Hello all. Im new on the board, but have been reading it for a while. I finally bought a 2001 Dodge 2500 4X4 Cummins diesel with the 6-speed manual. I love the way it rides and all the power it has. The only thing I will like to do is reduce the RPMs Im turning when Im at 65-70 mph. I am getting about 2300 RPM at 70mphs. Feel like it should not be that high so I guess I must have the 4.10 gears. Ideally I would rather go down to 3.73 or lower, but I have heard is very expensive to get this done by replacing the gears since I got the 4X4. I am burning about 17-18 mpgs at that speed and I think that If I can reduce the RPMs, my MPGs will come down too.





I am running 265/75 X16 tires now. I have heard that going with taller tires (and I do have plenty of space for them) could get me the equivalent of a 3.73 or maybe even lower. I am towing a 6k rig now.





I will like to hear inputs on which size of tires will give me what Im looking for, and if there are any other considerations when doing this since the speedometer/odometer and maybe some other sensor/gauge may be misreading. Can the dealer do something on the computer to compensate? Please, also let me know how much will it cost to get the gears replaced front and back.

Sounds like 4.10s to me. You won't get much better with a 24 valve with either gear ratios. The older 12 valve Cummins got better fuel mileage. All of this is EPA related. Regearing might cost more up front, but I wouldn't get too much higher for tires since you're pulling with it. Note that you might get better mpg with 4.10s while towing. Remember, even if you get better fuel mileage with higher gears, you could buy alot of fuel for the price of the gearing. As for speedo correction, dealer can do it, or you can buy a correction box.

I have the same set up and run 2300 rpms at 70mph with 4.10 gears . If you go with a 285/75X16 it will be equal too 3.73s gear.

im running 35x12.50-16.5s bfg muds and im at about 2100-2200 at 70, and with my lead foot i get about 300miles to a tank

Wow, and I thought my 575 was bad... :o)

Ive run 3.55s and I like em. If you tow real heavy and you want to leave it stock. Keep the 4.10s. Ive run everything from 32s, 33s, 34s, and 35s. The bigger you go the more lag you get on the bottom. But of course you have better gears for bigger tires. I like the way the 33s ride.

I have the 4:10s and run 63 mph at 2000 rpms.. gear vendors makes an overdrive for it...This will reduce the rpms to about 1600 at 70 mph...

I have the 4:10s and run 63 mph at 2000 rpms.. gear vendors makes an overdrive for it...This will reduce the rpms to about 1600 at 70 mph...


Hey falcondan95705, do you have any more info on the "overdrive" gear? I have a 6 speed and would love to get something like this for mine. I don't tow but spend a few thousand miles a month on the interstate between 75 and 90.

I have a 2001, 6sp,355 rear. At 70 mph its at 2000rpms, ingage the gear vendors overdrive and it drops to 1500. Much, much quieter!

only worry I have is if any one else drives the truck that kows no better and they try to engage this while in 4 wheel drive.... talk about ripping apart a drivetrain..... or is this overdrive a magical beast that changes the ration to all four corners?

Mine is a 2WD, but they do make them for 4WD

I always find the solution is to just not let anyone else drive the truck! http://www.dieselplace.com/forum/smileys/Big Smile.gif In the rare instance that someone else has to drive any of my vehicles (none of which are stock), I give them a quick lecture on what to look out for. Unless you're in a situation where your vehicle gets used often by others, it only takes a second to say "See that button? DON'T PUSH IT!"

Here's the Gear Vendors link:http://www.gearvendors.com/


It is a heavy duty unit with a heavy duty price. You can buy a lot of fuel for the cost of it...then again you can buy a lot of gasoline for the cost of up-grading to a diesel.http://www.dieselplace.com/forum/smileys/Embarrased.gif


I'm not sure that there are applications for the late model Dodges...better call.