

We do know however Forscan is writing directly to the BCM, like Ford intended and same as Ford IDS to make the change.

If it were me, save yourself the hassle and just use something that is trusted and works, Forscan.
 

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Well, here is what Hypertech actually states on their product page: "This module is perfect for vehicles with computers that don't allow for tire and gear ratio correction"--see attached screenshot below. We are driving a vehicle that does allow for tire and gear ratio correction via FORScan.

It is perfectly fine if you want to get a Hypertech device to correct for tire size change. Keep in mind that the inline calibrator from Hypertech requires you to disassemble your dash to put the thing in (http://www.hypertech-inc.com/ProductManuals/inlinespeedo/730125_VSS_Instlltn_Prcdr.pdf). A lot more invasive and difficult than using FORScan.

By the way, I am more than double the age of the internet, and I think @wreedsvt is as well, so neither of us are new to the internet, we are just suggesting another and lower cost option of correcting for tire size change. Now you can do what you want with this information, and make your own informed decision on the approach you want to take.

The members of this forum are all very supportive to one another in providing knowledge sharing and assistance, and we understand that people will select different options based on what their personal preference is. For example, with disabling Auto Stop-Start (ASS), some guys prefer to take apart their dash and install an inline unit such as https://www.autostopeliminator.com, others disable via FORScan, and others like wreedsvt disconnect the BMS cable under the hood--all three options disable ASS, but in this case the inline solution still retains the on the fly enablement of ASS in case you're in situational driving where it would be beneficial to have it enabled--so the inline option provides more feature capability over the other two options. In the case of Hypertech vs. FORScan, I am not aware of any benefits the Hypertech unit provides over FORScan and comes with the risk of damaging dash components with the disassembly and reassembly of the dash to perform the install.
@yokev -- report back on how your Hypertech install and configure goes so that others can benefit and learn from your experience--thanks!
 

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@wreedsvt I have used the calculator for you to determine you should change as follows (as a starting point of calibration)...

BdyCM as built
726-12-01
Changed Value = xxxx 0A3B xxxx

See attached screen capture below supporting this...
that value is a little rich, now the speedo is 1MPH high.
 

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@wreedsvt try this setting...

BdyCM as built
726-12-01
Changed Value = xxxx 0A16 xxxx
 

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Yeah I got that value too, I will try tomorrow. I did have to do PCM and TCM relearn to make CEL/wrench go away.
 

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@wreedsvt sounds like you will have it spot on soon. Post results after you have a chance to tweak and validate. Also interested in mpg impact with your larger tires. I'm wondering if the diesels are less impacted on mpg for upsized tires than gassers, so really curious on your report. Thanks!
 

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They are prone to it, I think I am going to lose 1-2MPG. My truck is on fuelly. Need to get speedo right so its count miles accurately though now. I will change values tomorrow, too dark now.

I can already tell MPG is not climbing as quickly to the 20s as it did before.
 

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@yokev -- report back on how your Hypertech install and configure goes so that others can benefit and learn from your experience--thanks!
I was initially a little scared about popping my cluster out, but after watching the instruction video it appeared uber easy. Literally took me 10 mins from tools on floor, to the unit in and tools back on floor.
They have you program it on your computer first(and it also updates itself if need be), where contrary to hand-helds, you simply put in your stock tire size, and your new tire size in the next column.
I hooked up my old Garmin Nuvi after I installed it, and surprisingly it shows it being SPOT on.
Again, with at least my experience with hand-helds, the speedo is never spot on. I've taken the measurements off the manufacture's site and used 'em, and I've also used chalk on the ground to get my tires exact measurement, and I've still been off a couple mph at freeway speed.
What makes the accuracy of this thing more silly, is it just uses the generic measurement for your tire size. Obviously every manufacturer's tires measure out differently, but again, my speedo is spot on, from 25mph up to 80mph-which is where I stopped comparing
 

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@yokev thanks for reporting back that you had good results going the Hypertech route.
 
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