F150 Tire Size Correction Speedometer Inaccurate

Post here with any questions you have regarding theuse of the i2 on supported Ford applications.

Moderator: sohfast94

Post Reply
nsbohn
Posts: 2
Joined: Sun Jul 14, 2019 9:50 am

F150 Tire Size Correction Speedometer Inaccurate

Post by nsbohn »

I have a 2016 F-150 Supercrew 4x4 XLT with a 2.7L EcoBoost.

Per my window sticker, the truck has a 3.55 Regular Rear Axle and came factory with 275/65R18 Goodyear Wranglers A/T's.

I installed a 2.5" leveling kit, and mounted 285/75R18 Falken Wild Peak A/T3W's. They look great on the truck, but threw the speedometer off by a pretty solid margin. The speedometer would read about 65 when doing 70 per GPS.

After setting up my tire size in the Intune i3, I'm reading about 2-3 mph higher than actual speed. Put another way, when I set the cruise control in the truck to 70 mph, the GPS reads 72-73 mph.

Per the manufacturer's website, the Falken's turn at 599 revs per mile. more info here: https://www.falkentire.com/tires/light- ... a/t3w-tire
The goodyear's were 651 revs per mile. https://www.goodyear.com/en-US/tires/wr ... izes-specs

Is there something wrong in the calculation in my i3? Can I manually change the revs per mile to get this corrected?
User avatar
mikel
Posts: 57766
Joined: Tue Jan 16, 2007 1:17 pm
Location: DiabloSport World Headquarters
Contact:

Re: F150 Tire Size Correction Speedometer Inaccurate

Post by mikel »

adjust the aspect ration value or use height in inches to get the speedo where you need it.
Mike Litsch
DiabloSport Brand Manager
Diablo Tech support by phone:
561-908-0040
M-F 8:00 AM to 5:00 PM EST

tech@diablosport.com
User avatar
Mike_Levy
Posts: 6727
Joined: Fri Oct 26, 2007 8:11 pm
Location: Between Orlando and Tampa

Re: F150 Tire Size Correction Speedometer Inaccurate

Post by Mike_Levy »

I have the same problem with the Lightning. Even when it’s supposed to be corrected, it’s still 5-6mph off. No idea if it’s because of the tires or rear end though, because both have been changed.
2021 BMW M550i xDrive
BMC Drop ins, JB4

2010 Nissan Murano beater
K&N Drop-in
User avatar
mikel
Posts: 57766
Joined: Tue Jan 16, 2007 1:17 pm
Location: DiabloSport World Headquarters
Contact:

Re: F150 Tire Size Correction Speedometer Inaccurate

Post by mikel »

Mike_Levy wrote:I have the same problem with the Lightning. Even when it’s supposed to be corrected, it’s still 5-6mph off. No idea if it’s because of the tires or rear end though, because both have been changed.
does it change at all?
Mike Litsch
DiabloSport Brand Manager
Diablo Tech support by phone:
561-908-0040
M-F 8:00 AM to 5:00 PM EST

tech@diablosport.com
User avatar
Mike_Levy
Posts: 6727
Joined: Fri Oct 26, 2007 8:11 pm
Location: Between Orlando and Tampa

Re: F150 Tire Size Correction Speedometer Inaccurate

Post by Mike_Levy »

mikel wrote:
Mike_Levy wrote:I have the same problem with the Lightning. Even when it’s supposed to be corrected, it’s still 5-6mph off. No idea if it’s because of the tires or rear end though, because both have been changed.
does it change at all?
It seems to have changed some, but not much. I went from 3.55 to 4.10 though, so if it wasn’t changing at all it would be much further off.
2021 BMW M550i xDrive
BMC Drop ins, JB4

2010 Nissan Murano beater
K&N Drop-in
User avatar
mikel
Posts: 57766
Joined: Tue Jan 16, 2007 1:17 pm
Location: DiabloSport World Headquarters
Contact:

Re: F150 Tire Size Correction Speedometer Inaccurate

Post by mikel »

well, hard to say here.
Its just math, so if it changed at all it should have changed to the correct value. Never heard of a similar issue on a Lightning, but you seem to have the possessed Lightning :)
Mike Litsch
DiabloSport Brand Manager
Diablo Tech support by phone:
561-908-0040
M-F 8:00 AM to 5:00 PM EST

tech@diablosport.com
User avatar
Mike_Levy
Posts: 6727
Joined: Fri Oct 26, 2007 8:11 pm
Location: Between Orlando and Tampa

Re: F150 Tire Size Correction Speedometer Inaccurate

Post by Mike_Levy »

Kinda what it seems like, doesn't it? :twisted:
2021 BMW M550i xDrive
BMC Drop ins, JB4

2010 Nissan Murano beater
K&N Drop-in
Juice
Posts: 37
Joined: Thu Oct 20, 2016 7:03 am

Re: F150 Tire Size Correction Speedometer Inaccurate

Post by Juice »

On my 2008 e350, I was unable to correct speedo for larger tires. I2020 would flash my adjustment to pcm but not affect the speedometer at all.
Post Reply