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Old 04-17-2016, 07:05 PM   #1
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Towing mpg with 6.4L Hemi

I pulled a large trailer for the first time last fall and the mileage I got was worse than expected. I'm hoping to get some feedback to see if my expectations were too high or if there's room for improvement, maybe by changing gearing or fixing some unknown malfunction.

My truck is a 2015 Ram 2500 4x4 Club Cab with the 6.4L Hemi. It has factory 3.73 gears and factory tires. Tire pressure was set to recommended before the trip.

My trailer is a 28' toy hauler, bumper pull, about 11.5' tall. Loaded weight was about 10,000 lbs.

I know mileage is generally pretty miserable when towing with a gasser, but I was thinking I'd get 7-9 mpg, considering my trailer isn't as tall as many of the 5th wheel campers I see, and the weight was well under the 16,000# max towing rating (I've since learned that 16k is only for trucks with 4.10 gears, 3.73 gears puts my max tow rating around 12k).

My actual mileage averaged about 5.5 mpg over the 3000 mile trip. What really hurt was the sections in west Texas where I was only getting about 4 mpg. I ran out of gas a couple times, luckily I had a couple filled gas cans in the trailer.

I'm thinking speed is what really hurt me. The truck handled the trailer quite well, and I was driving at least the speed limit, even where the limit is 80 mph.

However, I also noticed that the transmission seemed to stay in 3rd gear a lot, like the truck just didn't have enough torque to hold 4th. I'm thinking 4.10 gears would help with that, but would it improve the mileage any? I experiment with Tow/Haul on and off, but it didn't make a huge difference.

I look forward to reading what other people are experiencing. That is, if they're willing to admit how bad their mileage is!

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Old 04-17-2016, 07:09 PM   #2
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Old 04-17-2016, 07:25 PM   #3
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Gearing it would deff be the best idea. Running in the higher gears will lower the rpm and decrease the load the engine has to deal with. So I would imagine that gears and getting into higher gear alone will help bring that up
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Old 04-18-2016, 09:15 AM   #4
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Old 04-18-2016, 09:59 AM   #5
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I'm an absolute believer in the 4:56 gears - I drove out that way and past Kerrville where you can legally hit 80 (most going closer to 90) my mileage didn't suffer at all in a 4x2 Quad Cab 5.7 - so I would think with correct gearing you should get better overall mileage and do the same pulling a load with your 6.4 .


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Old 04-18-2016, 11:03 AM   #6
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IMO, regearing to 4:10 or 4:56 would help you out. However with a 2500 4x4 doing both axles you would be at a guess around $3500 into the change. That buys a lot of gas.. What mileage do you get unloaded?
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Old 04-18-2016, 11:27 AM   #7
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Depending how late last fall you road tripped, you may have already been getting winter mix gas. That would negatively affect MPG also.
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Old 04-19-2016, 07:35 PM   #8
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Originally Posted by Redtruck-VA View Post
IMO, regearing to 4:10 or 4:56 would help you out. However with a 2500 4x4 doing both axles you would be at a guess around $3500 into the change. That buys a lot of gas.. What mileage do you get unloaded?
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I get about 14 mpg unloaded when I keep my foot light. That's calculated, the dash says 15mpg.

I don't tow that often so maybe it wouldn't be worth changing the gears. I think the fact that I had to stop for gas so often bothers me more than the cost. That made the trip more stressful and longer than anticipated. Maybe I need to find an a way to add some fuel capacity for the occasional long distance trips I'm planning to take.
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Old 04-19-2016, 07:41 PM   #9
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That's exactly what my '11 5.7 hemi does unloaded with 4.10 gears. Well, I've got a 200 lb front bumper and 200 lbs of tools in the toolbox so unloaded is a relative term
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Old 04-19-2016, 08:03 PM   #10
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Quote:
Originally Posted by Playful Badger View Post
I get about 14 mpg unloaded when I keep my foot light. That's calculated, the dash says 15mpg.

I don't tow that often so maybe it wouldn't be worth changing the gears. I think the fact that I had to stop for gas so often bothers me more than the cost. That made the trip more stressful and longer than anticipated. Maybe I need to find an a way to add some fuel capacity for the occasional long distance trips I'm planning to take.

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A bigger tank is always better no matter what the fuel mileage IMO. Maybe improve your exhaust system too should help at least a little .


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