Gas Milage Question

I have a co-worker with a 2013 SR5 running LT275/70R18 tires and what looks like a 2.5 to 3" lift. He says he is only getting about 12 miles per gallon. Is this correct for this? If not, what could be causing such poor mileage.

 

Yes. I’m running a 3.5” all the way around with 33’s and get 12-15mpg

 

Yeah that's not unheard of. Those tires are heavy af, 2 sizes larger than stock and also wider. And it looks like there is a bit of a rear squat going on which is about the worst thing you can do from an aerodynamic standpoint.

 

Which engine does it have?

 

That’s about right…but it’s a truck. If MPG is a huge factor in your decision making, pick a Prius.

 

Welcome to TW...

 

Sounds about right. I've got skinny LT 33s and I get 14-15 no matter how i drive

His aftermarket wheels are probably quite heavy and that topper doesn't help either

 

That cap might not be helping either (I know my Softopper dings mine almost 3 MPG). Also, are you (is he) correcting for the speedometer (odometer) error from those tires?

 

Not sure if he is or not. I also run a soft topper but did not notice a reduction in mileage.

 

I think it's the 6 cylinder.

 

I'm running 285/70/17 on my 08 and I average between 13-15 mpg. Closer now to 15 after replacing spark plugs and using engine cleaner at my oil change.

 

I get 15-17. Have 285s, 3" lift, full armor and bumpers.

But Ive regeared and changed cam gears to help. Same thought process as @RockinU , i didnt get a truck for the mpg..

what was he expecting?

 

I just did a road trip in a Ford F150 and we were getting 22+ MPG. With a much smaller truck my thought it should get better than what it is, after all it is a small truck.

 

I've tracked every tank of gas (except the first) since I bought my 2011 in 2019. Got close to 17mpg with C-load 32" Duractracs, stock gearing, skids, sliders, and a Softopper. Getting around 13 (14.5 corrected w/GPS) with D-load Kenda 35x10.5s, 4.56 gearing, skids, sliders, bumpers, winch, swingout, RTT, bedrack, and tonneau. YMMV.

 

The problem is twofold. (1) the 1GRFE engine is not very efficient for the current era for MPG expectations and (2) the shape of the Tacoma is not aerodynamic for MPG purposes (especially above 70mph).

 

Pretty sure F150s have cylinder deactivation. So you were likely only using 4 cylinders most of that trip.

 

Kind of piggybacking on op's question. I've read on here that when your gas gauge light comes on or you are a bit
below empty there is still 2 or 3 gallons left. When you fill completely up do you have a few gallons above the full mark?
Only asking as I filled up on Sunday drove to and from work 5 days and maybe a few extra miles for errands so about 125 miles for the 5 days.
My gauge only went to the 3/4 tank mark. I recently had my fuel pump replaced so not sure if it's working right or not. I usually just keep between 1/4 - 3/4 tank and
don't fill all the way up often.

 

I always fill up completely, and it typically takes 30 or so miles to drop below the "full" line on the gauge. My gauges shows 3/4, 1/2, and 1/4 full when I've got around 15, 13, and 9 gallons left, and the low fuel lamp usually turns on when there's around 3.5 gallons left.

 

Yep but here are the things that contribute:

• Rotating Mass is your biggest fuel suck because it is constant 0 to infinity and beyond.
• Weight will impact him up to about 45MPH.
• Wind drag after 45MPH becomes significant.

Rotating - So those tires and wheels weigh in at probably around 65lbs each. Stock is probably about 10 to 15lbs lighter. that's 15 less pounds to swing around with every rotation and the larger the wheel is, the further away from center the mass is. If two wheels weigh 10lbs each and one is 31" in Diameter and the other is 35" in Diameter, the 35" tire will take more fuel to spin.

Weight - I see he has a camper on the back. That weighs about 175 to 200lbs. And then what does he have in there? Think there is a conservative 100lbs of "truck guy stuff" in there? Maybe he's carrying 300lbs between the gear and the topper? Pounds and horsepower are directly related. Horsepower and fuel are directly related.

Wind Drag - With that truck up in the air there is more turbulence under it. And lets face it, that's not the most aerodynamic vehicle out there to begin with. Then add on the topper and the added resistance of the tires which are wider and taller. The wind has a lot to bite on to.

Age - That truck probably has 150,000 miles on it? Maybe? Nothing wrong with that! And it will probably do another 150,000 too. But like my knees, everything gets a little looser with age. And that truck was only rated for 20MPG in the beginning.

If everything mentioned above shaved off just 2MPG each, then you are looking right at 12ish MPG.

Purely bar napkin math but yeah. That's about right.
Miles per gallon is usually a story of a death by a thousand paper-cuts.

One thing he can do - make sure that speedometer is calibrated for the larger tires. If not those tires are 9% bigger than stock and will show 9% less MPG than he is actually really getting. That's worth 1.8 MPG and could turn his 12 into a 13.8 which ain't much but it's better than a poke in the eye with a sharp stick for sure.

 

Mine gets 19 mpg's

2" suspension lift, e-rated KO2s

BUT i drive pretty conservative