MPG affected that much by tires?

[Brian3676]

My 08 used to get 17-18 (real life MPG, the on board thing read 20-21) for 50/50 city/highway. I would get 19-20 highway. I put some 1" bigger BFG Ko2 on my truck, the heavy 10ply ones. I now seem to get around 14mpg(real life MPG) and the on board thing reads about 15.

Should 10ply tires really kill MPG that much or should I start looking into something else causing this. (By the way, no frozen brake calipers since I know thats common) This is a 50/50 city/highway driving, but even last weekend driving to the beach all highway no traffic I only managed 15.

They have been on for about 3 months now, so I can confidently say its accurate data and not just complaining about 1 tank of gas.

 

[Velonici]

You would be surprised at how much a small amount of weight can change the vehicle when its spinning. While I know changing size can make a big difference but I wouldn't be surprised if the weight plays a bigger part.

 

[V4Ind]

Thats about what my 6 banger is getting with my current size tires. 15mpg on a good day, I also commute around 40 miles one way all highway as I live and work right off the highway. But the on-board computer says I get 17-18mpg. That don't match me common-core math though!

 

[Drunner97]

When I put the grabbers on the Tacoma I lost about 2mpg with the heavier tire compared to stock but those were Es. Duratracs I just put on are bigger than the grabbers, but they're the SL and lighter so we'll see what it does on my commute this week.

 

[Davy180]

That sounds about right, what size tires are you running and are you a V8 or V6?

I put on a lift and 275/70/15 BFGoodrich KO2's Load E on in April and I am getting around 15mpg mostly city. I have a V6 and am pretty light on the throttle also. Keep in mind each of your tires are probably at least 20lbs heavier then stock.

 

[ARK_SWAMP_RIDER]

Won't help a lot, but when you upsize tires the odometer will read slow, so you go further on a tank then it shows. I suggest using a GPS to verify mileage and calculate based on that.

 

[m85476585]

Make sure they are inflated correctly. LT tires need about 12 PSI more than what is specified on the door jamb sticker.
http://www.toyota-4runner.org/engin...s/110299-lt-tires-need-more-air-pressure.html

More rotational weight shouldn't matter much for cruising at a constant speed. It has more of an effect for acceleration.

Larger tires mean you are really covering slightly more distance than the odometer thinks, so you should correct for that in your calculations. For example, if you went from 30" diameter to 31" diameter you should multiply your measured MPG by 1.033. You are also driving slightly faster for the same speedometer reading, so slow down a bit. And you effectively made the gearing slightly taller, so the transmission might have to downshift slightly more often to compensate for what it thinks is increased load.

 

[fullboogie]

You're also affecting your gear ratio, which is affecting acceleration (in addition to the increased rotational weight, which is the worst kind to add).

 

[ebg18t]

Why do people even worry about MPG? Gas is designed to be combusted and the remminant gasses expelled out the exhaust tip. Lower MPG usually correlates to more fun.

 

[m85476585]

Why do people even worry about MPG? Gas is designed to be combusted and the remminant gasses expelled out the exhaust tip. Lower MPG usually correlates to more fun.

- Because having long range on a tank is really convenient. (On one road trip I spent less on gas in a 4runner than a small car I was travelling with because they had to fill up in the middle of nowhere. I did the entire trip on exactly one tank.) External gas cans are kind of inconvenient.
- One vehicle that gets lower MPG than another might be more fun, but for a given vehicle if you do stuff that lowers the MPG, like adding weight or drag, you are also giving up performance because the engine can typically only put out so much power.
- Because more MPG = more money to spend on gas, so more long trips. Or more money to spend on upgrades. If you have unlimited money, then that's great! Could you send me some?
- It's kind of like a game. Who can get the highest score?
- A sudden drop in MPG could indicate a problem that needs attention, like a dragging brake.
- Some of us like hiking, biking, camping, and enjoying nature. We might need 4runners to get there, but we might as well have as little impact as possible so others can enjoy those things too. For an extreme example, see How Jeeps Reclaimed Iceland, And How Diesel Soot Is Taking It Away

 

[CXS]

To the OP, yes. Tires can make a big difference.

Some of us like hiking, biking, camping, and enjoying nature. We might need 4runners to get there, but we might as well have as little impact as possible so others can enjoy those things too.

Are you insinuating that those of us who get low mpg's don't like hiking, biking, camping, and enjoying nature? Seems pretty narrow-minded. This is a 4Runner forum not a tree hugger forum.

These mpg threads pop up regularly and always make me wonder if the buyer had any idea what he was buying. As a reminder take a look at what the EPA estimates (always higher than reality) are.

 

[Drunner97]

^ +1 If I cared about mpg right now, I would have bought a car instead of a 4runner after my motorcycle accident. I needed a back seat for my son, and I wanted something fun that the two of us could enjoy together.

When I can't afford it, I'll sell the Tacoma and buy another motorcycle.

