MileageTerrible Milage bone stock with new tires

My '11 DC LB 4x4 is bone stock with 265 75 16 cooper courser axt tires. I was getting pretty good milage driving like a normal person, 70mph on highway and average 18mpg.

I know about winter gas, I know larger more aggressive tires will drag more, rotate less throwing all the mpg calcs off. But will all of these factors make me lose 2,3, even 4mpg?

 

If you have more than say 10-15k I'd switch the diff oil out to synthetic and see if that helps. It made a big difference in my truck.

 

Have had Michelin Ltx Ms2's (p245/75-16) on my 09 Access Cab PreRunner about 2 months replacing Dunlops. Between old ones almost worn out, winter gas, and the fact that the Ms2's are .4 inch wider in tread, lost about 1.5 mpg - this is after recalibrating ScanGauge and several tanks of gas.

Much better tire, particularly on wet pavement and unpaved roads.

 

Are you calculating for the tire size difference? You may only be 1-2 lower.


Or something else may be wrong.

 

Yah I don't know how to compensate for the tire size difference from before to know. I know that would give a false loss.

The diff oil is a good suggestion thanks.

 

What kind of number difference did you see?

 

will a morre agressive tread make much difference? Same size tires

 

It's about 3.7%, try the tire size calculator.

http://www.tacomaworld.com/forum/tirecalc.php

 

Either way, I don't really think 18 mpg is terrible mileage. Maybe if you are getting 15 mpg or so I'd be worried, but 18 is right around average.

 

He WAS getting 18, which he said was pretty good in the OP.

Now he is down a few.

 

OP, 15mpg x 1.037 = 15.555
16mpg x 1.037 = 16.592

So, whatever you're getting, it's still not that much higher with the tire size difference compensation.

I don't know if 3.7% is correct btw, I simply took it from the post above.
When I went from 265/70s to 265/75s on my Taco I'm pretty sure the difference was 3.4%

My tires now are 11.9% off, so I multiply my mileage by 1.119. So now you know how to correct it

 

Yes. Very easily.

I at one time was getting 13mpg in my modified Tacoma.

 

Yah I was getting a pretty steady 18. This morning I filled up and got 14.8mpg.

 

I average about 16 mpg but I do very little freeway driving. If I wanted a gas miser I wouldn't have bought a truck. Yes, it's a little disconcerting that my Tacoma gets the same gas mileage I was getting in my Tahoe but to put it into perspective my '08 Accord 4 cyl was only averaging around 18 mpg.

As others have suggested check your tire air pressure and you could change your fluids to synthetic but when it is all said and done the tire size will be a factor in your fuel mileage decrease.

 

While I appreciate the input, I think you're missing the point, at least with the first part of your post.

I'm not bitching about my milage so much as I'm concerned in a sudden decrease with only a tire purchase.

Going up a size should have only been a 3.7% decrease due to calculations. And since I didn't go from a car tire to a Micky Thompson MT I don't see a large loss coming from tread aggressiveness IMO.

I like my truck, I'm just trying to diagnose a potential issue, that's why I calculate my milage with Fuelly with nearly every tank.

 

that is curious. i wouldnt expect a 3 mpg penalty from the step up in tire size.

but i do have the michelins, and they are some excellent MPG tire..for me.

 

heavier tires will decrease mpg

bigger diameter tires will increase mpg [unless they go wider then it's a crapshoot...]

smaller diameter will reduce mpg most of the time

depending on those factors combined....skews mpg
---
a scangauge can be programmed for the speed offset when you
change tires...use a GPS for actual speed, and calibrate the speed
offset on the scangauge until it matches [both on highway and
around town] and then you will be able to get dead-accurate real MPG

 

What mpg loss you see will be determined by width, height, weight, tread patter, backspacing on the wheel, etc etc etc but I just wanted to point out that the tire size difference has nothing to do with predicting what decrease in mileage you will get. It is simply to get a proper calculation after the change.


That said. I was getting about 21.7-21.9 avg all summer and when winter hit, 4x4 plus cold start ups and running open longer, gas, etc all dropped me to about 18. That is about 4mpg drop just from summer to winter so you may just be experiencing that.


[On a personal opinion/side note: There is absolutely nothing wrong with monitoring and trying to get as good gas mileage as possible out of a pickup. Anyone who says that is quite dense. I enjoy getting 20% higher than EPA in the summer and extending the range of my vehicle. Money savings is simply a side perk. I do my best to get the greatest possible gas mileage out of every vehicle I own. Don't be ignant.]

 

This helps a lot. I know i'm letting it idle more in the morning and I only drive 15 mins into work everyday so it's hardly warmed up by the time I shut it down most of the time. Thanks, seeing your numbers helps ease my nerves some, I've never tracked my milage so closely with any other vehicle so it was a big shock to me this time.

I'll still be looking into syn diff oil and tire pressures.

Thanks all!


/thread closed

 

Sorry, I misread what you originally asked. 14 does seem pretty low and a big jump down from before.