zstaheli

I have a 1996 Dodge Ram 3500 dually. It’s got the nv4500 and the bomb proof 4.10’s. The most I ever tow is around 14,000 pounds with my toy hauler fully loaded with liquids and the rzr and bikes inside. It’s a triple axle tongue pull as well lol. So what im getting to is that my majority of driving is around town amd on the freeway. I understand that the 4.10 is best for around town driving but when I get on the freeway it’s a dog. 5th gear at 70 mph I’m at 2,300rpms!! This is ridiculous in my opinion. So I want to regear to a 3.53 or a 3.73 so I can lower my Rpms while gaining speed and maybe a little more fuel mileage on the freeway. Are those two gearing ratios going to hold up to 2-3 hours of hauling 14,000lbs? Is there any price difference? Any info will help. Also it would be nice to keep the 4.10 so if anyone knows how to get more speed with lower rpms that would also help.
#10 fuel plate
star wheel turned up two turns
4 inch turbo back exhaust

oliver foster

Cheapest and fastest way to get better highway speeds at lower RPM is to install bigger tires and keep the 4.10s

zstaheli

what tire size do you suggest? Right now I have 235/75/16. And what kind of speed gains are we talking?

oliver foster

The RPM drop will vary in ratio to the tire size you go up.
There are tire size, gear ratio, speed ratio calculator pages on the web.
Do a search and see what make sense for you.

I run 37s on my '85 crew cab with the 4.10 ratio and it is very close to running stock tires and 3.54 gearing.
That would be a little extreme for a dually tow rig, but a few sizes up for the tires might be a perfect, cheap and easy solution.
You will want to stay with a tall and narrow tire so you don't end up with rubbing problems on the rear dually tires.

texasprd

You should also consider that running taller tires or "longer" gears will make life harder on the driveline when trying to take that trailer up hills or accelerate. I do understand why you want to do this - just cautioning that those factors need to be considered when it comes to deciding how much of a change to make.

oliver foster

That is part of the reason I recommend a mild change with a slightly taller tires rather than going to 3.54s.
I run 3.54 gears and stock tires on my '95 dually, but I don't tow more that 10,000#s. That is a big swap I know, as that truck used to have 4.10s.

zstaheli

I’m definitely going to get a bigger tire size no matter what I do. Also money isn’t an issue as of now. I feel like a 3.73 would be a good swap. I drive the highway 3-4 times a week and I’m more worried about speed than I am towing capability. I’ve also been thinking about putting a nv5600 tranny in it later on down the road. What kind of rpm ranges are we talking there? Any info is greatly appreciated.

oliver foster

Installing a NV-5600 to lower RPMs on the highway, is a common mis-conception.
The 4th gear in a 5 speed is 1:1.
The 5th gear in a 6 speed is 1:1 as well
The final over drive ratio on both transmission is very close, so you will gain more of an RPM drop with a one size up tire swap than you will from installing a NV-5600. The benefit of the 6 speed is closer ratios in the lower gears that helps tow really heavy trailers on steep terrain at varying speeds, like backroads.

When I swapped my dually to 3.54 from 4.10s, I swapped axles, rather than re-gearing the axles I had. I then sold the 4.10 geared axles.

u2slow

Do the tires first. Then do some test hauls.

Any change to your final drive - like larger tires or taller gears - is going to drive up your EGTs.