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Old 06-20-2020, 10:03 PM   #15
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Without getting into all the numbers a 3500 SRW ( full 1 ton not 3/4 ton) should be the minimum choice. The price between a 2500 and 3500 is negligible however the 3500 gives you ample payload vs. marginal payload.
A dually is the ultimate, but I agree everyone does not need/want a dually.
However everyone should want a full 1 ton truck for the additional payload.
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Old 06-20-2020, 10:24 PM   #16
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Here is the 4080 rated tire size. https://m.tirerack.com/tires/Spec.js...rtnum=97R8DLTX
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Old 10-13-2020, 01:03 PM   #17
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I have a 2020 GMC AT4 crew cab long bed 3500 srw and the e rated tires that came with the truck LT27565R20 are rated at 3,750 a piece. I tow the Raptor 355 toy hauler 17,000 GVW when fully loaded I'm lucky to see 8mpg. Tows and rides great.
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Old 11-20-2020, 08:12 AM   #18
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Truck envy!

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Originally Posted by Bob Brooks View Post
Well, i sold my Cummins Beaver Monterey, loved it but it was time for a change, and i bought my new Duramax Chevrolet.
So far the fuel economy has been unbelievable on a drive from AZ to WA. I averaged over 21 MPG at posted speeds and a max of 70 on the higher speed highways. one 50 mile stretch coming down out of the mountains to I-5 actually got 35.9 MPG, crazy. The torque is incredible and the shifting is invisible.
Now comes the first test, i am leaving tuesday to go to central CA and pick up a 36' 5th wheel (about 16,000 lbs) so i will closely track fuel economy in both directions and let y'all know. Wish me luck!
This new Chev is insane with technology, i am still trying to learn it all.
All I could swing was an upgrade to my 2016 2500HD to a CPO 2018 3500HD both with the six-speed Allison! That tranny is a beast, I can only imagine what the ten-speed is capable of!!!!
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Old 11-20-2020, 08:15 AM   #19
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I have a 2020 GMC AT4 crew cab long bed 3500 srw and the e rated tires that came with the truck LT27565R20 are rated at 3,750 a piece. I tow the Raptor 355 toy hauler 17,000 GVW when fully loaded I'm lucky to see 8mpg. Tows and rides great.

Is your motor even broke in yet? My 18 Chevy has the same motor and my gross rig weighs in at 27k lbs. I only have 22k miles on the truck, but I can get 13.2 mpg on a low wind day at 60 MPH. When the truck was new, I averaged 9 MPG.
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Old Yesterday, 08:12 AM   #20
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Is your motor even broke in yet? My 18 Chevy has the same motor and my gross rig weighs in at 27k lbs. I only have 22k miles on the truck, but I can get 13.2 mpg on a low wind day at 60 MPH. When the truck was new, I averaged 9 MPG.
Just got back From a trip to Disney in Orlando 1,300 miles round trip now 17,000 miles on the truck and averaged 8.5 mpg according to the computer not manually checked. My old truck was a 2017 Duramax L5P 6 speed and 3.73 gears. and it got 10 MPG with the same trailer I tow at about 68-70 MPH. I think GM missed the mark by switching to the 3.42 axle ratio. With the 10 speed trans it is a better towing experience towing at slower speeds and even getting up to speed However at highway speeds it is constantly down shifting for any small incline or bridge where as the older set up with 3.73 axle ratio stayed in 6th gear unless there was a major incline. The constant down shifting is not only an annoyance it affects gas mileage the 3.73 with 10 speed would have been a much better improvement over the 3.42.
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Old Yesterday, 08:31 AM   #21
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Just got back From a trip to Disney in Orlando 1,300 miles round trip now 17,000 miles on the truck and averaged 8.5 mpg according to the computer not manually checked. My old truck was a 2017 Duramax L5P 6 speed and 3.73 gears. and it got 10 MPG with the same trailer I tow at about 68-70 MPH. I think GM missed the mark by switching to the 3.42 axle ratio. With the 10 speed trans it is a better towing experience towing at slower speeds and even getting up to speed However at highway speeds it is constantly down shifting for any small incline or bridge where as the older set up with 3.73 axle ratio stayed in 6th gear unless there was a major incline. The constant down shifting is not only an annoyance it affects gas mileage the 3.73 with 10 speed would have been a much better improvement over the 3.42.

I tow at 60 mph and that will make a HUGE difference in mileage and is the reason I get 13.2 per the onboad computer. The trans downshifting is not a good thing and a signal that your powertrain is struggling. For slight inclines, I will drop the cruise - button by 1-2 taps and regain the + button going down the other side.
The 3:42 gearing was meant to improve fuel mileage, if your truck struggles, then don't be afraid to run in a lower gear. I will wait for a couple of years until I try out the 10 speed and the bugs get worked out. The Allison 5-6 speed has a good 20 year record and is bullet proof.
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Old Yesterday, 01:36 PM   #22
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I tow at 60 mph and that will make a HUGE difference in mileage and is the reason I get 13.2 per the onboad computer. The trans downshifting is not a good thing and a signal that your powertrain is struggling. For slight inclines, I will drop the cruise - button by 1-2 taps and regain the + button going down the other side.
The 3:42 gearing was meant to improve fuel mileage, if your truck struggles, then don't be afraid to run in a lower gear. I will wait for a couple of years until I try out the 10 speed and the bugs get worked out. The Allison 5-6 speed has a good 20 year record and is bullet proof.
YEAAAAAA not going to drive 60 Just for a little better gas mileage. I drove the same speed in my 2017 and got better mileage. I have seen a little better mpg in the city but not much maybe 1 mpg better on the hwy empty around 20. When I expressed the same frustration to a GM engineer on a GM forum he said the new axle ratio was designed to use more of the transmission gears when needed instead of the higher axle ratio. The new trans is very smooth as compared to the 6 speed and no the truck does not seem to be struggling. However I do have take it off cruise in hilly areas. I think GM should at least give us a choice of axle ratios.
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