[rcooley]

Hi All,

I’m trying to decide on the best gears for my future purchase. I’m trying to see how big of a difference the gears make on the gas millage. That always seems to be the information people leave out of their MPG reports.

Also I have read several threads talking about towing more than the truck is rated for but they typically leave out what gears they have.

To me the gears are a huge part of evaluating the MPG and the towing ability.
Can some of you guys please clue me in on your experience with these two topics and let me know what gears you have?

Thanks!

 

[mattyj724]

i have limited experiance with towing above the rating. I have the 4x4 3.55 gears and it hauls my 3K LBS boat just fine. Cant tell its there.

3.55= better gas milage less pulling power
3.92=better pulling less MPG.

If you plan on towing 9k on a regular basis then get the 3.92. honestly at that weight you wont be getting great milage anyway. I tow once a month or 3 time if i am lake happy during the summer. 3.55 makes sense. I use the truck as a daily driver most of the time.

 

[Katoom250SX]

Just my .02. I ordered 3.55. I do 85% driving and tow the occasional "normal" trailer (utility trailer with dirtbikes or a quad, 25' camper, 19' boat) a total of 15 to 20 times a year combined. Nothing I have is over 5500 lbs. I went with the 3.55s based on the percentage of time I don't trailer anything. The question you need to ask yourself is how often and how heavy will you be? I've read threads were guys only lose 1 mpg hwy with the 3.92s. Good luck!

 

[10%More]

You are getting some good advice. Listen. My choice was 3:55's. Not disappointed as I haven't towed above 6,000 lbs and doubt I will ever get above 8K. No issues.

Oh - no "gas" mileage on a diesel. Now start to think "fuel" mileage and "fuel" stop.

 

[Katoom250SX]

A buddy of mine was giving me crap about the lower tow capacity, & my question to him was "how many times since you have owned your truck (3+ years) have you been over even 75% of the 10,400 lb tow capacity"?....His response, "probably never". My point exactly. This is why the ED is such a beautiful thing.....A family vehicle with a bed and hitch. I do way too much non towing / hauling to deal with 16-17 mpg! It all comes down to personal needs.

 

[rcooley]

Thanks for all of your replies!!

So here is my issue,
I have a 5500 pound tractor (including attachments) and a 2500 pound trailer so I will be pushing the upper limit of it's rating. That being said, I'll probably tow it less than 5 times a year. Typical trip would be about an hour with mostly expressway driving. Possibly a 5 hour trip once every couple years.

Other than that and towing a couple 4 wheeler's the truck will be a daily driver for me. That's my dilemma, sacrifice the better mileage day to day so that I can tow a little easier a few times a year.

The laramie limited towing capacity is 7350 with 3.55 gears and 8350 with 3.92 gears

What would you do 3.55 or 3.92?

 

[Katoom250SX]

Oh boy....you are right on the bubble. Technically you would be over those few times a year, but I'm sure the 3.55s would work. Really with that weight I'd be more concerned with suspension sag. I'm not towing heavy, but for the price I've already purchased a set of air lift air bags. They are supposed to be good for a 1000 lbs. They help with sag, bounce, and some say sway. I've never used em but for under 100 bucks I figured it would be a nice add on. I'd like to hear someone chime in on difference in mpg. If it's minimal maybe 3.92s won't be a bad fit for you since you actually pull something that's heavy. Do the math once. Figure 1 mpg less over say 50000 miles and see what the 3.92s would actually cost you. If it's not much it may be a good option for you.

 

[Katoom250SX]

I just did a quick math work up....24 mpg average over 50k miles @ 3.69 a gal compared to 25 mpg is about a 300$ difference over those miles. If it's only 1mpg, I'd say go with 3.92s. But again I do not know if that is an accurate estimation in fuel economy.

 

[Katoom250SX]

Transmission section. ...axle ratio vs. Mpg....Some additional information there. It's like anything else. Many different opinions and at the end of the day you are just as confused as you were prior to asking the question. Ha. It sucks I know! In my opinion if it's a minimal gap ( 1 mpg or less) go with 3.92s. Just remember the more fuel costs the more that 1mpg loss will cost you. Really tho 300 bucks over 50k miles @ 3.69 isn't too bad.

