Gas Milage
02-01-2011, 06:26 PM
#12
JK Freak
Join Date: Dec 2010
Location: Mandeville, LA
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Remember that if you don't have the computer (odometer) flashed for bigger tires you lose MPG as the Jeep reads one revolution as a shorter distance than it actually is.
Look for "tire size MPG calculator" online. I lost 8% mileage in the switch from stock to 31's.
Either the dealer can do the flash or get a Superchips to make the adjustment.
Look for "tire size MPG calculator" online. I lost 8% mileage in the switch from stock to 31's.
Either the dealer can do the flash or get a Superchips to make the adjustment.
02-01-2011, 07:06 PM
#13
JK Enthusiast
Join Date: Oct 2010
Location: Lugoff, SC
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Remember that if you don't have the computer (odometer) flashed for bigger tires you lose MPG as the Jeep reads one revolution as a shorter distance than it actually is.
Look for "tire size MPG calculator" online. I lost 8% mileage in the switch from stock to 31's.
Either the dealer can do the flash or get a Superchips to make the adjustment.
Look for "tire size MPG calculator" online. I lost 8% mileage in the switch from stock to 31's.
Either the dealer can do the flash or get a Superchips to make the adjustment.
02-01-2011, 07:26 PM
#14
JK Enthusiast
Join Date: Sep 2010
Location: San Luis Obispo, CA
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2 door x with 3.5 inches and 33s. My speedometer and opometer are not calibrated but according to them im getting 11mpg
I hope that im getting more like 15
I hope that im getting more like 15
02-02-2011, 06:51 PM
#15
JK Freak
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Not sure about your X, but mine came with a 255/70/17 which is a 31" tire. Also saying 8% doesn't mean jack truly, that could be a wide range depending on what you got prior to your tire swap. Considering what you should get, would be a little easier to say you lost about 1.5 MPG.
The point is that you need to account for the difference in tire size in your hand calculations. If you don't - your calculation will show a loss of mileage that is not accurate. The weight of the larger tires will cause actual loss in MPG, but the increase in size without the adjustment will show a loss in MPG's greater than the actual loss because the odometer is not calibrated for the larger tire. You can adjust by recalibrating the computer (flashing) or add the % difference (in my case 8% or about 1.5 mpg).
02-04-2011, 08:50 AM
#19
JK Newbie
Join Date: Jul 2010
Location: Chicago, Illinois
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I have 35" KM2's with a 3:73 gear ratio. In a week or so I'll be re-gearing to a 5:13 setup. I have an Auto tranny as well. In the City I get about 11 MPG and 15 MPG on the highway. I will post my findings with the re-gearing.
02-04-2011, 05:03 PM
#20
JK Newbie
Join Date: Jan 2011
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I am running 35s on stock gears with a manual getting about 13.5 round town...aweful. My 4.88s just arrived so in a month I'll give you the latest on the improvement I am hoping for