Tire Size and Speedometer Recalibration

[mainrotor]

I recently put 265/75-16 Goodyear Duratracs on my 2000 Explorer Sport. The stock size was 255/70-16, so I have speedometer error now. I found a couple posts on this forum by ExplorerDMB from several years ago addressing how to get a Ford dealer to reprogram the revolutions per mile parameter in the ABS system to correct the speedometer error and printed the pertinent parts of ExplorerDMB's posts and took them along to the Ford dealer this past Friday with the correct revs/mile number (657) for my size Duratracs. The tech that I spoke to in the service department seemed to have no problem following the logic of reprogramming the ABS to correct speedo error for tire size. The price was quite reasonable at $51.94 and I picked up the vehicle a little later in the day. Problem is the programming didn't "take". When I used a stopwatch and mile makers on the highway, repeated timings at 60MPH show the exact same error I had (approximately 2.5-3.0mph) before the programming. It goes back to the dealer on Monday for another try.
Can anyone tell me if there are any tricks or pitfalls to making this programming change that the tech at the Ford service department might not be aware of. It seems simple enough to me, but there must be something going on that didn't let the proper change happen in the computer. Just looking for help to get a good result from the dealer. Thanks in advance for any help.
Mainrotor

 

[flamingX]

I ran into a simular problem when I regeared the rearend on my F-150. I ended up just buying a SCT tuner and did it myself. For some reason it still reverts back to stock setting, so I plug in the tuner, hit 'return to stock' than reinstall the tune.

 

[RobSwindol]

I have an SCT tuner on my 2000 mountaineer. I tried to get James @ Henson Performance to recalibrate it for my new tires, but he said it wasn't possible on my model. What are my options?

 

[flamingX]

I have an SCT tuner on my 2000 mountaineer. I tried to get James @ Henson Performance to recalibrate it for my new tires, but he said it wasn't possible on my model. What are my options?

When you plug in your SCT, depending on the model, while setting up the type of tune you are installing there should be a menu to change gear ratio and tire "Rotations Per Mile" You will need to calculate that (there are many websites that offer it, can't think any off the top of my head, google will give you tons)

My SCT is the X3 pre-loaded and everything was as simple as punching a few buttons. If yours isn't pre-loaded you may have to set it up through SCT's web site first. Speedo calibration is all part of any tune.

 

[Mrhobby100]

what about those speedo sensor calibrators jet chip makes one and also truspeed. Plugs into the speed sensor tone ring plug. I am looking into one. I run 32's and my speedo is way off.

 

[Bronco2]

I use the ford racing calibrator tool for a Mustang.. Just hook up power and cut and solder the signal from and to into blackbox...
Then set the setting switches and it runs great now...

 

[turboexplorer]

I run the truespeed one and its been great so far. I had to for my 37's Post #470 in my build thread.