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Large decrease in MPG

fullsendautodetail

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fullsendautodetail New Member

fullsendautodetail

Posted
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So I have a 2018 Silverado 5.3 Z71 LT and I've tried looking up threads for this topic before but for some reason I haven't had any luck.  Ive had this truck for a year now and I had a level lift installed and my MPG stayed around 18-22 MPG and I could get 325-400 miles out of a full tank of fuel.  I recently installed a 3.5 Rough Country suspension lift and I installed 20" wheels with 33" tires.  I knew going into this modification that I would see a slight decrease in MPG but immediately after the install I dropped my MPG to 7.5-9 MPG and I cannot get it to increase AT ALL.  I used to work at a GM dealership and spoke to a couple of old co-workers about this issue and for some reason we cannot pinpoint the issue.  I know that increasing the ride height and the different wheel/tire package would create a difference but I didn't know that it would be this bad.  I'm considering a performance chip and a CAI to try and increase my MPG, and its not a bad batch of gasoline and I've changed my driving habits and kept my foot off the throttle a little bit...if anyone has any info on this it would be greatly appreciated, thanks a lot!!

CombsL83 Enthusiast

CombsL83

Posted
Posted

Wouldn't think you'd drop the much either. What type of 33s do you have? All terrain? Mud terrain? PSI in your new tires could be an issue

Tx_operator87 Enthusiast

Tx_operator87

Posted
Posted

On my 2015 Silverado 5.3 when I leveled it I kept a consistent 17-18mpg, mostly city driving. I had a cai and the diablosport tuner on it, when I put the Toyo open country at2's on it (33x12.5) I didn't recalibrate the speedometer right away and went down to 13-14mpg, hand calc. And when i recalibrated the speedo I was staying around 15-16mpg with consistent hand calculations

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fullsendautodetail New Member

fullsendautodetail

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I have 33” mud terrain tires, granted I live a mile from work and I typically put 15-25 miles a week on the truck so it doesn’t see a lot of highway use. I’m taking a trip this weekend about 3 hours away so I’m goin to use some fuel stabilizer and open it up. I’m not 100% sure what psi to run the tires but they were sent to me with 32 psi..the tires read to run them at 35 psi

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