SRich2015
Senior Member
At what Speed 90mph??? Ya, if you run 80+ you may want to run 3.73's but for pulling heavy at 70mph 4.10's are great!! But this is my opinion and everyone is free to run the gears they want!!
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I re-geared mine to 4.10
I hauled some cows with it the first time.
Not going to lie - I would really like to drive a 2500 6.7L very similar to mine with 3:73s or 4:10s - pulling the same 12K lb trailer just to compare.
I've read a article along time ago stating the same info as posted above - Cummins and Ram both agreed 3:42s was Ideal for the 6.7L in the 2500 - to compliment the sweet spot of the torque curve of the 6.7L engine.
I have only towed 4 or 5 times with my new 6.7L and I did it in tow haul mode and never went past 5th gear @ 65mph and she pulled 10K-12Klbs effortlessly it seemed.
Temps were all in the ideal range & RPMs never were an issue.
But with that said: I towed mostly on flat interstate,all trips were around 273 miles round trip- No Mountain passes...
Here is what you said previously said; "3.42's have no place behind the Cummins!! IMO Yes they are good for fuel mileage empty on the highway"
They do it just fine. Like I said in an early post, I can easily reach 65 MPH on a freeway acceleration ramp pulling 15,000 pounds. You have never driven a RAM Cummins with 3:42 axle ratios pulling a 15,000 RV. How do I know this? Because of what you said. If you get the chance to drive one, you will be pleasantly surprised.
4:10s do not keep the Cummins in the sweet RPM spot any better than any other axle ratio since it is MPH based. First off, the Cummins sweet spot is 1,600 to 2,200 RPMs, these numbers come from the Cummins' Powerspec application (free to download and use). The RAM Cummins will pull at 1,850 RPM, 5th gear, at 65MPH all day, right in its sweet spot.
I see the standard axle in the 2020 Ram 2500 CTD is back to the 3.73 ratio. I guess FCA has heard some complaints, but like I said that is just a guess.
I have a question for Syn. Are the 285/70/20 the stock setup? My 2013 2500 3:42 came with 245/70/17. They look small. Everyone ask why I have such little wheels.