4.56 or 4.88 gears for towing with 6.4 Hemi?

[MetalGrand]

I’m looking to regear my truck and was wondering which I should go with? I have 35” tires and a 12k fully loaded 5th wheel I tow just about every month. I currently have 3.73’s on my ‘18 2500 6.4 and going up 6-7% grades aren’t the best times that I have. Looking for what would suit me best.

 

[AFMoulton]

@U&A has 4.88s, he will tell you to go 5.13s

And based on what you are saying you have an do with it, I’d get 5.13s also.


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

 

[U&A]

@U&A has 4.88s, he will tell you to go 5.13s

And based on what you are saying you have an do with it, I’d get 5.13s also.


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

Spot on.

4.88’s are good with 35’s. 5.13’s are a better choice from my experience.

Id do 5.13’s with NO HESITATION if i could do it over again


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[MetalGrand]

Spot on.

4.88’s are good with 35’s. 5.13’s are a better choice from my experience.

Id do 5.13’s with NO HESITATION if i could do it over again


Sent while firmly grasping my redline lubed RAM [emoji231]

How is 5.13’s going to affect my daily driving?

 

[dhay13]

With 35's I'd go with the 4.88's. 4.88's with a taller tire will be closer to stock tires with 4.56's. You'd have to pull out a ratio calculator to get exact numbers but I'm just 'guesstimating' here. 12k is pretty heavy. We just towed my sons TT 1400 miles with his 2018 2500 6.4 with 4.10's. Total weight was 16180 CAT scaled (TT was about 8100lbs) but we were on mostly flat ground. It towed it with ease. I think it would have been fine with 10k but pretty sure 12k would have been a strain.

How much driving do you do not towing? Highway or in town? If in town at lower speeds then maybe 5.13s wouldn't be bad but if you spend alot of time on the highway at higher speeds then maybe 4.88s are the way to go.

 

[Bldrinker]

I just got 4:88’s. I have 34” tires. Freeway is 70/75mph. Tow with it first time next weekend. My toy hauler is 10k empty 14k loaded.
It’s much better in town.

 

[U&A]

How is 5.13’s going to affect my daily driving?

Your truck still has stock trans programming so it will just get to 6th faster. Its not like you will run higher rpm in each gear it just goes through them faster.

You will be a bit over 2000RPM at 70. Probably around 2200-2300. That is perfect for cruising. My MPG went UP when i went to 4.88. Less effort for the truck to get 7,000 moving. Les effort = less fuel. Just dont drive like a race car.

5.13 will just five you way more torque at the wheel.

Good luck on your endeavors sir. [emoji41][emoji1303]


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[U&A]

http://www.grimmjeeper.com/gears.html

In the drop-down menu select 68 RFE as it has the same exact final drive gear ratios as the 66

Ignore everything else and just put in your tire size and gear ratio. Then you can play with the charts below it. Add about 50-100 RPM for air resistance


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[MetalGrand]

I drive mainly highway to work. I drive about 15 miles to work and cruise the freeway around 75mph but tend to speed a little.

 

[Bldrinker]

Your truck still has stock trans programming so it will just get to 6th faster. Its not like you will run higher rpm in each gear it just goes through them faster.

You will be a bit over 2000RPM at 70. Probably around 2200-2300. That is perfect for cruising. My MPG went UP when i went to 4.88. Less effort for the truck to get 7,000 moving. Les effort = less fuel. Just dont drive like a race car.

5.13 will just five you way more torque at the wheel.

Good luck on your endeavors sir. [emoji41][emoji1303]


Sent while firmly grasping my redline lubed RAM [emoji231]

Are you saying 2000rpm with stock tires and 5:13?

No way. Unless my truck is broken. I’m over that with 4:88 and 34’s

 

[U&A]

Are you saying 2000rpm with stock tires and 5:13?

No way. Unless my truck is broken. I’m over that with 4:88 and 34’s

No

35’s like the op said. I have 35’s and 4.88’s
Add an inch of tire and you go faster with the same RPM


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[Bldrinker]

No

35’s like the op said. I have 35’s and 4.88’s
Add an inch of tire and you go faster with the same RPM


Sent while firmly grasping my redline lubed RAM [emoji231]

My bad I saw stock Trans programming and got stock tires stuck in my head somehow.

 

[U&A]

My bad I saw stock Trans programming and got stock tires stuck in my head somehow.

NP man

Just trying to help from my experiences

Last thing.

Hemi owners (and all in the world today) need to not be so concerned about RPM being high. Cursing at 2,500 rpm all day in 5th i get better gas milage than crusing in 6th at 2000rpm.

