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Old 07-01-2012, 06:10 PM
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Computer MPG question.

Hey guys, new WK owner here. Just got it about a month ago. I put new tires on it, 275's, and my MPG had decreased according to computer. Now after browsing the forums I've gathered it COULD be due to the fact the computer doesn't recognize the bigger tires and whatnot. Question, is there a way to format it so it does realize that I have slightly bigger tires so I could get a more accurate reading. I went from a '92 Laredo to my '06 so I don't care about MPG, but since this is the first time i've had this technology, i'd like to be able to use it and sorta trust it haha. Thanks for any help.
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Old 07-01-2012, 08:47 PM
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Re: Computer MPG question.

A tuner (like the Superchips) will allow you to recalibrate for different tire sizes.

I've never used one, but many people here have and will be able to point you in the right direction.
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Old 07-02-2012, 11:56 AM
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Re: Computer MPG question.

yep, you will need a tuner
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Old 07-05-2012, 12:23 AM
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Re: Computer MPG question.

Not could be. Is
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Old 07-07-2012, 09:13 AM
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Re: Computer MPG question.

Your MPG is not the only thing that is off because of the bigger tires. Your speedometer is also off. You can get a tuner which will correct those but your MPG will still be lower then it was with the stock tires size.
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Old 07-11-2012, 05:26 PM
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Re: Computer MPG question.

If you don't trust your computers mpg reading do the old fashion math method. BTW correct me if I'm wrong but what does the computer care what size tire you run as it pertains to mpg? Doesn't it measure the fuel consumed reguardless of tire size.
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Old 07-11-2012, 07:53 PM
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Re: Computer MPG question.

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Originally Posted by ACPRO View Post
If you don't trust your computers mpg reading do the old fashion math method. BTW correct me if I'm wrong but what does the computer care what size tire you run as it pertains to mpg? Doesn't it measure the fuel consumed reguardless of tire size.
The size of the tires influences the distance the computer thinks you have travelled. Larger tires = fewer rotations = computer thinking you travelled less distance.

This would also result in the ol' fashioned hand calculations to be wrong as well, if they are based on the Jeep's odometer (which would also be incorrect).
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Old 07-11-2012, 08:04 PM
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Re: Computer MPG question.

So what type of calculations would I do, with the bigger tires. If the odometer is off, is there a percentage I can add to figure out the correct numbers? (Sorry if that didn't make sense, having a hard time wording it haha)
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Old 07-11-2012, 09:20 PM
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Re: Computer MPG question.

Quote:
Originally Posted by Blackout View Post
So what type of calculations would I do, with the bigger tires. If the odometer is off, is there a percentage I can add to figure out the correct numbers? (Sorry if that didn't make sense, having a hard time wording it haha)
google tire size calculator and see far your tires are off from stock and that will show the difference in your speedo. as stated above you cant even do the math by hand because your speedo is wrong as well.
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