What happened to my mileage?
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Joined: Jul 2007
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What happened to my mileage?
YesterdayI put on a single cherry bomb muffler to a duel exhaust, also replaced the stock tires to larger 265/70r/17bf goodrich all terrain tires, now my overhead computer says im getting 12 mpg
and it was 16 before the mods, so is it the tires, muffler or does it maybe need re programed?
and it was 16 before the mods, so is it the tires, muffler or does it maybe need re programed?
Captain
Joined: Jul 2006
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RE: What happened to my mileage?
I had a 1999 Ford Expedition And went to over size tires and did the same for MPG killed it I think I went with 305 - 70 - 16 it was a 32 inch tire from a 30.7 inch tire stock it dose not take much to throw off you'r MPG 17 to 13.
On my Last truck I went from 31 inch stock to a 37.3 inch tire and regeraed it from 3.73 to 4.56 for the tires I went fron 15 to 11 MPG it's the extra Weight and takes more gas to turn them.
On my Last truck I went from 31 inch stock to a 37.3 inch tire and regeraed it from 3.73 to 4.56 for the tires I went fron 15 to 11 MPG it's the extra Weight and takes more gas to turn them.
Administrator
Joined: Jul 2007
Posts: 24,686
Likes: 21
From: South Georgia/East Florida
RE: What happened to my mileage?
The answer is yes, no, yes...
Bigger tires will hurt your mileage some, but your biggest problem is that your computer thinks you're still running stock size tires, your speedo is reading slow and your mileage is showing worse than it actually is.
Re-program...
Bigger tires will hurt your mileage some, but your biggest problem is that your computer thinks you're still running stock size tires, your speedo is reading slow and your mileage is showing worse than it actually is.
Re-program...
Champion
Joined: Jun 2005
Posts: 3,775
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From: Minnesota
RE: What happened to my mileage?
ORIGINAL: HammerZ71
The answer is yes, no, yes...
Bigger tires will hurt your mileage some, but your biggest problem is that your computer thinks you're still running stock size tires, your speedo is reading slow and your mileage is showing worse than it actually is.
Re-program...
The answer is yes, no, yes...
Bigger tires will hurt your mileage some, but your biggest problem is that your computer thinks you're still running stock size tires, your speedo is reading slow and your mileage is showing worse than it actually is.
Re-program...
DC Insider
Joined: Aug 2005
Posts: 2,681
Likes: 1
From: cedar falls, ia
RE: What happened to my mileage?
yeah re-program for sure....if you dont have a programmer then look forward to spendin like $90 at the dealership for em to re-program it....takes all of about 5 min
Veteran
Joined: Jul 2006
Posts: 406
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From:
RE: What happened to my mileage?
All of the above...
And, if you have less than a Hemi, slightly taller tires w/o regearing willprobably have a negative affect on mpg.
And, if you have less than a Hemi, slightly taller tires w/o regearing willprobably have a negative affect on mpg.
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Professional
Joined: Aug 2007
Posts: 230
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From: New Orleans, LA
RE: What happened to my mileage?
Dealership couldn't fix my speedo, had stock 33's on the 20" rims and went to 35"s and dealership told me their computer didn't have a tire size that big and that I'm stuck with the wrong tire size. Do they understand that I'm now running more mileage then what my speedo is recording? Makes my warranty last longer I guess. And I went down to 12mpg too. I've noticed if I'm doing 65mph on the interstate i'm getting about 15-16 mpg. get the truck up to 75 and it drops down to 12mpg. Glad I don't drive too far every day.