Yes I was aware of the difference in distance and I know I was out by about 5%. That said I have finally had the chance to try some other tires and I'm completely blown away by the results. UPDATE: My last tank I swapped the tires around the 60km mark on my trip display. (I reset the trip A display every fillup and completely fill every tank) I swapped to a set of slightly used studded winter champiro ice pro 2s tires) they are on 18" rims and they are less than 1% larger than stock if they had full tread. They have approx 70% tread left. New tires are also 35psi as they were mounted by the dealer and that's what our trucks are rated for stock. Just on this tank since changing tires only (still no air dam) I have dropped my average economy to 14.5l/100 kms based on the cluster calculation. About 15.5 when doing actual calculation. My driving habits I've tried as hard as possible not to change but I did have one more 60km "highway" trip than usual. This puts me over 15mpg and I expect the next tank to be better again without the first few kms of oversized tires. It's still not as good as I'd like but way better than I was getting. Sent from my SM-G930W8 using Tapatalk
I realize both of you are likely to argue this to the end, but either way there is no solid proof that with our trucks you gain or lose any fuel economy with a tonneau. Everything I can find with documented proof behind it says you will get better fuel economy with a tonneau but never enough to justify buying it for that reason alone. And the fuel savings only happen above 55mph (100km/h) range. Even at that it's such a small difference it's barely measurable. The only reason you would lose fuel economy would be because of the added weight which makes sense in stop and go situations. I have a tonneau for functionality and cosmetic reasons. Not for fuel economy. Please leave the debate in another thread if you two want to hash it out as I'd like to leave others here some useful info and results from my personal experience. Thanks [emoji16] Sent from my SM-G930W8 using Tapatalk
I also found this to be a good scientific read but unfortunately only tests older trucks and it's a very old study now. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.agricover.com/downloads/pdf/2007_windtunnel.pdf&ved=2ahUKEwiz0eiJ27nfAhVizlQKHXVJBSg4FBAWMAB6BAgCEAE&usg=AOvVaw3G3799ApMcBgQEbTxbOpp6 I'd love to see someone put to bed the myth but there's contradicting info everywhere. Mythbusters made a basic attempt at it and the results were basically within margin of error. So my take from it is, tonneau covers can save you fuel IF the truck can benefit from the lower air drag due to poor design or mods that change the drag of the vehicle. (Like a lift) Honestly the 2 best tanks I've had since I bought the truck were both using premium fuel. 91 octane made a bigger difference in fuel economy than any other fuel consumption "improving" mod so far. But more testing needs to be done... Sent from my SM-G930W8 using Tapatalk
Excellent info here thanks. I didnt realize the tire weight difference was so drastic. Being that most of my mileage will be put on in the winter I'll try some winter tires/rims if I can find a good deal and see how the mileage looks. Went to put the air dam back on this afternoon and I cant find the stupid screws that they gave me when they took it off. Guess I'll have to wait till after christmas. Sent from my SM-G930W8 using Tapatalk
The tires are LT. Goodyear wrangler duratracs. I was a bit disappointed they sold them to us as "stock" as they didnt calibrate the truck computer/speedometer to match them. They also rub on the upper control arms so now there is no paint on the spot they rub on. But that's an entirely different issue. I run them around 36 psi at 0*C and was thinking over inflating them a bit might help a tiny bit too. Air dam will go back on as soon as I can find the time and the 70 screws that the dealer handed us in a bag when they took it off. My big issue is the 3 co-workers I have with the same truck (2 2016s and a 2017) are getting way better mileage than me. But they also all have 20000-40000 kms on their vehicles and theirs are basically stock compared to mine. I'll continue to keep an eye on things and report back if I find anything substantial. I'm always open to ideas in the mean time as well. Thanks! Sent from my SM-G930W8 using Tapatalk
Hello all! I've been reading posts on this site for the past 2 months or so to learn as much as possible about my 2018 sierra 1500. I'm having a horrible time getting fuel consumption under control and I'm extremely confident my "old man" driving should be netting me much better fuel economy than what I am getting. I have a 2018 gmc 1500 sle elevation edition w kodiak package. crew cab, reg box, 5.3l 4x4 6 speed. At the dealer I added the leveling kit, oem running boards, removed the air dam and upsized the tires to 285/60r20 on the stock wheels. I added a hard tri-fold tonneau cover recently as well. I've never owned a new vehicle before so all of this is a learning curve for me. The dealer keeps reassuring me my mileage will come down in time after break-in etc but every tank is a tiny bit worse and it's getting a bit concerning. According to my cluster and GMC app I have averaged 16.1 l/100 km (14.6 mpg) since the truck was new. Now according to my Drivvo app I am averaging around 18.0l/100km (13 mpg) which is also what my math comes out to when I calculate it myself after the past few fillups. I realize I have a few "bad for economy" mods on the truck but really my questions are: 1. Having only 3500kms on the truck so far, is the lack of break-in really the problem? 2. Has anyone else noticed the fuel consumption display in the truck being off by this much? 3. Should I look at a tuner/tune to update the computer with the proper tire size and try for a tune that's better on fuel? I dont plan to tow anything with this truck other than dirt bikes in the box in the summer time, and I realize it's a truck not a car etc etc, but I have read enough posts to know I'm using almost 40-50% more fuel than the average person on here so I really just want to know what could be the issue considering the truck is literally brand new... I am realistically 50-50 highway vs city driving. Thanks in advance!
Im very impressed by the work you are doing here @GTPprix! I just bought a 2018 SLE gmc sierra and I was hoping there was a way to swap the cluster to the red denali one and hopefully my stereo bezel colors later to match. The blue/green is one of the few things I cant stand about this truck. Is it possible to swap a 2016ish cluster into my 2018 with your help? Without losing any functionality of course. I also have another completely different request that is audio related I'm hoping you can help with. Please PM me when you have a spare minute!
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