2021 Ecodiesel - 4" Lift with new Wheels - Gas Mileage Issues

[ib4elk]

I have a 2021 1500 Laramie Ecodiesel and after a lot of research on this forum and others on lifting the ED trucks, I went with the BDS 4" lift (which does require a new drive shaft) and installed new Fuel wheels and Cooper 295/70R18 Discoverer AT3 XLT tires. It was a bit of a cluster in the beginning as the shop that performed the lift didn't check with BDS so the canopy and boxes I have in the back of the pickup was a bit too much weight for the standard 4" rear coils so the back end squatted - had to have 6" rear coils installed. Anyway, it all finally got completed and I am quite happy with the results. The ride is just as good or better than stock and the new tires performed very well in snow and mud this past hunting season.

The biggest issue I am having now is the gas mileage went to crap. I was getting 25-26 MPG with the factory setup and after the lift I am now getting around 19 MPG (a 6 MPG loss). I am not much of a mechanic but wanted to know if anyone else has experienced anything close to this and/or if there is something in the lift kit install that possibly could be torqued too tight to cause this?

 

[ferraiolo1]

You killed your aero dynamics, added more rotating mass/weight, and more road contact area

Mileage drop is normal. But verify your Speedo is correct after the tire change. As that affects the trip computer.


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[BowersFJ]

Dare I ask what kind of decrease you were expecting ?


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[ib4elk]

I had read that many folks were getting 1-2 MPG decreases so that really is all I was expecting. I agree on some weight added and areo dynamic issues but I got better gas mileage while pulling a horse trailer or pulling my camper - both weigh over 3,000lbs. I'm scared to see what it does to my mileage when I attach the trailers... Adding 3-400 pounds should NOT have affected the mileage that much so was quite curious if others were seeing this much of a drop and I just had wrong expectations.

I did get a Tazer DT and used it to fix the speedometer with the larger tires so it is running almost spot on at 75 MPH. I was not using the trip computer to calculate the mileage - would check it after each fill up at the station after I updated the computer with the corrected tire size.

 

[TxRedRebel]

Truck looks great but that sucks about the MPG. I also wouldn't have expected that big of a drop.

 

[jeepin7]

What gear ratio do you have? 3:21 gears on stock tires should have resulted in 27-29 mpg. Going up to a 34.3” tire from 31.9” is big on 3:21 gears pulling the rpm way down.
3:92 gears would be a bit better on the mpg loss, but still a couple points down.


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[NewLove]

I’m looking at putting 285/75r18’s that weigh 10 lbs more a tire on my 2020 Rebel eco and wondering what hit I’ll be taking in MPG.. ?