600 was pretty close, I am getting 48 mph with cruise set at 50 so I may need to bump it up to 605.

 

@The Brad programmed a guys truck with 40s and landed on 108 for the tone ring and 601 for the rev per miles.

 

Actually, they were 40” tires.

 

So how would you go about figuring out what count you need the tone ring to be if just adjusting the revolutions isn’t enough? I can figure out number of revolutions for the tires size easy enough but is it just trial and error getting the right count and revolutions for a tire large enough that both need adjusted?

 

I guesstimated and started at 115 and made adjustments in 2 tooth increments and compared the speedo to gps until it was accurate.

 

Also in the 7.3L Tech Folder, but we need a thread so others can contribute and correct, right?


FORScan has a pretty robust online forum but very little of the conversation applies to our era of Super Duty, so I figured a write-up covering this topic would be useful. Might also apply to earlier or later models, I dunno.

First you’ll need FORScan and an ELM327 bluetooth scanner/adapter/dongle to communicate with the truck. Scanners are well documented elsewhere so I’ll skip that. FORScan has a few flavors to cover various operating systems, and you can download them here. Also on that page see the link for a comparison of the applications. Currently only the Windows version with an Extended License can execute this service function, but check the links in case other versions gain this functionality in the future. The Extended License is described here and available on the download page mentioned above. Getting FORScan to talk to my adapter proved irksome but troubleshooting that process is beyond the scope of this document. Only tip worth sharing here is go to FORScan settings and select the correct scanner. In my case FORScan sicced onto my phone BT instead of the OBDLink MX I had just paired, so I had to select the OBDLink manually.

You’ll also need the tire RPMs, which is rotations per mile. That is the data we will be changing. This can be had from the tire manufacturers website, or from Tire Rack. FWIW my OE RPM was 649 and I changed it to 637.

Note this simple method only works for tires 35” or smaller, because the ABS module will not accept tire RPM less than 600. Larger tires require changing not only the tire RPM, but also the tone ring count. That is accomplished by this same method (as you’ll see, Tone Ring size is right next to Tire RPM in FORScan) but requires trial and error to get values that work together, plugging in numbers until the speedo matches GPS. Analogous to a 10 speed bicycle with a front and rear gearset. If you find values that work with your tire size, post up the info.

Part of why they hide these features behind the Extended License is because you could screw up important records. No fumble fingers here! Be prepared, take your time, and be careful.

To compliment this write-up and step-by-step below, check out .



Assuming you have all the equipment operational, KOEO, FORScan fired up and connected, and the magic tire RPM scribbled nearby, follow these steps:

1 Open Configuration and Programming, the icon looks like a computer chip. This will display the modules that can be changed. Select the ABS module. The one at the bottom, NOT the AS BUILT version.

2 Down at the bottom of the screen click Run Service Procedure, it looks like a round Play button.

3 In this new tab you’ll see Tire Size (rev/mile) at the top, select it.

4 Back down near the bottom click on the Edit Selected button.

5 Pops open a dialog box; change the value to your tire RPM and click the button with a check mark.

6 The tire RPM will populate in the Tire Size row. Down next to the Edit Selected button is the Write button, give it a click.

7 A dialog box will open. Double check the RPM is correct, and click the check mark button to confirm the change.

8 A progress bar shows the data being written to memory and you’ll hear the ABS module fart under the hood. A dialog opens instructing you to cycle the ignition off, then back on, returning to KOEO. Click OK to close the dialog box.

9 Back to the bottom of the screen click the Stop Service Procedure button. It’s the round button with a square, right next to the Run Service Procedure button.

Done! Bob’s your uncle!

 

I asked @aawlberninf350 to create a thread detailing his instructions and embed the video of how to perform the instructions. This way his advice and video would be in more than one place on the forum.

I have merged the two threads and the posts appear in the order in which they were created.

 

Awesome. Video is good. Both threads have good info. Im glad to see them combined and neither lost!

 

Yes sir!

I think that between the two of you that have provided instructions, there should be zero questions related to the subject. I know for a fact that aawlberninf350 had a crash course in video recording and editing over the past few days. He really put a lot of effort into getting something that people could follow along with in addition to your instructions that are in the first part of the thread.

 

Dude we've been merged! So I can borrow your lawn mower too, right?

 

Don't think this needs a new thread, but I can't seem to find the rev for my tire. Nitto Ridge Grappler 295/75/16. Also I wonder if you can do this from the Forscan app now? I haven't tried it yet, but I already have a ELM27 scanner hooked up to my truck for TP2.

 

I have no clue if the app will do it or not. As for your tires, you should be some where close to 625. Start there and fine tune with a GPS as needed.

 

Ok thanks. Now I just need to figure out how to connect my laptop to my OBD2 scanner. Not using a cable. Not sure if my laptop has bluetooth. Also seems I have to wait for a Forscan approval to get the extended license.

 

If you have a forum account with Forscan all you need to do is go here https://forscan.org/forum/extlic.php

If you are waiting for approval, its probably for the forum access.

If you have bluetooth on the laptop, just pair it with the adapter and you're good to go.

 

If that app works let us know! I still need to do this due to my last tire purchase.