im still getting 13 to15 mpg took her back an they said not showing no codes . cant figure it out everyone i talk to is getting 20 mpg

 

I get 13 - 15 around town and 17 highway with pretty much stock everything. Better than I expected for a big heavy truck.

I don't see how people are averaging 20mpg on the highway in a stock truck unless they're going 55 mph or less with a no hard acceleration whatsoever.

JD

 

I get 13 most of the time.
17-18 on the highway yesterday but it's been awhile since I've seen the MPG that high.

 

they are going 55 mph and reseting the lie-o-meter going a mile then stopping and calling it 20 mpg. I do not think it happens the truck weighs 8000 pounds it is not going to get 20 mpg constant driving it may say it for a few miles but nobody is getting that on average for a tank of fuel....... enjoy getting 17 and call it a day.

 

Yes, most people reset the mileage thing after they have gotten going. I can eek out 18-19 if I really baby it, don't stop for anything for 200 miles or more.

17 is good

 

18 if I'm lucky. Since purchase I'm averaging 17.5 bone stock, some towing mostly empty.

 

I just got back from a 500 mile round trip down to Illinois for the weekend. I wasn't towing anything (for once) and got 17.0 on the way down and 16.8 on the way back. There was a lot of traffic to pass on the way home. I wasn't beating on it, but I wasn't taking it easy either (prolly averaging 75 mph or so). I was happy with my mileage with the 35's. Not bad at all. 2 regens total (that I noticed). Once on the way down and once on the way back.

 

last week i drove to montgomery and back (about 65 miles each way). I hit reset when i got on the interstate and when i pulled in to my driveway at the end of the day i averaged exactly 20mpg. That was setting the cruise at ~69mph and taking it easy on the little bit of intown driving i did at each end of the trip.

cruising around town (back and forth to work 8 miles each way) i get between 16-17 when i take it easy. If i drive a little more aggresive it drops to 15.

 

I THINK I GT 331 GEARS MIGHT BE MY PROBLEM TO HIGH

 

When my rig was stock (no lift, big tires etc) I would get over 20 mpg at 70mph hand calculated and by lie-o-meter. That was also in central IL where we have an abundant amount of bio-blend diesel. When I traveled out of state where there was "normal" diesel and less wind (IL is windy as all can be), I got even better mileage.

Even when lifted etc, I averaged 18.9 mpg coming from central MO to central IL using "normal" diesel". Take off about 3-4 mpg for bio-blend from my experience.

I had the 3.55 elec locker.

 

If you have a 3:31 ratio, that would incrementally improve your mileage. The lower the ratio, the higher the number (as in 4:10) and in theory, the lower the fuel mileage. From what I've read, there is only a small difference in mileage between the 3:55 or 3:31 but the 3:31 gearing would be better.

And incidentally, on the highway I can get 20mpg (hand and computer calculated) but again, that's on the highway (80% of my driving). After a month in my new truck I have 6500 miles and I am averaging 17.5 mpg in overall mileage. That includes city, highway and some towing.

 

3:31 with 18" wheels and 3:55 with 20" wheels equal out

 

How does that work if the circumference of the tire is the same? Just because the wheels may be different circumference, the tires may or may not be a different?

 

I know it's strange but stock 18"s come with higher profile tires (85) and 20"s come with 65's. So the actual circumference is nearly identical. Once we go with new tires and change the sizes things are different if one chooses to change it.

Don't quote me on the 85 profile for the 18" wheels, that's just a guess. It could be 75 or 95, I'm not sure. They are taller than the 20" tires though.

I just got 55's put on a couple weeks ago and on 20" wheels they result in my speedo being 5mph fast. I shoulda got 65's but with the 295 width I was afraid they would rub. I've got to get my dealer to adjust my truck to think it has smaller wheels.

 

then state overall circumference...not wheel diameter