 

[DIESELBLOCK]

Go with the 3.92's... The 8 speed has high enough gearing and overdrives to make up for it. 3.92's will give you better all around performance

 

[DIESELBLOCK]

Oh boy....you are right on the bubble. Technically you would be over those few times a year, but I'm sure the 3.55s would work. Really with that weight I'd be more concerned with suspension sag. I'm not towing heavy, but for the price I've already purchased a set of air lift air bags. They are supposed to be good for a 1000 lbs. They help with sag, bounce, and some say sway. I've never used em but for under 100 bucks I figured it would be a nice add on. I'd like to hear someone chime in on difference in mpg. If it's minimal maybe 3.92s won't be a bad fit for you since you actually pull something that's heavy. Do the math once. Figure 1 mpg less over say 50000 miles and see what the 3.92s would actually cost you. If it's not much it may be a good option for you.

Can't he just get factory air suspension?

 

[Boocoodinkydow]

If you live in a relatively level terrain & are towing that infrequently, I'd definitely go with 3.55 & add air suspension. The torque curve of the ed is a great match for 3.55's. I use mine primarily for long trips & love the sweet spot of peak torque falling at about 75mph. Fwiw I've had 1600# in the bed with 2 big guys, a full tank & a heavy (about 200#) bed cover and the air suspension leveled it out perfectly without a hiccup.

 

[DIESELBLOCK]

I think 3.92 is the way to go for sure.

 

[Katoom250SX]

Can't he just get factory air suspension?

Yes he absolutely could.....for a additional $ 1600.00. Or he could save $ 1520.00 & add a air lift kit as I am. And if he wanted an on board compressor for the kit it would only be 250 more. Don't get me wrong, I think the air suspension is cool, but it is the only option I elected to not get.

 

[DIESELBLOCK]

Yes he absolutely could.....for a additional $ 1600.00. Or he could save $ 1520.00 & add a air lift kit as I am. And if he wanted an on board compressor for the kit it would only be 250 more. Don't get me wrong, I think the air suspension is cool, but it is the only option I elected to not get.

cool, any pics of your setup?

 

[Katoom250SX]

cool, any pics of your setup?

Air lift 60818 is the kit. A web search will give you all of the specifics. I haven't taken delivery of my truck yet but I have the above listed kit sitting on my workbench ready for install. I do not have the on board compressor and don't plan to add it. In just a few minutes I can add or subtract air just the same as a tire. Msrp if I recall is around 135.00 but I've seen them under 80.00 with free shipping. Air lift is a very reputable company and the kit has a lifetime warranty!

 

[ED_Lover]

It seems to me the final drive gear ratio is pretty unimportant when you consider the transmission has 8 gears to choose from.

And the tow rating difference is bogus as the only difference is you might be sitting in 5th gear towing 9k pounds with 3.55s instead of 6th gear with 3.92s. It's marketing nonsense more than anything.

 

[hoogie514]

3.92 all day long

Grab the 3.92, you won't notice a difference in fuel economy unless your going over 50mph but you will have the higher tow rating and a bit more power to the ground. About 200rpm higher cruising at highway speeds....

 

[ahab]

3.55 vs 3.92

I went through this same process, prior to ordering and receiving my 2015 outdoorsman. I ultimately decided on the 3.55, as I sometimes tow, but sometimes do not, and desired the lower rpm's at highway speed with the 3.55.
With the tow/haul engaged on the transmission, it is really good at keeping you in a good rpm when towing. If towing a heavy trailer, it may just keep in 7th gear. Plus, and I did not realize this until actually driving and towing with the truck, you can downshift the transmission with a button on the steering wheel. It will stay there in that lower gear. That is, if you are towing heavy at 55 or 60 mph, you can just keep in a lower gear. The transmission is excellent and very flexible.

 

[Mopar1]

I have 355's have towed 14,000#'s on 21' trailer several times never had problem