Speedometer recalibration with IID Tool

DaytonaRS7

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interesting.
I didnt need to go that large when i changed my wheel information so i didnt know there was a limitation

some one else needs to chime in now.
 

Jimmy Brooks

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Odd. Assuming you have the same tires as me, can I see your settings for the IID tool in the instrument pack menu regarding tire size so maybe I can spot if there’s something entered in wrong?

interesting.
I didnt need to go that large when i changed my wheel information so i didnt know there was a limitation

some one else needs to chime in now.
 

DaytonaRS7

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Odd. Assuming you have the same tires as me, can I see your settings for the IID tool in the instrument pack menu regarding tire size so maybe I can spot if there’s something entered in wrong?
my tire size is 255/60/19. but i can post pictures tomorrow for comparison anyway.
 

Jimmy Brooks

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Did a freeway run after adjusting the rolling radius, still at 60 MPH gps says 64. Need more suggestions.


Anyone played with speed scale factor? Could this have something to do with it?

7CA7D14B-0F83-439C-9E31-171217CA455A.jpeg
 
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avslash

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It might be that speed factor that I am thinking of. Whatever it was, I do remember it incremented in small, whole numbers (1,2,3,4) etc. IIRC, I dropped it down to an entry of 1.

Wish I could be more help, but it has been years since I did it and as I mentioned, I can't log in to the truck to check right now.

If the speed factor doesn't do it for you, shoot me an IM and I will check when I get my IID back in hand next month.
 

HarryO

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I fitted BFG KO2 265/65/18s and was worried about the Speedo initially. Checked it against a GPS and another vehicle (up to 120kmh) and it was almost spot on. The asked a friendly policeman neighbor to check me with dis radar gun at 60kmh and 80kmh and he said it was within the tolerance that he would normally allow.

Been driving for 2 years and no speeding fines.

Guess LR factory speedo settings read slightly under.
 

TrinidadLR4

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If someone could tell me how to address this too, I'd be grateful. Currently running 275 55 20s, and at an indicated 75mph, i'm doing 81mph according to GPS, which puts me in reckless driving territory in the great state of VA. Since the limit in question is 70, this is an issue.
 

Jimmy Brooks

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Well I raised the tire size MSB IPC to 33 and found out it was more off, reading even slower, so just to experiment I lowered it down to 30 and boom it was spot on. Apparently lowering the size of the tire on tire size MSB IPC makes your speedometer read faster.... even though making the tire size smaller should make it slower...... I don’t understand it, this car never ceases to amaze me. I’m just glad it’s over and I don’t have to worry about it anymore. I’ll send a screenshot of my settings tomorrow so anyone else with 265/65R18 can copy it down and calibrate theirs.
 

TrinidadLR4

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That's awesome - please post if you can. I can recreate what you did with my 275 55 20 size and be close, if not spot on.
 

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