22.5 to 16.5 MPG!!!!

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Bino9905

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I have 33k miles on 2013 4x4 sr5

I added bilsteins all the way around......top setting up front and 1.5 spacer in rear

Kept stock wheels and went with 285 BFG AT tires

At 70 MPH my average mpg dropped that much.....i was expecting 2 or 3 max

Is it the tires or lift that is the major culprit?

Now wish I had gotten stock size and went with original style BFG AT and not these new k2
 
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those aren't your actual numbers. The different tire size is not calibrated with the on board MPG calculator. The only way to accurately measure your MPGs is with a pen and paper from now on
 
There is no free ride. Setting higher in the air allows more airflow under the 4runner. This is why NASCAR teams want that front splitter as low to the ground as allowed. Taller heavier tires just kill mpg. I doubt you were getting 22.5 mpg consistently before, maybe once or twice on an ideal situation day. I doubt the old style bfg gets better mileage than the new KO2. I do notice in Arizona with 75 mph speed limits my mileage drops fast over driving 55-65 mph. A headwind, hills and higher speeds really kill mpg. Also with the 285 you are actually going more miles than the odometer shows from the taller diameter. Best to check speed and miles with a gps
 
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It varies depending on actual tire dimensions, but a generic 285-70R-15 is about 3.5% bigger than a generic 265-70R-15. So you are running about 3.5% faster than you were before, but the computer thinks you are going the same. This means that instead of 70 you are going 72-73mph.

Wind resistance is a function of the square of velocity, so it's actually a 12.25% increase in wind resistance. That is a 3mpg drop based purely on the increased speed. So you can get part of your mpg loss back by driving with your speedometer back at about 67mph... or use a GPS to set your speed at an actual 70mph.

Add to that a small drop for additional rolling resistance for the AT tread. And add a pretty good drop for increased wind resistance from the lift... more air is now flowing through the undercarriage which has a much higher wind resistance than the top (and that air is flowing at 73mph instead of 70mph).

So part of your mpg drop is user error (you are driving faster than you were before), part is from computer error (the computer thinks you aren't traveling as far as you really are per gallon of gas burned), and part is from added wind resistance from the lift and rolling resistance from the tires.

As [MENTION=128102]littlezavasaurus[/MENTION] said, you need a calculator and detailed notes to get your actual mpg.
 
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Bino9905 said:
I have 33k miles on 2013 4x4 sr5

I added bilsteins all the way around......top setting up front and 1.5 spacer in rear

Kept stock wheels and went with 285 BFG AT tires

At 70 MPH my average mpg dropped that much.....i was expecting 2 or 3 max

Is it the tires or lift that is the major culprit?

Now wish I had gotten stock size and went with original style BFG AT and not these new k2
Click to expand...

I guess you did not read this first...
http://www.toyota-4runner.org/5th-gen-t4rs/208403-changing-tire-size-wheels-read-first.html

Most of it is the tires. More rolling resistance and quite a bit more unsprung rotational mass (probably about 80+ lbs). The lift also has impact at higher speeds.

Anyway, like others said. The calc is different now... It's actually probably more accurate. I found mine was pretty much right on for a 33" class tire. It was over stating ODO and mpg and speed with a stock tire size. Sort of a cheat from the factory. So if it makes you feel any better you were probably under 20 before ;-)

And fuel is also changing this time of year... More ethanol... Then there is driving in a strong wind... Like other said, got to pay to play.... Maybe buy a Jeep on 35s LOL

Actually, one thing I have thought would be cool... Would be a road air dam that you could quickly pull off and throw up on the roof rack... It would look goofy as hell but would be very functional for MPG gains on the hwy. Aftermarket bumpers are another big drop in mpg at hwy speeds. I've learned to to be very happy with 16-17mpg when I can get it. I avg 15 but have seen as low as 12.
 
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Bino9905 said:
I have 33k miles on 2013 4x4 sr5

I added bilsteins all the way around......top setting up front and 1.5 spacer in rear

Kept stock wheels and went with 285 BFG AT tires

At 70 MPH my average mpg dropped that much.....i was expecting 2 or 3 max

Is it the tires or lift that is the major culprit?

Now wish I had gotten stock size and went with original style BFG AT and not these new k2
Click to expand...

