I just bought a set of 17" wheels & tires off of a 2003 Expedition and will soon be swapping out my stock 235/70/17's and wheels for the new 265/70/17 that I bought. The height is different and therefore my speedo will be off. I know there is no speedo gear but how does the dealer compensate for wheel changes? Is it in the ECU or is there relacement part that I need to buy to get my speedo back?

Also... I am in need of a set of center caps for these wheels. Anybody got some they want to sell?

Russ Rogers

 

If you find the answer to this let me know. According to my dealer, they are at a loss for how to calibrate these new speedos. I went from the 17's to 20's and my speedo is off as well. I contacted a speedo calibration shop here in the Houston area, and he said, "bring it in and I'll tinker with it".

Yeah right

Hey Dusty...anything in your shop manual about this?

 

just don't mix... Hopefully some of the sharp minds on the site will have something to offer us...

Later,
Russ Rogers
Ft Worth TX

 

ford has a computer made especially for them that plugs in to every ford and you can re-calibrate your computer fot the correct revolutions per mile it can also shut annoying things off loke the seat belt minder auto locks without going through the procedure yourself

 

I know my hypertech computer for my GMC would adjust for tire size and much more. Any word on them putting one out for the 04 f150?

 

I just posted something like that on another site asking kind of the same thing. I want to ditch my 17 inch wheels and put a set of the 18 inch FX4 wheels on mine and was kind of wondering how much work the speedo will be.

 

Here is link that someone posted earlier that shows the effect on the speedometer of changing wheel and tire sizes.

http://www.csgnetwork.com/speedocalibcalc.html

 

Thanks brown...that one is much easier to read the results than the one I have been posting to people. I like how you can also enter different speeds. Very helpfull indeed

 

Word. That web site is great. Thanks

 

I was guessing that going from 18's to 20's changed my indicated speed by about 5 mph at 70, but this confirms it. Let me know if anyone finds a way to recalibrate...

 

This topic keep scoming up and Hypertech is happy because it gives them one more excuse to sell their gadgets. Fact is: The manufacturers are required by law to calibrate their speedo so it accommodates different tire and wheel sizes within a specific precentage range. You do not need to recalibrate your speedo for this. The result would be that it has the same level of accuracy as it has right now, plus or minus x%

Some people will spend money on anything...

 

Can you explain.

 

Mmmmhh...I thought I did.
Forget about the legalities.
Look at rus_rog 's example. He went from 235 to 265 on 17. It translates to a variation for the speedometer from 70mph to 73mph, that's between 3% to 4%. Standard variance on speedometers is probably at a conservative 5% if not more (that is 5% either way, +/-).

Exactly what do people think they are calibrating?