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Discussion Starter · #1 ·
So my speedo has been off because of tire change and DIC showed around 13.5 on mpg. Yes did it by hand also and it was in a couple of tenths. Changed gears to a 430 and reprogrammed to 410 (did not have 430 in programmer) and mpg showed 14 ish and speedo was off 7mph. Yesterday programmed it to 456 speedo was right on and showed 16 Mpg. So with all that info what I am really wanting to know is if odometer runs off same thing as the speedo. Cant calculate it by hand if it is wrong also..... Damn near confused myself typing that.
 

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use 4.10 setting but also use a smaller tire diameter...should get u close to ur actual speed. Don't worry about the mpg on DIC, get the speedo right and hand calculate it. I had to do that with my ranger since the hand held didn't have my gear/tire combo
 

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Mmm Sandwich
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It is all run off the speed sensor. however the dic does not use the odometer to make its calculations. It uses fuel consumption based on speed and stored tire height. Generally if your speedo is correct manually doing it will be the most accurate
 

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Discussion Starter · #4 ·
It is all run off the speed sensor. however the dic does not use the odometer to make its calculations. It uses fuel consumption based on speed and stored tire height. Generally if your speedo is correct manually doing it will be the most accurate
So your saying if the speedo is correct then the Odometer is correct?
 

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Discussion Starter · #6 ·
use 4.10 setting but also use a smaller tire diameter...should get u close to ur actual speed. Don't worry about the mpg on DIC, get the speedo right and hand calculate it. I had to do that with my ranger since the hand held didn't have my gear/tire combo
When I changed it to 456 the speedo was right on. It was 7 off when using 410. That was both with correct tire size.
 

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Mmm Sandwich
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Did you put in the actual height of the tire or 35 or 33. It will take some work to get it exact. But if the speedo is correct it's fine
 

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When I changed it to 456 the speedo was right on. It was 7 off when using 410. That was both with correct tire size.
idk how that's possible :think:

was the speedo right on at all speeds or just one speed where u checked at? How are u confirming speed?
 

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Did you put in the actual height of the tire or 35 or 33. It will take some work to get it exact. But if the speedo is correct it's fine
this....u need the roll out of the tire, then divide it by 3.1416...that will give u ur actual tire diameter. I use a thick blob of white out, drive fwd a bit so u get the blob on the ground...add some more white out to the tire and drive fwd again to get another dot on the ground...measure the distance between the 2 white dots, that's ur roll out.
 

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Discussion Starter · #11 ·
this....u need the roll out of the tire, then divide it by 3.1416...that will give u ur actual tire diameter. I use a thick blob of white out, drive fwd a bit so u get the blob on the ground...add some more white out to the tire and drive fwd again to get another dot on the ground...measure the distance between the 2 white dots, that's ur roll out.
I have a tire roll out gauge I will use and see what it is. As of know I have just been putting in 35.
 

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Mmm Sandwich
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I have a tire roll out gauge I will use and see what it is. As of know I have just been putting in 35.
That is your problem. What is your turner asking for height of tire or the circumference? Most ask for height. Most 35s are not 35" tall. Get a tape measure and measure the height. The tuner should do the math for ya
 

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Discussion Starter · #13 ·
That is your problem. What is your turner asking for height of tire or the circumference? Most ask for height. Most 35s are not 35" tall. Get a tape measure and measure the height. The tuner should do the math for ya
It ask for tire height
 

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Mmm Sandwich
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Then you need to measure the actual height of your tire but that won't work since you don't have a matching gear in the tuner. Like Eddie said did you check your speedo and mutiple speeds
 

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Discussion Starter · #15 ·
Then you need to measure the actual height of your tire but that won't work since you don't have a matching gear in the tuner. Like Eddie said did you check your speedo and mutiple speeds
Yes it was right on from 5 to 75.
 

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Discussion Starter · #16 ·
The major thing I was wondering is if the odometer would be wrong also. Dont really want to be putting more miles on the truck then what it has. And would be nice to be able to hand calculate mpg.
 
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