Had to make an I-5 freeway run this weekend to the Portland airport. 185 miles round trip. About 1.5 hrs each way.
My truck: 2016 6.2 3.73 CCSB 4x4 all stock running 275/70/18 bfg at 70 psi. The tires measure at 32.5" tall.
Drove up at 3:30 am Friday 75mph, 1950 rpms, 55 deg, 6th gear, no traffic, no stop lights, dry roads, just cruised. Reset my mpg at my house. When I parked at airport, it read 12.9.

Drove home Sunday night at 7:30, 85 deg, 75mph, 2500 rpms, 5th gear, some traffic, some lights, ran the AC the whole way. Did my return trip in 5th gear, which is the mathematical equal to 6th gear and 4.80 gears on my truck. Reset my mpgs when I left the parking lot, at my driveway it read 13.5.

This section of I-5 is flat, and I gain less than 100' of elevation returning home.
I post this info because since owning my truck, I have been tracking mpgs. I have read the false notion that a 4.30 gear truck will get worse mpgs than the 3.73. Well it is not true for a 4x4 running a tire larger than stock 31.5's.

 

Weird. My mileage improves with my 3.73 gearing when I allow sixth gear. So much so I'll gain miles to empty on the computer while driving after unlocking sixth.

 

Headwind or Tailwind can make a big difference, I see it all the time on my instant readout on my ScanGauge.

 

My 5th gear numbers are closer to 1mpg better per avg tank when I do my normal hwy commute at 55-60mph. I dont have an instant read out so I use calculated numbers or reset my computer when I head out on a drive.

 

I live about 12 miles of highway out of town where you can average 45-60mph depending on the traffic and if I drive around a bunch with sixth locked out like I often do and then do a trip to town and allow sixth I'll usually gain miles to empty by the time I get home. I don't calculate anything myself. Lol. Quite scientific I know.

 

an aerodynamic brick will always be an aerodynamic brick. big flat front.... and poor design on the back for air flow...
NO underbody decking.

mirrors stick out like plywood.

shall I continue.

but still better then my 1965 Impala SS 409, 4 speed with 4:11 on 15 inch wheels and weighting 3500 pounds.. it gets 9 with just me in the car.

 

I'll try it with my ScanGauge on flat ground....when I remember and report back on the instant readout

 

I have a 2016 F250 6.2 4X4 supercab. I am looking at upgrading our travel trailer to a fifth wheel. I noticed on the Ford site my tow capacity for a fifth wheel goes from 12,000 to 15,000 with the 4.30 gears. I was wondering if I pay to change to the 4.30, how does that change my daily driving? I drive my truck empty 33 miles each way to work on a combination of highway and city with speed limits from 60 to 45 mph. I am not too concerned about the MPG.

 

Every post I have read over the past year where one changed to the 4.30 says it is the single best modification they have done. I have yet to find a 4.30 truck that gets any worse mpgs than my 3.73. Most do better, especially in town and towing. Even empty there is no negative I have found.

 

Thank you for the information. My wife want a fifth wheel that is a 12,000 dry. I barely understand towing, let alone explaining it to her. We live in Indiana where there are a few hills but nothing too big. I want to go down south or out west someday and fear hills bigger than here if I am pushing the weight capacity. $2000 to swap is a lot of money for just pulling a little bigger fifth wheel a few times a year. Who does the swapping of the gears? Dealer?

 

I would take it to a good reputable local 4wd shop. Some where that specializes in lifts on trucks and jeeps. They will have a lot more experience changing out gear sets than the dealer, and probably much cheaper. I've done it myself in my garage, with good success, but there is a lot to wrap your mind around. I did a lot of research. I maybe changing mine out in my truck in the future. My dad ordered a truck with 4.30's and I'm impressed. My 3.73's do everything I need to do right now, but future mods include bigger tires, so...

 

For a trailer that heavy in my opinion the single best mod would be trade it on a diesel. The 4.30s do help the 6.2 but it only goes so far. Parts and labor it can get over $2k to do both axles. Unless you buy the truck new with that ratio it will cost you.

 

12000 is at the top of the spectrum for a gas powered truck, to tow comfortably in today's world. People towed a lot more with 7.3 powerstrokes that didn't have nearly the hp, and just a little more torque. They just didn't have to turn the rpms that a lot of people are uncomfortable doing in a gas powered truck. They also didn't have this great transmission we have now. Unless I was planning on towing that load on a very regular basis down the interstate for a long distance, no way am I getting rid of my 6.2 for a diesel. The gear swap will cost you a little more than 2k, the diesel option alone is over 8k, not to mention the loss your taking on trading a 1 year old truck in. Gears and a 5star tune and I think you will be content. Most of your mountain pass speed limits are 50-55 or less anyway, not 70. I'm making this assumption based on my experience pulling 8500k threw the mountains with a stock ccsb with 3.73's. I know I would have been happy even if there had been a little more weight back there. Check out nitro gears, they sell the gears w/ install kits for 1300.

 

I agree, whole different ballgame with the newer trucks. Across the board pickups are able to pull more weight than ever. I don't ever care to be maxed out towing. I had a 2014 6.2, done 4.30 swaps, you name it. I got excellent trade for it and barely added any payment for the diesel. Each had good and bad but after towing with it the difference is huge. As far as gears, the Ford dealer will be the cheapest. On a new truck you don't need a whole rebuild kit.

 

Thank you everyone for the input. We thought about the diesel and I heard a lot of the pro and cons. The 8k more and the cost of maint. scared me off. I love my 6.2! I grossly under estimated how much these trailers really weigh. We have set a 10,000 lbs or less dry weight limit. We do mostly full hook up camping so we run tanks empty. We don't take much either. Just clothes, food, firewood and chairs. If I need a little more torque, I will upgrade the gears. Thank you again for all the help. I love this site. It has helped me a lot.