22.5 to 16.5 MPG!!!!

[G8RB8_12SR5]

The unsprung weight of the tires is what is killing you. I went to stock size Cooper ST Maxx Load E with 2.5" lift and got 14.5 hwy (56lbs per tire I believe). Decided after 1000 miles I didn't care for the hum or the mileage and went to a Cooper AT3s Load C (44lbs a tire vs. stock of 39lbs a tire and discount tire let me swap at no charge). I get 20 on the the highway (where i used to get 21-22) and 18-19 combined vs. 19-20. The lift didn't do nearly and much MPG damage as those tires did and I still have plenty of capability to get me out of any where I've gone with them.

 

[Quentin]

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.

Overstating speed and mpg is legal. ODO is not. Subaru has been sued because of this in the past. I'd say the ODO is correct.

 

[Bourbonator]

I recently put on 275/70/17 Cs on the much lighter konig six-shooters. My math told me I actually lost a few lbs per corner over my stock setup, but I'm sure my rolling resistance is greater now. I'm getting about 1-1.5 mpg less than I was with stock (~18 combined, now). I'm optimistic that I'll see 0.5-1 mpg gain in the spring when we're off winter gas and back in warmer temps.

Just enjoy your truck for what it is - a solidly built, BoF 4x4.

 

[marshal]

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.

how on earth are you getting 13MPG, I'm sitting at almost 4" of lift with a even higher clearance bumper than yours, and 35" E rated tires and i can still manage to get 16mpg

 

[Engineer]

Sounds right, everything starts to add up. I run in the 14-16 range depending on driving. % wise I will admit that is a large drop to swallow but I hope you expected some drop, so the extra 1-2mpg you now have to deal with shouldn't matter. If it does you are in the wrong vehicle.

 

[bloodninja]

how on earth are you getting 13MPG, I'm sitting at almost 4" of lift with a even higher clearance bumper than yours, and 35" E rated tires and i can still manage to get 16mpg

Probably driving around like this

 

[Blue15]

22.5 average? At stock me or the two other 5th gen 4runners in my family ever achieved that number.

I was getting 17.9 new, just around 1st oil change I started 18.5 steady, then lifted 1.75" front with 1" rear spacer it only dropped to 18.3. Stock tires.

 

[BlackWorksInc]

Probably driving around like this

Hey how did you get a video of me off-roading?!

It also depends on a few other factors. For example, for most of this year I've gotten around 13-ish +/- 1mpg-ish on average because I rarely go further than 10~20 miles off driving in a week. The dealership is a mile away and I don't really leave the house for anywhere else beyond taking lunch at work (which is maybe 2~3mi round trip), so the vehicle is hardly warmed up when I am driving most of the week.

Though in the last month or so I've been driving more like 40~60mi per week because I have to regularly go to occupational therapy for my recovering injury and I have been running errands for a bit. My mpg actually went up to about 14~15-ish because of that.

I'm running full RCI steel skids, a 3" OLW 2.5" Dia Lift Kit, Shrockworks Bumper, 33" Nitto's, and a thirsty V8; just to give you an idea.

So realistically they could be seeing a significant drop as a combination of factor including an inaccurate gauge, over all mods, and driving habits.

 

[DesertCanyons]

I recently put on 275/70/17 Cs on the much lighter konig six-shooters. My math told me I actually lost a few lbs per corner over my stock setup, but I'm sure my rolling resistance is greater now. I'm getting about 1-1.5 mpg less than I was with stock (~18 combined, now)...

Just enjoy your truck for what it is - a solidly built, BoF 4x4.

You moved the weight from the rims to the tires, relocating more weight to the outside of the rotating tire/wheel. That increases rotational inertia which slows down acceleration and braking. It takes more power to get the wheels rolling or increase speed.

Two experiments to demonstrate this:
Sit on a single rope swing and start spinning with your arms and legs tucked in. Then extend your arms and legs. You'll see a dramatic decrease in speed of rotation. Pull your arms and legs back in and watch the speed increase again.
Watch an ice skater spinning on the ice. They draw in their arms and legs and start spinning very fast. To come out of the spin they let their arms out and one leg and it slows them down enough to skate forward.

 

[4Rager]

I owned my 14 for almost two years before the lift and daily driving I averaged 18.3mpg in the summer and 17.3mpg with the winter blend gas. They switched to winter gas right around the time installed my lift, and I've now been getting around 16mpg. The highest I ever got was on road trip when the vehicle was completely stock (actually it had a CAI ), and it was just under 22mpg, so unless you drive on the freeway 95% of the time, I find that hard to believe. Then again, if you do drive on the freeway 95% of the time, all of the negative effects other member mentioned will be amplified by the wind resistance, so maybe yours did drop that much.

Here is the math on my last tank. 320 miles on ODO, 19.94 gallons of 87 octane.


265/70r17 Stock Bridgestone 31.6 Dia 99.22 Circ
285/70r17 BFG KO2 32.7 Dia 102.68 Circ

So:

Addt'l inches per rev 3.454
Addt'l % per rev 3.48%

What that means is when the odo thinks I went 300 miles, I actually went 3.48% further than that.

So: 320.6miles x 1.0348 = 331.76 actual miles traveled

331.76 miles ÷ 19.94 gal = 16.14 mpg

Pretty much only 1 mpg less than I got in the winter when the vehicle was stock. One time I wasn't paying attention and accidentally chose 91 oct. I got noticeably more miles on that tank, but not enough to justify the higher price.

 

[Knight-Errant]

22.5 average? At stock me or the two other 5th gen 4runners in my family never achieved that number.

I think he probably means average highway economy, not combined. I get about 22 highway and 19 combined...if this is what he means it is reasonable (I don't dive with a lead foot and my trail is still stock). 22.5 combined though is pretty much impossible unless your commute is downhill both ways.