Bought my son a 2003 F150 Supercrew FX4. It had a 2" lift on it when we bought it but it had the factory wheels and tire size on it.

We swapped those out with some 16" wheels and some 285/75R16 Nitto Terra Grapplers.

The speedometer was off before we put the new tires on it so I figured the truck must have had bigger tires on it at one time.

Speedometer reads 60 but on my GPS you are going 67. At 20 you are doing 22. So it is roughly 10% off.

Anyways I take the truck up to the local Ford dealer to have them calibrate the speedometer. They hook it up to the laptop and do the calibration. I pick it up and while driving home I notice that it is still 7 mph off. I take it back and they said there is nothing they can do to get it closer.

Here is what my ticket says...........
Does anyone know a way to get the speedomter to read more accurate than 10% off?

My son will be 16 tomorrow and I would love to have this issues fixed so he isn't always second guessing his speed.

Thanks!

 

The dealers are limited to what their software will recognize and do. The only way I know is to buy a handheld tuner that allows you to adjust it yourself. SCT makes a good one for that year and you can get it at 5 Star Tuning.

 

I thought I read that the dealership could calibrate up to a 35" tire. The tires that we put on it are 32.76" in diameter.

I really don't want to spend a couple hundred on a programmer just to calibrate unless that is my only option.

 

I have no idea what their limits are, just know that others have run into the situation where the dealer had a specific list of tires they could adjust for and if your size was not on that list, they could not do anything. The only option was changing the tires or getting a programmer to get it corrected.

 

That is your only option if the dealer can't get it any closer.

When properly calibrated, the speedo will say about 62 when you are doing 60, this is by design.

 

The dealer I went to is in a very small town and he even said he isn't sure if their machine is up to date.

I was hoping that a technician at a larger dealership would chime in and let me know if maybe a different dealership could do it.

Guess I will start looking for a used programmer. Or just pick him up a GPS unit.

 

It was a mistake to take to the dealer and have them do that now when you get a tuner witch is the only way to fix it, Takes for ever to figure out what tire size setting to put in because the dealer changed something else that throws the whole deal off..

 

they can adjust it on newer truck at the dealer. NOT on 98-03's they can set it for the largest stock tire size. that is all. Like I said once they do that it screws the programer up when you go to adjust for your gear tire combo it way off. I did it..