Speedo is wrong HELP
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Joined: Oct 2006
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Speedo is wrong HELP
I have an 02 F250 PSD that I picked up a couple of months ago and I have noticed that the speedometer is off. I was traveling by a car with a big digital readout and noticed that he was doing 65 while my truck said I was doing 70. Later that day I went thru one of those small towns that has a portable speed sign that shows you your speed. I had it sitting on 60 but the sign said 56. I have the original size tire on the truck and it's not jacked up or anything. Could someone have tuned it for bigger tires and not changed it back when original size tires were put back on? I can live with it but it would be nice for it to be accurate. Thanks.
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Elder User
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If it's like the older PSD's, you can reprogram it yourself free. Should be able to be done 6 times.
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Laughing Gas
Joined: Apr 2005
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From: West-Central New York
I just purchased larger tires and two different dealerships told me nothing could be done. How do I recalibrate it myself or how can they do it?
I need to know fairly quickly because I have a trip I'm going on and I need to charge for mileage.
I need to know fairly quickly because I have a trip I'm going on and I need to charge for mileage.
Laughing Gas
Joined: Apr 2005
Posts: 910
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From: West-Central New York
I put on 255/85/r16. It was the best I could find for a taller but still narrow tire using the stock dually rim with no spacer. I'm still getting a 1/4" spacer because they're just too close when loaded for me to feel comfortable.
They are 3 inches taller and my speedo is abit slow right now.
After doing a search on this forum I called my multiple dealerships and reprimanded three of them for not knowing they could do that even though they're a certified ford technician. The fourth one set me an appointment for next friday, which was their earliest opening.
I am just wondering if their was a way to do it myself as someone suggested.
They are 3 inches taller and my speedo is abit slow right now.
After doing a search on this forum I called my multiple dealerships and reprimanded three of them for not knowing they could do that even though they're a certified ford technician. The fourth one set me an appointment for next friday, which was their earliest opening.
I am just wondering if their was a way to do it myself as someone suggested.
Postmaster
Joined: Jan 2005
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From: Peoria, IL
That's only about a 33" tall tire, so the dealer shouldn't have any problem doing it. As far as I know the only ways to change the tire size on a super duty is through the dealer, with a programmer/flash device, or by adding on a unit such as the Superlift Truspeed (which is about the only thing you can do if you have 35"+ tires).
I believe on the old body style trucks there was a way to change the tire size yourself, but I am pretty sure there isn't a way on the Super Duty.
I believe on the old body style trucks there was a way to change the tire size yourself, but I am pretty sure there isn't a way on the Super Duty.
Senior User
Joined: Nov 2006
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From: Southern California
I think its a setting in the PCM, which can usually be corrected IF you have a tuner... if not, then its time to visit ford... but then again, the $60 you would spend at Ford could go towards buying that tuner 
Joey
Joey
Senior User
Joined: Nov 2006
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From: Southern California
Beerstalker, anything with a VSS can only have the speedo corrected by the ways you mentioned... in the old days, you could change the speedo gear on the tranny or t-case to one with a different number of teeting, depending on the size of tire you got... not anymore... it gets it from the VSS on the rear axle...
Joey
Joey
Laughing Gas
Joined: Apr 2005
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From: West-Central New York
Thanks, Beerstalker, for the quick reply.
That was my general conclusion after reading all the speedometer threads.
I was simply holding out for that miracle, do-it-myself cure. I just wanted it fixed to track my mileage on a trip to Ohio and back starting Monday morning. I know, I could figure out the correct mileage by Googling it but that's just not the same as pushing that little button in the dash.
That was my general conclusion after reading all the speedometer threads.
I was simply holding out for that miracle, do-it-myself cure. I just wanted it fixed to track my mileage on a trip to Ohio and back starting Monday morning. I know, I could figure out the correct mileage by Googling it but that's just not the same as pushing that little button in the dash.