2005 Gmc Sierra Mileage

[svaneld]

I am driving a 2005 GMC Sierra SLE V8. I have 285's with stock wheels on it and it is leveled. I am currently only getting between 12 and 15 miles per gallon in town/freeway. Is this on par with what others are getting? I use no lower that 87 fuel and do not drive with a heavy foot. This has been my dream truck for years and I treat it that way. If it is below can you guys give me some ideas to check on why I am loosing MPG's? My truck has 79k miles on it.

Thanks

[txab]

You're about right. What's the rear gear ratio? Have you adjusted the odo and speedo for tire size?

[jrrod2004]

I am driving a 2005 GMC Sierra SLE V8. I have 285's with stock wheels on it and it is leveled. I am currently only getting between 12 and 15 miles per gallon in town/freeway. Is this on par with what others are getting? I use no lower that 87 fuel and do not drive with a heavy foot. This has been my dream truck for years and I treat it that way. If it is below can you guys give me some ideas to check on why I am loosing MPG's? My truck has 79k miles on it.

Thanks

 

 

my truck: '06 Silverado Crew with 4.8 and 2WD. as of now, I am running high 16 or low 17. took a hit when I put on the new tires and added some fun stuff to the truck (goodies). I used to run 18-19 with the older tires and less weight....

[mxdirtrider56]

Sounds right on target. If you're still concerned, make sure your air filter is clean, change spark plugs, and other tune up items. That mpg range is normal though. My MPGs according to the DIC says I average right around 15mpg.

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I have a 6.0 with 4.10s and run 93(because of tune), I also have 285s, but there street tires. I get about 12-14 MPG and I'm pretty hard on those rear tires.

[svaneld]

Thanks for the reply's. I figured it was close to what it should be but I wanted to see what others thought. I am going to change the plugs out in the next month or so. I have not adjusted the speedo yet. How much does that cost to get it done? Again I appreciate the reply's.

[txab]

Thanks for the reply's. I figured it was close to what it should be but I wanted to see what others thought. I am going to change the plugs out in the next month or so. I have not adjusted the speedo yet. How much does that cost to get it done? Again I appreciate the reply's.

If you haven't corrected for tire size then your MPG readings will be off

[redvett]

Not changing the speedo calibrations hurts fuel economy since the PCM uses the vehicle speed for fuel & timing adjustments and the PCM also needs correct speed for the transmission to shift correctly.