Engines are not efficient below their power bands like the manufacturers want us to think. GET THEM RPM UP![emoji38][emoji38][emoji41][emoji1303]


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[tron67j]

An alternative thought, you might want to consider a 3500 with the gearing you desire. A 12,000 trailer has a pin weight of about 2,400 dry weight pounds, plus about 400 pounds hitch and fuel, and if your configuration has a payload of 3,140, you have about 300 pounds left for people, pets, and gear in trailer that increases pin weight. You could also look at upgrading rear spring packs to 2500 set, maybe they fit in to same connection points(?).

 

[AFMoulton]

An alternative thought, you might want to consider a 3500 with the gearing you desire. A 12,000 trailer has a pin weight of about 2,400 dry weight pounds, plus about 400 pounds hitch and fuel, and if your configuration has a payload of 3,140, you have about 300 pounds left for people, pets, and gear in trailer that increases pin weight. You could also look at upgrading rear spring packs to 2500 set, maybe they fit in to same connection points(?).

2500’s are coil springs, so no upgrade.


2018 Ram 2500 6.4L 4x4
Amsoil SS 0W-40

 

[Bldrinker]

An alternative thought, you might want to consider a 3500 with the gearing you desire. A 12,000 trailer has a pin weight of about 2,400 dry weight pounds, plus about 400 pounds hitch and fuel, and if your configuration has a payload of 3,140, you have about 300 pounds left for people, pets, and gear in trailer that increases pin weight. You could also look at upgrading rear spring packs to 2500 set, maybe they fit in to same connection points(?).

Don’t believe the 3500’s come with anything over 4:10. I believe the spring rate and door sticker is the only difference between 2500 & 3500.

not that it’s legal but there are thousands upon thousands of 3/4tons out there with way more load than the OP will have.

 

[U&A]

Don’t believe the 3500’s come with anything over 4:10. I believe the spring rate and door sticker is the only difference between 2500 & 3500.

not that it’s legal but there are thousands upon thousands of 3/4tons out there with way more load than the OP will have.

3500 srw can handle WAY more weight in the bed than a 2500

They have super stiff leaf springs in the back. Iv had 4,000 lbs in my 3500 srw bed and she eats it up and has room for more.

Just my experience [emoji1303]


Sent while firmly grasping my redline lubed RAM [emoji231]

 

[MetalGrand]

An alternative thought, you might want to consider a 3500 with the gearing you desire. A 12,000 trailer has a pin weight of about 2,400 dry weight pounds, plus about 400 pounds hitch and fuel, and if your configuration has a payload of 3,140, you have about 300 pounds left for people, pets, and gear in trailer that increases pin weight. You could also look at upgrading rear spring packs to 2500 set, maybe they fit in to same connection points(?).

Ideally in the future I would like to get a 3500 SRW Cummins, but that won’t be for about 4 more years so I am looking for the best options to hold me over until that time.

 

[Bldrinker]

3500 srw can handle WAY more weight in the bed than a 2500

They have super stiff leaf springs in the back. Iv had 4,000 lbs in my 3500 srw bed and she eats it up and has room for more.

Just my experience [emoji1303]


Sent while firmly grasping my redline lubed RAM [emoji231]

I understand that. But isn’t the axle same?
If so a 2500 will do the same a 3500 will if you ad bags to support the weight. You just won’t have the sticker to say it’s ok is all I’m getting at.
And I was responding to the guy that suggested buying a 3500 with the gears the OP wants already installed. Which no such thing exists.
So getting rid of his 2500 would gain him nothing except a rating.
No if the axles are different then the brakes are probably larger as well and that kills my theory. And if the OP fears the weight police then that kills my idea as well.

 

[mtofell]

Why does EVERY thread turn into a payload debate??????? We're talking gears here!!!! Stupid 2500/3500 argument has been beaten to death on this forum and EVERY other net forum. Go find a relevant thread to hash it out PLEASE!!!!!!

OP, I'd say it all comes down to what kind of driving you do. With your highway driving at 75 I'd probably go 4.56 with stock tires or 4.88 with slight up-size. I tow the exact 5th wheel with 3.73 and stock tires and have read these forums extensively. If/when I do the re-gear I'd probably go 4.56. That's a huge change from the stock 3.73. 4.88? Sure, that would be fine as well. I think it would be difficult to even tell the difference between the two.

The best tool I've found is an RPM calculator and playing around with my truck to replicate the RPMs at cruising speed so I know what I'd be in for.