385 hp @ 2,800 rpm

[silverhocummins]

HiAnyone have the new 2013 with the increased horse power and the new tranny? 385 hp @ 2,800 rpm 850 lb-ft @ 1,600 rpm (Aisin AS69RC trans)Also, I do not do very much towing at all. I normally always run empty etc. What would the best rear end gears should I get to maximize my mpg?:cookoo:

[mr.mindless]

3.42s if you can get em. You want to cruise at to just above peak torque for best economy. If you don't tow, the tallest gears you can get will universally do you best - unless you're 100% stop and go city stuff, and even so I bet you'd still be best considering the power the diesel makes. Tapatalking in traffic

[silverhocummins]

Excellent thanks.

[silverhocummins]

Looking at some left over 2012's right now will let you know. The price keeps dropping..haha sweeeeeeeeet.

3.42s if you can get em. You want to cruise at to just above peak torque for best economy. If you don't tow, the tallest gears you can get will universally do you best - unless you're 100% stop and go city stuff, and even so I bet you'd still be best considering the power the diesel makes. Tapatalking in traffic

[flagmanruss]

Unless you are going to install really big tires, you DON'T want 4:10s or such. I just can not equal the mpgs of the stock ratio. Really, with OEM tire sizes, the factory is pretty spot on with efficient ratios. Guys with stock ratios tow as much (or more) than me, quieter & easier. It's very though because we're buying a tow vehicle but can only test it empty or bumper tow.

[silverhocummins]

Are 4:10s too low? Ie too high rev? For summer I will put on my 35's.

Unless you are going to install really big tires, you DON'T want 4:10s or such. I just can not equal the mpgs of the stock ratio. Really, with OEM tire sizes, the factory is pretty spot on with efficient ratios. Guys with stock ratios tow as much (or ore) than me, quieter & easier. It's very though because we're buying a tow vehicle but can only test it empty or bumper tow.

[flagmanruss]

I can't stand the screaming motor with OEM rubber listed in my signature. I know it's not recommended but I end up towing with the OD in. If I have trouble on hills, I have to quickly kick the OD out & cut road speed to 50-55 to boost the RPM. I can't afford to regear the truck but listening to the salesman (who said 4.10s was the gear to get, when he would have told me anything just to sell the truck on his lot) was a mistake. I have to downshift less with the XZT+. I don't have big rubber. I'll let those who have first hand experience answer your specific questions.

[mr.mindless]

With 35s I think you'd be happy with 4.10s. Anything smaller and they're just plain too deep. I've got 245/70r19.5s on which is about a 34" tire with 3.42 gears. It's not lacking. I haven't grossed more than maybe 20,000 with this setup though. I may be wanting when I'm at 26k with three cars behind me. Tapatalking in traffic

[flagmanruss]

With my OD automatic, 4.10s are fine for grocery hauling & running light on the highway... with the stock tires. It's just towing where it's to noisy. If you don't tow at highway speeds with your winter tires, I doubt you'll even notice.

[silverhocummins]

Ok

I really dont tow hardly ever. But love the look and bounce of the 35 ATs. I just wanted my best mpg I can get out of the truck as it is a big expense over the years for fuel etc.

With my OD automatic, 4.10s are fine for grocery hauling & running light on the highway... with the stock tires. It's just towing where it's to noisy. If you don't tow at highway speeds with your winter tires, I doubt you'll even notice.

- - - Updated - - -

But just running some numbers, with whats left for 2012's (only a few) I save 15,000 plus tax= savings $17,100.

Guess that would buy a lot of diesel fuel, thinking about it.

Ok

I really dont tow hardly ever. But love the look and bounce of the 35 ATs. I just wanted my best mpg I can get out of the truck as it is a big expense over the years for fuel etc.

[Mopar1973Man]

Just remember for every 4 pounds of tire rubber you put on the rim will cost you 1 extra HP to keep the truck moving. So smaller and lighter tires will do more good for MPG's that big over-sized aggressive tires.

[silverhocummins]

Ok thanks Mopar. I keep hearing mixed stuff online but know 4.10 is fairly low. Just no other options on the lots so its either buy one or forget it. I was reading alot about oversized tires making the 4.10 more rev friendly so I thought maybe it would compensate.

Just remember for every 4 pounds of tire rubber you put on the rim will cost you 1 extra HP to keep the truck moving. So smaller and lighter tires will do more good for MPG's that big over-sized aggressive tires.

