Hi all, I have 35's on my 00 Ex. The speedo is off by about 4 or so mph. When it reads 55, I'm really going about 60-61. I know some programmers can correct for tire size, but do you have to use and install a programmer to correct for tire size? Is there another option? Thanks.

 

I am not sure about the 2000 models, but the newer Fords have a 600 tire revolution per mile limitation. The OEM 20" tire & rim combination from the 2005+ years clocks in at about 34.1" in height, and they have a TRPM of 609....which means that 34" tires are about the tallest tire you can correct by simply reprogramming the PCM (and ABS module). Although, in this case, it could get you pretty close...even if you did just get a TRPM of 600 programmed. Any dealership can make this change. They will likely charge you 30-60 minutes at shop labor rates.

Incidentally, you can get the TRPM for your tires from the manufacturer's website, or a third party site like www.tirerack.com.

Beyond a simple reprogramming, you would have to look at something along the lines of Superlift's TruSpeed. http://www.superlift.com/accessories/truspeed.asp

 

I got the TRPM on my tires, gave that information to my local Ford dealer and had them calibrate it for me, forgot how much it cost but it was less than $50.

 

Real Easy One. Buy a WAAS enabled GPS

 

I'll be getting a 5.5 lift by Superlift and new 16" wheels, so when I have it installed, I'll get the TRPM and then have the dealer re-calibrate it.
This also crossed my mind.

 

You can also use a TRUE SPEED from superlift to adjust the speed sensor signal faster or slower for different tire sizes.

 

Ok, I'll look into that. Thanks for all the suggestions.

 

Do a search for "Programer just for changing tire size and correcting speedo". I used a TrueSpeed from Superlift and like it. I got some pics in myy gallery. I would check with the dealer to see if it is within his bounds to correct but if not check on a TrueSpeed or tuner.

 

the dealer should be able to do it for you

 

I went from 2.65 x 17 to 2.85 x 17, and the two local Ford dealers said that size is out of Ford's range so they cannot re-calibrate the speedo. The max is what they sell, and in my case, 2.75 x 17. They also said by using a SuperChip or equivalent will void the warranty. I have 20K miles now on my 2006 F250, and they hinted I should wait until 36K when it's out of warranty before I use a SuperChip. The speedo difference is not much, I just hope I'm not hurting the engine in any way.

 

you're not hurting the engine in any way

my f250 with a hd 5spd has a mechanical odometer in it which will not allow a programmer to correct it. does anyone know if there is a way to correct my speedo for the 37's i put on it?

 

Your dealer is feeding you a line of BS. You need to find a reputable dealer with a qualified 6.0 tech and have them reprogram the PCM for the different tire rev/mile.

The PCM can be calibrated to accept up to a 35-inch tire or 601 revs/mile.

2006 SRW SD OEM tire sizes:
265/70R17E (31.8x10.7x17) 654 rev/mile
275/65R18E (32x11x18) 649 rev/mile
275/70R18E (33.1x11x18) 626 rev/mile
275/65R20E (34.1x11x20) 609 rev/mile

You installed 285/70R1 (32.7x11x17) 636 rev/mile.

A Truspeed would work but you do not need to spend the money for this as the PCM can be reprogrammed.

 

Hmm unless you have a special truck that has a different part because it was a government truck, the VSS is generated by a tone ring on the ring gear in the rear axle and therefore a Truspeed will work to correct your speedometer & odometer.
www.superlift.com/accessories/truspeed.asp

 

actually, it was a government truck.i was actually looking at the dakota digital thing that seems to do the same thing and is cheaper.

http://dakotadigital.com/index.cfm/p...rod/prd126.htm

dakota digital does make high quality stuff and they do have great tech support.

 

What exactly is a "qualified 6.0 tech"? Is that a Ford qualification for a Ford technician? Is that what I'd ask for when I call the service department?
Thanks.