Huge MPG drop? Is tire size the problem?

[k9101]

I have a 2012 GMC Z 71. With my truck with stock I was averaging 18 mpg according to the gauge on my truck.

I recently put on a 2 inch leveling kit and put on 275 70 18 BFG tkos. I just checked the gauge on my truck and it's saying I am now getting 12.5 MPG.

Would the small increase in tire size hurt my MPG that much? Or does the MPG gauge need recalibrated for the new tires? Or is it something else I'm missing. Any help is appreciated

[elite0259]

that's what happened to me with my '07(GMT900) silverado... I get 11.5 avg city and 17ish highway if I go ~65 on a flat highway

[66nova]

Multiple players in this game.

 

First the level probably gave you a hit. Second, tire weight probably went up. Third, yes you need to recalibrate your computer. Your truck doesn't think it's going as far as it is when you put a bigger tire on.

[Gmcant33]

To many factors to list but first step should be reset your avg Eco. Then let us know how it works out.

[TooTall1]

Winter blend fuel also causes a big drop in MPG.

[LongrangeLauber]

_{That's a huge drop. Like others have recommended, you need to make sure your computer is calibrated to the correct tire size, and reset your avg fuel economy}

[k9101]

How do I reset/recalibrate my average ECO

[Gmcant33]

How do I reset/recalibrate my average ECO

 

Once your display on the hud is at your avg using the right arrow on ur steering wheel press once and the option of reset will appear press enter by using the check mark in the middle of the four arrows.

[66nova]

Once your display on the hud is at your avg using the right arrow on ur steering wheel press once and the option of reset will appear press enter by using the check mark in the middle of the four arrows.

 

He has a 2012. Not the same process

 

 

Go to your average economy on your DIC. Then push and hold the check mark button until the average goes to 0.0

[chupe442]

Yes, fuel MPG will take a big hit for what you have done...... Resetting your avg will only disappoint you more.. Its averaging the good times prior to mods and the bad times with the mods already.... It all sounds about right though. I am guessing you have 3.42 gears in the front and back as well..

[Gmcant33]

Gears, weight of tires or rims, aerodynamics list goes on and on also driving habits play huge role. So don't be discourage a lift is pleasurable with consequences .

[TooTall1]

Wait until spring....your mileage will actually get better on it's own.

[Zebrafive]

The tire size increase will throw your DIC reading off about 7% since the taller tire is taking you further per revolution. So your 12.5 equates to 13.4

Have you used a GPS to check your speedometer? It will be reading slower than actual.

[k9101]

Yes I've check it and it runs about 3 miles slower thaN real speed. Still reads 12.7mpg after driving a couple days after resetting the meter. Driv mf habits have not changed at all

[becker87]

Same thing happened to me when I put my new tires on, probably a 2-3 mpg drop. O well, it looks better now.