[Mopar1973Man]

As for speaking from a 2nd Gen point of view. Actually you want to cruise at the lowest possible RPM without struggling the engine. Like myself I can cruise at 1,500 to 1,600 and get upwards of 20 MPG without thinking. If I was to drive close to my torque curve which is 2,100 RPM's I would be doing close to 75 MPH which the last time I traveled the interstate I was getting about 14 MPG (ScanGauge II). So the torque curve thing is more so if your hauling heavy. Like now if I'm towing my RV I aim for the 2K on the tach and still pull 14 MPG at 55 MPH in 4th Gear. I'm running 3.54:1 Gear ratio and 235/85 R16 tires (weighing 62 pounds per tire). But since I've never seen a 6.7L Cummins yet I couldn't even tell you. Everything in my neighborhood is 1st gens to 2nd Gens... Very rare to see 3rd gens...

[silverhocummins]

Ok good specs. Thats what I meant by having 3.73s or something instead of 4.10s. Maybe I am confusing them or something. I thought 4.10s were lower gears which means higher revs. But if you put bigger tires you can change the ratio a tad ie lowering the 4.10 say to 3.73is etc. Anyways, I am going to call dealer today and see if they can go any lower. The truck is 65k sticker and they want 51.

As for speaking from a 2nd Gen point of view. Actually you want to cruise at the lowest possible RPM without struggling the engine. Like myself I can cruise at 1,500 to 1,600 and get upwards of 20 MPG without thinking. If I was to drive close to my torque curve which is 2,100 RPM's I would be doing close to 75 MPH which the last time I traveled the interstate I was getting about 14 MPG (ScanGauge II). So the torque curve thing is more so if your hauling heavy. Like now if I'm towing my RV I aim for the 2K on the tach and still pull 14 MPG at 55 MPH in 4th Gear. I'm running 3.54:1 Gear ratio and 235/85 R16 tires (weighing 62 pounds per tire). But since I've never seen a 6.7L Cummins yet I couldn't even tell you. Everything in my neighborhood is 1st gens to 2nd Gens... Very rare to see 3rd gens...

[AH64ID]

It's impossible to compare anything from pre-6.7 with 4.10's to a 6.7 with 4.10's. The auto is the only trans offered with 4.10's, and with the double OD's you cruise at low rpm's even with 4.10's. 4.10's offer 20% more torque to the wheels and gear reduction than 3.42's. Here are some rpms to compare, all assuming stock (265/70 or 265/75 tires) 47RE ~2175 NV4500 ~2350 NV5600 ~2300 48RE ~2175 68RFE ~1975 AS69RC ~1975 As you can see a 6.7 will run considerably lower rpms cruising, even with 4.10's. Many people tow very heavy with 3.42 equipped 6.7's, but the load negates the use of 6th gear and 1st is under geared, but once your moving it works well (from reading about people with them). Personally I wouldn't own a 6.7 with an auto trans and 3.42's if 4.10's were an option. Fuel mileage is negligently different between the two. The fuel saved from lower rpms is not enough to counteract the fuel required to make the additional torque at the engine instead of the rear-end and show a big increase. I saw "were" and option because as of 2013 the only ratio offered in a SRW configuration. The 385hp motor is only offered in the 3500 trucks equipped with the AS69RC transmission, SRW and DRW. It's a $$ option geared towards the buyer that tows heavy and often.

If I was to drive close to my torque curve which is 2,100 RPM's

Where do you pull that number from? OEM rating was 1,400 rpms wasn't it?

[mr.mindless]

I can cruise at 1,500 to 1,600 and get upwards of 20 MPG without thinking. If I was to drive close to my torque curve which is 2,100 RPM's I would be doing close to 75 MPH which the last time I traveled the interstate I was getting about 14 MPG (ScanGauge II).

Comparing those numbers is totally apples & oranges. I'd expect your peak torque is around 1800-1900 but ignoring that you're talking a 20mph speed differential. Making a run in 5th vs 4th (or 6th vs 5th) or swapping gears is the only way to make that comparison. How accurate is your scangauge to pump-odometer numbers? I'm trying to "train in" my Edge Insight CTS and a couple thousand miles in its still wildly off. The current tank it's way low. It's been way high until now. The overhead computer has been decenty close the whole time. I think 15% off is the worst I've seen. Tapatalking in traffic

[silverhocummins]

I got the 2012 with 410's. Got a great deal on it.Love the truck. Harder on fuel to start around town then the 03, 5.9 but same on the highway on a cpl hr trip.

[millco]

To really know what the rpms will be you need to use a spreadsheet like this one: http://www.klenger.net/RVing/Towing_Dodge-CTD/general-reference/gear-speed-calculator.pdf This guy has done a really good job over the years of keeping up with changes Dodge has made in transmissions and gears. It is a really useful calculator to bookmark!!

[CUMMINSDIESELPWR]

http://www.klenger.net/RVing/Towing_Dodge-CTD/general-reference/gear-speed-calculator.xls this link brings up the xls file that you can manipulate for different tire sizes. handy tool thanks!

[Rogan]

my '97 47re w/4.10s runs about 2350 @ 65 on 245/75-16s. buzz buzz...