I have a question for everyone who has lifted their truck or is running bigger tires on their 2015's. How did you re-calibrate your PCM/Speedometer for your bigger tires?

I'm going to install my ICON and 315/70R17 tires soon, and Ford says they can try to recalibrate the PCM for the bigger tire size, but no guarantees. I've also looked into the Hypertech Speedo Recalibration module, but it seems a little pricey for a one time speedo fix and no other features. Tuners seem to be the way to go, but I'm REALLY trying to avoid a tune on a brand new truck (at least until the warranty is out).

Has anyone had any success having a Ford dealer recalibrate the speedo for the bigger tires?

 

Ford dealers can not do it. I work at a Ford dealer in service and have tried to personally. It is not a programmable parameter in IDS anymore on 15 up trucks.

Buy the Hypertech speedometer programmer. It only changes the calibration for the speedometer, nothing else.

 

FWIW- I have a SCT Tuner with 5* tunes and while it is an option to adjust tire revolutions for the speedometer, the program doesn't take. I had to buy the HyperTech.

 

Does re-calibrating with hypertech also fix the park assist? From what I understand it uses the stock tire size to measure distance when parallel parking the truck. I can't use my park assist anymore because it comes way too close to parked vehicles and also rubs the curb due to distances being off from the tire size being out of cal

 

Good question. I don't know the answer. But I think it would depend on what module the hypertech tuner reprograms and what input the park sense system references.

 

Changed from stock 275/55-20 (31.9" Dia.) to 275/65-20 (34.1" Dia.) and also found that the dealership cannot re-calibrate the speedo. It looks like it's off about 4-5 MPH at 65 MPH (Garmin GPS shows 69/70) and my MPG is also off. Revolutions per mile for stock is 632 and the larger tires are 592. It looks like the hypertech is about the only option but at $200 I may just live with it, at least for a while.

 

If you don't recalibrate it not only is your speedometer off your odometer will be as well. I put on 285/65/20 (34.6 inch tires) in and purchased the hypertech speedometer calibrator last week. It's very easy to use but it takes trial and error. You can only choose tire size by inches and in .25 increments. Example 33.00, 33.25, 33.50,33.75 etc. Don't go by your actual tire size. Mine is actually set to 32.75 for a 34.6 inch tire and now dead on by gps. It's only 1/2 of a tenth off on the odometer. Close as I can get it. Very happy with it though. Hope this helps.

 

Do you have the park assist? would you be able to test this for us to see if it corrects the distances when parallel parking?

 

Thanks for all the input, guys. I'm more worried about the odometer being off than the MPH. I guess if Ford can't reprogram for the bigger tires, I'll go with the Hypertech.

Will the Hypertech void any warranties like some other tuners if there is ever an issue? I'm assuming Ford could trace that tune on the PCM just like any other programmer?

 

It shouldnt, but ive wondered the same thing. They could try to say that you altered the programming of the truck. Chances are though, they wouldnt know it was even installed.