Calibrating Speedometer
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Senior User
Joined: Oct 2007
Posts: 112
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Calibrating Speedometer
Anybody ever recalibrated their speedometer after adding larger tires? Dealership told they were unable to do this on my 08 SD. I went to 37x12.50x20 and I think I'm about 8mph off.
Cargo Master
Joined: May 2002
Posts: 3,271
Likes: 229
From: Gulf Coast, FL
Ask your dealership if they are able to reprogram the ABS for the new tire size. Use your tire manfacturer's tire revs per mile or if limited by Ford programming use the lowest it will go.
Posting Guru
Joined: Jan 2006
Posts: 1,513
Likes: 1
The dealer should be able to do this no problem. Consider that a truck with 17's (32" tire) and a truck with 20's (34" tire) have the same PCM in them. Its just a matter of setting the revs per mile which is readily available. I have had this done before - not on my 08 yet - but it shouldnt be any different than any other vehicle I have had done. Most programmers have this function as well if you are going that route.
P.S. Nice truck!!
P.S. Nice truck!!
Postmaster
Joined: Jan 2005
Posts: 4,743
Likes: 3
From: Peoria, IL
He has 37" tires, so his revolutions per mile number would be lower than the dealer can set it, so they can't do it (unless maybe Ford changed the limit for the 08+ trucks).
He will most likely have to get something like the SuperLift Tru-Speed.
He will most likely have to get something like the SuperLift Tru-Speed.
Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
The ABS module can be programmed for larger than 35" tires. But the limiting factor is the dealer software to re-calibrate. That's why they told you they couldn't do it, the are limited by their equipment at the dealership. It will only accept as low as 601 revs per mile, which equates about to a 35" tire.
Autoenginuity can now reprogram for the 7.3L trucks up to a 40" tire, and the ABS module will accept it. I'm not sure when they will have that available for 6.0L and 6.4L trucks.
Autoenginuity can now reprogram for the 7.3L trucks up to a 40" tire, and the ABS module will accept it. I'm not sure when they will have that available for 6.0L and 6.4L trucks.
Junior User
Joined: Jan 2004
Posts: 51
Likes: 0
From: Jerseyville, IL
The ABS module can be programmed for larger than 35" tires. But the limiting factor is the dealer software to re-calibrate. That's why they told you they couldn't do it, the are limited by their equipment at the dealership. It will only accept as low as 601 revs per mile, which equates about to a 35" tire.
Autoenginuity can now reprogram for the 7.3L trucks up to a 40" tire, and the ABS module will accept it. I'm not sure when they will have that available for 6.0L and 6.4L trucks.
Autoenginuity can now reprogram for the 7.3L trucks up to a 40" tire, and the ABS module will accept it. I'm not sure when they will have that available for 6.0L and 6.4L trucks.
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Junior User
Joined: Jan 2004
Posts: 51
Likes: 0
From: Jerseyville, IL
Now that I have had a chance to play with it, it was well worth the money. The software allows me to change tire size in quarter inch increments which is nice. My tires spec'd out at 34.88 so I just used 35.00 as my tire size which means my vehicle speed is slower than indicated. The list of vehicles in the Ford enhanced version includes the 6.4L diesel.
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