.........:ybrick:
 
Nelson_ha_ha!.png
 
Bino9905 said:
I have 33k miles on 2013 4x4 sr5

I added bilsteins all the way around......top setting up front and 1.5 spacer in rear

Kept stock wheels and went with 285 BFG AT tires

At 70 MPH my average mpg dropped that much.....i was expecting 2 or 3 max

Is it the tires or lift that is the major culprit?

Now wish I had gotten stock size and went with original style BFG AT and not these new k2
Click to expand...
That sounds about right, mine dropped further, down to 13mpg with ARB bumper. But, I didn't buy it for the mileage, and I really love how it crawls over rocks and tears over desert roads. Interestingly, re-gearing to 4.56 didn't hurt mileage but added low end power.
 
22.5 average? At stock me or the two other 5th gen 4runners in my family never achieved that number.
 
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i had the same issue, dropped to 17mpg so I ripped out the 5100s and tires and bought eibach lowering springs and low profiles. Now I am getting about 32mpg:rockon:
 
wfo9 said:
Actually, one thing I have thought would be cool... Would be a road air dam that you could quickly pull off and throw up on the roof rack... It would look goofy as hell but would be very functional for MPG gains on the hwy.
Click to expand...
I've had the exact same thought. I lost about 2mpg after a lift, AT tires (stock size), and removing the front air dam (not intentionally... it kept hitting things and tearing so eventually I just finished tearing it off).

I've pondered how to make a solidly-secured but easily-removable air dam work.
 
Currently have a 4wd f150. I leveled it and did not change tires or wheels. The higher stance dropped my mpgs by 2mpg. When i added taller and heavier (not wider) tired I lost another 1-2mpgs. Our vehicles come from the factory fined tuned to get as many mpgs as possible within reasonable efforts or dollars. Basically I agree with pretty much everything that has been said here

Bino9905 said:
I have 33k miles on 2013 4x4 sr5

I added bilsteins all the way around......top setting up front and 1.5 spacer in rear

Kept stock wheels and went with 285 BFG AT tires

At 70 MPH my average mpg dropped that much.....i was expecting 2 or 3 max

Is it the tires or lift that is the major culprit?

Now wish I had gotten stock size and went with original style BFG AT and not these new k2
Click to expand...
 
I've been trying for some time to figure out a solution to this problem - the best thing I've come up with is to buy a set of these for the front:
coilover.jpg

and lower springs out back with airbags, or full bags in the rear. Then you could probably drop the height down to -1-2" for street duty and pick it back up offroad. Like the current LC200 or GX460 does, but without the weird hydraulic shock system they use.

I've also wondered if the rear couldn't be done with a set of Fox air shocks along with light weight coil springs. (I know fox wants you to use nitrogen for pressure, but they'll work just fine with regular air for this type of application)

Unfortunately I already have fox 2.5 remote reservoir coilovers, so it's a tough pill to swallow removing them for a smaller 2" king shock. But, alas I have not found any source for an air bag that will fit a 2.5" shock body. I can sort out the coils spring easy enough.

Combine that with a flip down air dam on some small actuators (like the 3000gt's used) and you could have an active aero mode that would probably return at least a few mpg, maybe 3-4?? The front suspension is the real deal killer so far for me.
 
My suspension is stock.

Best mileage ever - took the oldest kiddo from Chicago to Bloomington, IL on 6/29/2015, and used the fill-up and odometer method. Got 23.75.

On the way back I took country roads, cuz its funner, will at least until I got sort of lost on the south side, got 23.39.

The odometer could be lying, the gas pump could be lying.

Going to put up with stock tires until after the September 2016 trip to Indiana.
 
I used to pretty easily get 18mpg, with stock wheels and tires. I 'upgraded' to PTR20-35110-BK w/BFG KO2 275/70r17 and now my mpg immediately dropped to about 16.5 and the wheels are about 1-2 lbs lighter than the stock ones were. I'm Using iphone app to calculate mileage, not the onboard display.
 
Increase mileage with skid plates

wfo9 said:
I guess you did not read this first...
http://www.toyota-4runner.org/5th-gen-t4rs/208403-changing-tire-size-wheels-read-first.html

Most of it is the tires. ... The lift also has impact at higher speeds.
... Would be a road air dam that you could quickly pull off and throw up on the roof rack... It would look goofy as hell but would be very functional for MPG gains on the hwy. ...
Click to expand...

I thought that's what 300# of skid plates was for, to smooth out the undercarriage for increased gas mileage. :zoom:
 
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