 

[ebg18t]

- Because having long range on a tank is really convenient. (On one road trip I spent less on gas in a 4runner than a small car I was travelling with because they had to fill up in the middle of nowhere. I did the entire trip on exactly one tank.) External gas cans are kind of inconvenient.
- One vehicle that gets lower MPG than another might be more fun, but for a given vehicle if you do stuff that lowers the MPG, like adding weight or drag, you are also giving up performance because the engine can typically only put out so much power.
- Because more MPG = more money to spend on gas, so more long trips. Or more money to spend on upgrades. If you have unlimited money, then that's great! Could you send me some?
- It's kind of like a game. Who can get the highest score?
- A sudden drop in MPG could indicate a problem that needs attention, like a dragging brake.
- Some of us like hiking, biking, camping, and enjoying nature. We might need 4runners to get there, but we might as well have as little impact as possible so others can enjoy those things too. For an extreme example, see How Jeeps Reclaimed Iceland, And How Diesel Soot Is Taking It Away

Lol.

 

[Sungod]

I went about an inch taller and 2 inches wider in tire size. The E load range increased the tire weight about 7lbs. Somehow even with the 3% adjustment for speedometer error, I went from 17mpg to 15mpg. I was pretty shocked to see an increase of about 40lbs total and an extra half inch of radius increase would have such an impact. Who knows, maybe the 8 inches of extra width cause more drag as well? I guess it was the sum of the changes and not one particular change that killed my mileage, but 2 mpgs is big hit.

 

[m85476585]

Are you insinuating that those of us who get low mpg's don't like hiking, biking, camping, and enjoying nature? Seems pretty narrow-minded. This is a 4Runner forum not a tree hugger forum.

My point is it's harder or less fun to do that stuff in a Prius, so we drive 4runners. But minimizing impact on the environment is a reason to want to get more MPG out of a 4runner. Everyone has different priorities for a vehicle, and obviously MPG is not the top consideration for any of us. Space, capability, and comfort are more important.

The 4th gen (newer V6 models, at least) probably got the highest MPG out of similarly capable vehicles of the same age. For example, see this comparison:
https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=23831&id=23827&id=23812&id=23788

The Xterra and Wrangler are both smaller than the 4runner, but they get lower mileage. The Explorer is probably a bit bigger (it had a third row, but it was useless for adults. I think newer models have more space there), and it gets much lower mileage.

 

[wadle5]

https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=23831&id=23827&id=23812&id=23788

The Xterra and Wrangler are both smaller than the 4runner, but they get lower mileage. The Explorer is probably a bit bigger (it had a third row, but it was useless for adults. I think newer models have more space there), and it gets much lower mileage.

And the Runner has the largest gas tank too! But lets all be honest, the ford is a joke :barf:

 

[yosh2000]

i lost about 1.2-1.5 mpg when i went from 265/65/17 street tires to my 265/75/16 duratracs.

 

[nevada]

My 08 used to get 17-18 (real life MPG, the on board thing read 20-21) for 50/50 city/highway. I would get 19-20 highway. I put some 1" bigger BFG Ko2 on my truck, the heavy 10ply ones. I now seem to get around 14mpg(real life MPG) and the on board thing reads about 15.

Should 10ply tires really kill MPG that much or should I start looking into something else causing this. (By the way, no frozen brake calipers since I know thats common) This is a 50/50 city/highway driving, but even last weekend driving to the beach all highway no traffic I only managed 15.

They have been on for about 3 months now, so I can confidently say its accurate data and not just complaining about 1 tank of gas.

as said above, taller tires means you are going faster/further than what the speedo/odo is reporting. so unless you are accounting for that difference, you calculation is off.
also, the 10ply isn't really an issue, just make sure to run them at the correct pressure. technically, they should have slightly less rolling resistance, that should theoretically, make up for the extra weight..

I went about an inch taller and 2 inches wider in tire size. The E load range increased the tire weight about 7lbs. Somehow even with the 3% adjustment for speedometer error, I went from 17mpg to 15mpg. I was pretty shocked to see an increase of about 40lbs total and an extra half inch of radius increase would have such an impact. Who knows, maybe the 8 inches of extra width cause more drag as well? I guess it was the sum of the changes and not one particular change that killed my mileage, but 2 mpgs is big hit.

I expect you already know this, but yes the extra resistance from the width is having a large effect on the mileage. you could try bumping up the pressure slightly, to see if that helps.

 

[Angstrom]

On my old 3 gen, I switched to BFG AT (all terrain) tires which cost me about 4 MPG. But they made up for it on traction. I hardly ever used 4WD after that. I have Michelins on my current 4th gen V8 and get about the same mileage as the smaller older V6.

 

[Brian3676]

I have the V8. I am not complaining about MPG to be a tree hugger. I am far from what. I suspected a 1-2mpg drop. Just not as big as I seem to have gotten. Anyway, thanks for all the replies, I guess it would appear my truck is likely fine.