Anyone else fuel econ take a **** after duratracs

[PCT]

Hey all, I have been struggling with my fuel econ on my truck for the past year... At first I thought my exhaust was the culprit, 2 2.5 inch pipes, I reduced their size to 2.25, and noticed small gains. So I went back to the drawling board, and after almost 2 years it hit me when I noticed it took a ****, when I put the duratracs on... When I went from stock size SR/A, to 285 Terra g2, I noticed a slight drop as expected, went from 18-21hwy to 15-18 hwy. Now I'm getting 12-15 hwy, and truck constantly needs to shift when I give it a little power, I struggle to keep it above 70mph... I have never been stuck, but the fuel econ is killing me, I have thought about selling my truck at this point because I have no interest it anymore. Going to try tuning it, to see if I can recover my losses. Also I'm thinking of trading in duratrac for one size smaller duratrac.

Has anyone else noticed fuel econ suffer from duratracs? Or is there something else going on with my truck...

 

[yortnodnarb]

What size are they? 35's? Saying 285 means nothing except for the fact we know how wide they are.

 

[PCT]

What size are they? 35's? Saying 285 means nothing except for the fact we know how wide they are.

Sorry 285/70/17, 32.7inch
I'm thinking of moving to 275/70/17 32.2 inch

 

[Nick@GotExhaust]

Did you adjust your speedo after changing tires size? If you havent then your mpg calculations are incorrect.

 

[PCT]

Did you adjust your speedo after changing tires size? If you havent then your mpg calculations are incorrect.

At 70 MPH the speedo is 1.2 mph off, the MPG would not be effected by 3-4 because of a 1.2 mph differential, but its a noticeable lack of power. because when I had the nittos, they were the same size and got 15-18mpg

 

[warbat]

For what it’s worth, I have stock size duratracs on my truck (cc 4wd) and I get about 18 hwy with the 6 speed tran

 

[PCT]

For what it’s worth, I have stock size duratracs on my truck (cc 4wd) and I get about 18 hwy with the 6 speed tran

Did you ever have stock SRA? I think part of it is, I have a 4.7, so it struggles to over come road resistance.

 

[Yellow dog 55]

I have a V6, 2017 QC. I changed from stock 17”, to stock 20”. My truck was screwey until I got the computer flashed for the new size. After that everything went back to normal. I even gained 1mpg on the highway. Lost 1mpg city. I’m on the fence right now as I want to upsize my tires by one size but I scared it will screw things up again.

 

[warbat]

Did you ever have stock SRA? I think part of it is, I have a 4.7, so it struggles to over come road resistance.

I did not. However, I had a 2011 4.7 QC 4wd and when I went from the SR-As to duratracs (factory size) I lost 1 mpg.

 

[Addicted2fishing]

I went with duratracs for a couple reasons. One of them is they almost weigh as much as stock SR-A tires and the size is roughly the same. I think the tread pattern makes it slightly larger. I could be wrong....

The stock ones are roughly 42 pounds I believe and duratracs are 50 pounds I believe

I noticed a drop in Mileage but nothing crazy. Something else must be going on with your truck.


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[Nick@GotExhaust]

At 70 MPH the speedo is 1.2 mph off, the MPG would not be effected by 3-4 because of a 1.2 mph differential, but its a noticeable lack of power. because when I had the nittos, they were the same size and got 15-18mpg

but it will throw your transmission off slightly and that will definitely make your mpg vary as the shift points can be off now. Calibrate your speedo and I bet most of your MPG comes back

 

[TomT]

but it will throw your transmission off slightly and that will definitely make your mpg vary as the shift points can be off now. Calibrate your speedo and I bet most of your MPG comes back

What Nick said about shift points being off is absolutely true. I put on 35s (Toyo A/T) about three months after getting my new truck. I drove it for two and a half years and it seemed to have lost a step unless I nailed the throttle.

I bought a Pedal Commander roughly a year ago (I’m terrible with time) and that made it a bit more fun to drive. Last month I bought the Rough Country Speedo Calibrator. Once I calibrated it, everything just worked better as far as the transmission is concerned.

I don’t track mileage so I can’t say for sure if it helped, but it definitely made it feel like it did before the larger tires went on.

 

[darren Toth]

It is definitely not the Duratracs as the Nittos are heavier. The 285/60/20 Duratracs I had were 58lb and the new Nittos I have now are 64lbs. I noticed a small decrease in mpg going to the Nittos

 

[Seth_5.7]

I'm leveled on Bilsteins with 35x12.50 tires on 20x12 Moto metals. A few days ago I went to a performance shop and got my catalytic converters removed and a street tune. I went from getting 11mpg to 17mpg around town and up to 20 on the highway. The tuner guy said my speedo was 5 mph slow at 60mph, and that I should've gained anywhere between 35 and 45 hp from getting the tune and cat removal.
So a tune might just do what you are looking for to get some of your mpg's back

Sent from my SM-G920P using Tapatalk

 

[NCRaineman]

I'm leveled on Bilsteins with 35x12.50 tires on 20x12 Moto metals. A few days ago I went to a performance shop and got my catalytic converters removed and a street tune.

Hope you don't live in a county where emissions inspections are required... also hope that your county doesn't grow in population too much in the next few years, b/c that's how the state determines if they have to test emissions or not. One sniff of the tailpipes with no cats installed and you'll get a big ol' FAIL from the State.

Good luck!

 

[Seth_5.7]

Hope you don't live in a county where emissions inspections are required... also hope that your county doesn't grow in population too much in the next few years, b/c that's how the state determines if they have to test emissions or not. One sniff of the tailpipes with no cats installed and you'll get a big ol' FAIL from the State.

Good luck!

My county does emissions inspections, but only with the thing they plug into the OBD reader. The tune I got made it so that the o2 sensors are constantly in a ready state which will pass on their OBD inspector, and they don't do visual inspections. In 2020 my state is completely getting rid of emissions testing so I'm not too worried about it

 

[NCRaineman]

My county does emissions inspections, but only with the thing they plug into the OBD reader. The tune I got made it so that the o2 sensors are constantly in a ready state which will pass on their OBD inspector, and they don't do visual inspections. In 2020 my state is completely getting rid of emissions testing so I'm not too worried about it

Consider yourself fortunate. My county has a tiny population so doesn't do emissions at all, but back when I lived in Charlotte the inspection procedure included sticking the tailpipe.

Where did you hear that NC is getting rid of emissions testing in 2020? This is the first I've heard of it.

 

[Seth_5.7]

Consider yourself fortunate. My county has a tiny population so doesn't do emissions at all, but back when I lived in Charlotte the inspection procedure included sticking the tailpipe.

Where did you hear that NC is getting rid of emissions testing in 2020? This is the first I've heard of it.

A few mechanics I've talked to and there are a few news articles on it. Although I should revise my statement as it said 26 out of 48 counties will no longer be required to do emissions testing, not the whole state.

 

[NCRaineman]

A few mechanics I've talked to and there are a few news articles on it. Although I should revise my statement as it said 26 out of 48 counties will no longer be required to do emissions testing, not the whole state.

I'd say probably half of the counties in the State aren't populated enough to meet the current level for emissions testing anyways, so if 48 counties are currently testing and 26 of them will no longer have to after 2020 that's pretty significant.