Does speedometer accuracy affect anything in the trucks computer other than the Speedometer Reading? Other things like MPG and that sort of thing. I mean I can deal with knowing I'm 72 when speedometer says 70, but don't want other things out of whack.

 

I have no clue. Not something I get overly concerned about I guess. When I was on a recent trip, my speedometer was matched with my GPS unit. My guess would be, and it's just a guess, that the digital information on speed that is gathered by sensors on the truck, is what is used in calculations for other information. It would have to be.

 

It controls the park assist as well. I don't use my park assist with the 35" tires I have on because it throws out the distances the computer thinks the truck as traveling and makes you come very close if not hit other vehicles and the curb when parallel parking.

 

Again.. Shame on Ford for putting smallish tires on their truck and disallowing electronic calibration. Not sure what they solved. They should just us enter our tire size ourselves.

 

Of course it does. Anything tied to the rotation of the tire will be off. MPH, MPG, DTE, ... How could they not be affected?

If you could change it, you could set it so that it showed the lowest possible mileage on the odometer, falsely raising the value when you sold or traded it.

 

Makes sense ...but at least let the dealer change it.

 

I checked my speedometer before the new tires and it was bang on. After the tires not so much. It was about 8% off but a speedo calibrator took care of that.

 

What effect does installing 35" tires, in place of 32", have on the odometer? (wink)

You would think Ford would be interested in keeping odometers accurate by allowing the dealer to adjust the computer's tire size to match what is actually on the truck.

 

I guess they figure if you're going aftermarket then go aftermarket, including speedo calibration.

 

You'll have to find someone to do it for you. Ford says they cannot re-calibrate the newer trucks.