FORScan Speedo Calibration for larger tires

[petulantskeptic]

This my be a strech, but you think this may be a code that Ford has to show something is not set to the default from the factory?. I had a android that i got into (jailbreak) and it had a code that you could only see when you were in-that mode. I was to show the phone manufacturer that you had been in it. You had to set it back to default before the code would go away. Anyway, just a thought.

No that's not the reason for the code. If you recalibrate the speedometer using Hypertech, it changes the value in that field but does not throw the code because it also changes something else (though I don't know what).

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[forceofnature]

I would like to do this but don't want error codes throwing. My conversion is easy its 10% difference so I can do that in my head.

 

[forceofnature]

well after some internal deliberation, I ordered the OBDLinkEX adapter to use FORscan to fix my speed.

 

[gfitzge2]

I upgraded to the latest Forscan (2.3.27beta). Changed my speedometer calibration to this.


Adjust speedometer for larger tires Changed from 0938 to 0987

BCM - 726-12-01 xxxx ???? xxxx

No codes at all. Now at 70mph my gps shows about three to four tenths of a mph faster than my speedometer. I know that i could tweak it a little more but I think I will just leave it there. It was about 2.3 mph off before the change. Went from 265/65 R17 to 265/70 R17..

 

[jeb134]

I adjusted mine this weekend to compensate for the BFG 285/70R17 KO2's
BCM 726-12-01 xxxx 09E7 xxxx

No codes or warning lights! GPS app and digital speedometer on the dash were pretty close, wasn't able to go too far on a flat surface with cruise control, but when I set it to 50 mph, the GPS app on my phone was showing 49-50 after it had been off by 3-4 mph, so I'm happy with that.

 

[SpaceRanger]

So, I figured I'd recalibrate my speedometer after jumping to 265/70/17's. Yes, I did get the code... But I found this looking through the menus. It was about 100mm's too small on my factory tires (should have read 2433mm). So I changed it to read 2520, closer to my new tire size. I did this before I went through step number 1 to recalibrate my speedometer, took it for a spin, and I can confirm that it didn't do anything. Just figured I'd give you guys a heads up who were wanting to try it out.

 

[BGDOGY]

I put in code 09D2 for my 285/65R18 tires and it works, but it throws the DTC code U0422. Everything else works properly. The speed is actually showing a bit too fast, by 1 MPH depending on what I'm comparing it to. Uniden radar detector is usually identical, but app on phone is 1 MPH slower. Might go download another app and see if there is a difference.

 

[forceofnature]

Did my update finally. I used the code from the spreadsheet then looked at the BCM value for circumference which is off by 90mm. I tried to change to actual mm but it will not take it. So my value is still off slightly but not bad as the speedo and cell phone GPS are within 1 MPH at 60 MPH.

 

[Flapilot]

This Thread is slightly outdated now so I just wanted to update it. Changing the size in the mm selection now does work!

Some fine tuning will still be required. I changed mine to the manufacturers specifications on the tire and instead of being about 5 mph slow on the speedometer I’m about 2 fast. Could be several different issues, how the tire sits on different size rims will effect how tall it is inflated. Other issues too so I’ll keep messing with it until it’s a little closer. I know 2mph isn’t a big deal but small stuff like that bothers me so I’ll tweek it.

 

[Msfitoy]

There're many forscan obd ranging from $20s to nearly $50...which one is recommended and what's the difference between the cheap/expensive ones?

 

[Flapilot]

There're many forscan obd ranging from $20s to nearly $50...which one is recommended and what's the difference between the cheap/expensive ones?

I bought an $18 one. I don’t expect to be using it a ton. It’s worked fine so far.

 

[Msfitoy]

Stock: 255/65-17 - 726-12-01: xxxx 0910 xxxx

Change: 285/70-17 - 726-12-01: xxxx 09DC xxxx

Cruise set at 70mph, GPS reads 70mph. Before the change with the cruise at 70mph the GPS would indicate 75mph.

Anyone else confirm this value to be accurate for this size tire? That's what I get with the calculator but sometimes it's tire dependent. I have Falken AT3W...

 

[Flapilot]

Anyone else confirm this value to be accurate for this size tire? That's what I get with the calculator but sometimes it's tire dependent. I have Falken AT3W...

You don’t have to do that anymore. Forscan has majorly improved their interface. Most of the menus are just drop down and select now.

When you enter the BCM(body control module) and towards the bottom there is a line item “tire size”, its in MM.

Calculate your tire circumstance in MM and insert the value then select “write” at the bottom of the page, and then test with your phone gps. I’ve been using Waze.

The initial value I put in was 2614 which actually over corrected and made my speedometer faster than GPS. I’m currently down 2540 and still a little fast.

based on Faulkens website the 285/70/17 are 32.8” which equates to a circumference of 2617 mm.

 

[Msfitoy]

Newbie question...do I need more than the standard license to make calibration changes?

 

[Flapilot]

Newbie question...do I need more than the standard license to make calibration changes?

No the free one works.

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