2015 SR5 Fuel Efficiency Questions?

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thomasj1107

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I am just curious to know how long the "break in" period would be and how long fuel efficiency would continue to increase and why?

I have changed out the stock wheels to TRD wheels and the stock tires to BFG KO2 275/70/17. How much will that effect fuel efficiency on highway and city and how long of a break in should I expect, if any.

Thank you for all the help, I am not overly concerned with MPG or I wouldn't have been buying a 4R, I am just very new to the 4R family and curious about what to expect.
 
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bloodninja said:
Where did you hear of a break-in period for fuel efficiency?
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It's pretty common for most vehicles. Combination of polishing and work hardening bearing and bushing surfaces reduces friction. I think it's a lot of very small friction reductions that add up to just a little bit of improvement. Even tires will have some break in period as the rubber breaks down and rolling resistance goes down lightly. For an easy example when you set the preload on wheel bearings if you drive for a bit they'll register a lower preload measurement.

In my 4runner I've measured slight increasing mileage over time that settled in around 10k miles.
 
my 2014 came up at the 20K mark...went from about 17mpg to now a solid combined 18.4-18.7mph.

i was able to squeeze 22mph highway on my latest road trip to Ct...i am currently at 35K on my clocks...


if that helps you any.
 
Jetboy said:
It's pretty common for most vehicles. Combination of polishing and work hardening bearing and bushing surfaces reduces friction. I think it's a lot of very small friction reductions that add up to just a little bit of improvement. Even tires will have some break in period as the rubber breaks down and rolling resistance goes down lightly. For an easy example when you set the preload on wheel bearings if you drive for a bit they'll register a lower preload measurement.

In my 4runner I've measured slight increasing mileage over time that settled in around 10k miles.
Click to expand...


Thanks for the reply! Are you running stock tires, if not, how much did the change effect fuel efficiency?
 
mnofpeace said:
my 2014 came up at the 20K mark...went from about 17mpg to now a solid combined 18.4-18.7mph.

i was able to squeeze 22mph highway on my latest road trip to Ct...i am currently at 35K on my clocks...


if that helps you any.
Click to expand...

It sure does, thanks! Are you running the stock wheels and tires? Any other aftermarket upgrades?
 
Stock 15 SR5 2WD, stock tires
Average 18.8 MPG @ average speed of 81mph highway

1600 on the clock

town/mixed <70mph speed 17.9mpg 2500 on the clock
 
2015 SR5 just hit the 3500mile mark, been getting 17-17.5 mpg the entire time, has stock 265/75 Goodyear Duractracs that I put on at the 80mile mark.
 
thomasj1107 said:
Thanks for the reply! Are you running stock tires, if not, how much did the change effect fuel efficiency?
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Until last week I was on stock size goodyear ats. My lifetime average was 19.4. I noticed an improvement in my daily commute over time. I've done about 4k highway miles so the average is different from my daily routine by a little bit. I just swapped to 285 Toyo AT2s. Haven't even been through a full tank yet. So far the computer is saying about 17.8 this tank. It'll take a bit to get a good average.

I live close to work - so the mileage isn't a huge deal for me. My weekly commute is about 50 miles, so I might buy gas once a month if I don't go anywhere far away during the weekends.
 
thomasj1107 said:
How does a suspension lift effect the fuel efficiency, if at all?
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A lift and those tires (BFgoodrich K02 275/70/17) will lower your fuel economy. Those tires are E Load which means they are 10 ply, have a stiffer sidewall and are quite a bit heavier then stock. By installing these your are adding more rotational weigh causing your vehicle to work harder. When I installed my lift and tires (the same tires you have) I lost about 3 MPG. I also have a 4th gen but I am sure the change is MPG will be similar.
 
thomasj1107 said:
How does a suspension lift effect the fuel efficiency, if at all?
Click to expand...

The tires are the first and biggest hit. The rolling resistance is significantly higher on most larger tires. You'll likely lose 2mpg with stock size E rated tires vs a p-metric. So if you can - keeping light weight low resistance tires in a larger size can go a long way.

Most people do a "leveling" lift that puts the front higher. This changes the aerodynamics of the vehicle. It's designed nose down for a reason. Part of that is to keep as much air flow over the top as possible. The bottom isn't very smooth and has a lot of turbulence. The less wind resistance down there the better. A splitter/air dam could probably net back at least 1mpg. Maybe more. As would side skirts and smooth wheels. Air height adjustable vehicles do have significant fuel economy benefits by dropping down closer to the road.

Finally you also have the mathematical issue with error in your miles traveled. Taller tires travel further for the same recorded distance. So even if you were equally efficient, it would seem like you lost a little mpg.
 
Jetboy said:
The tires are the first and biggest hit. The rolling resistance is significantly higher on most larger tires. You'll likely lose 2mpg with stock size E rated tires vs a p-metric. So if you can - keeping light weight low resistance tires in a larger size can go a long way.

Most people do a "leveling" lift that puts the front higher. This changes the aerodynamics of the vehicle. It's designed nose down for a reason. Part of that is to keep as much air flow over the top as possible. The bottom isn't very smooth and has a lot of turbulence. The less wind resistance down there the better. A splitter/air dam could probably net back at least 1mpg. Maybe more. As would side skirts and smooth wheels. Air height adjustable vehicles do have significant fuel economy benefits by dropping down closer to the road.

Finally you also have the mathematical issue with error in your miles traveled. Taller tires travel further for the same recorded distance. So even if you were equally efficient, it would seem like you lost a little mpg.
Click to expand...

Is there a P rated tire that will still perform decently well for off road situations? Nothing crazy, but hunting, fishing, wildlife management area hunting/camping, weekend trail riding situations?

I understand the miscalculation, but how much would it be off... if for example I have the larger tires and the computer calculates 18 mpg, is it more like 19, or not even that much?
 
I have p rated at3's in 285/70/17. And they have performed great. My vehicle is used for hunting and we have some nasty red clay roads around here. Some sliding but even the big mudders slide in this junk. Havnt had any problems getting where I need to go, just have to apply the skinny pedal and clean em out lol
 
There are a handful of p rated tires in that size. Toyo at2 and Nitto tg2 are a couple. C rated lt tires would also be more appropriate. Most "floatation" sizes are c rated. Sizes like 33x12.50x17. Most tires come in a variety of sidewalls but this size is kinda slim because most ats going on f dude trucks.


On the other end of the spectrum I have bias ply tires for more hardcore stuff on my landcruiser. They are horrible on the road. But they are very tough sidewalls. And I couldn't get radials to last very long so I moved to bias ply.
 
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