Community Forums

Majestic31 · 02-21-2021, 09:29 AM

Just Purchased this truck , Original tires were 20" now has 18" tires, Speedometer now is not correct, in Pensacola Fl. now called Ford dealer was told they can not adjust truck computer without changing gears in transmission . will be travelling back to Phila. soon .

R.Wold · 02-21-2021, 11:03 PM

I did the same thing with my 2017 and got the same response from Ford. So I researched tires and found an 18” tire that had very nearly the same diameter as the 20” lower profile tires that were on it when I bought it. Speedo is now correct. Tires that worked for me are 295/70 18.

I found this tire size calculator very helpful as it allows you to compare tire sizes in every dimension:
https://tiresize.com/comparison/

I lived with the inaccurate speedo for a while racking up more miles on the odo than the truck was traveling until I finally needed tires again. But it was only about 4 mph off so didn’t impact driving.

GBRG07 · 02-25-2021, 11:06 PM

I can't swear to it with a 2013 but I remember changing the tire size in the computer on a few trucks. Was in a area called "Programable Parameters' in the vehicle programming that is accessed through the IDS diag. computer Ford uses. It gave a choice of tire sizes and revolutions per mile choice.
The "programmable parameters" area had things like daytime running lights, police dark modes and stuff like that.

Edd505 · 02-26-2021, 10:06 PM

I have an SCT X4 programmer that allows you to reprogram for different tire sizes. The programmer also changes the ECM & TCM which boosts HP & torque, I use tow mode. It is street legal except CA where everything's illegal and or cause cancer, I'm glad I don't live in there. Guess stuff I use in NM can cause cancer if I cross the boarder.

arcaguy · 02-26-2021, 10:14 PM

You might want to check out Forscan. It's a free download that is supposed to give you all of the functionality of the dealer at no cost except the dongle you need to buy. The one they recommend was about $50. I have done the download but have not used it yet. It may be a pretty steep learning curve but it might be worth it. Good luck.

Here's the link: https://forscan.org/