Rear Axle Gear

In the 15 years I have followed the halt ton market, any given person seems to get the same unloaded fuel economy between the shortest and tallest gear ratios. Their driving style affects it compared to others. The 6+ gear transmissions have taken the axle ratio out of the acceleration/performance equation, but but I still say 3.73. No reason not to. I also recommend the max trailer towing package for the extra payload which means forces the 3.73 gear anyway.

I have been told that the lower geared, bigger tired F-150 really suffers on gas mileage around town and towing.

I commute daily 18 miles each way and usually add 6-12 miles a day if I go out to lunch or have a client appointment and avg 17 mpg between gas stops. I've got the 3.73's and 20" wheels.. I'm mostly in rush hour traffic and avg maybe 30 mph over a 2 week period.

I just did a 210 mile straight hwy run to Sequim from Puyallup WA and back where my folks live and got a solid 22 mpg on the computer.. Yes, I know everyone says the computer is always wrong, but mine is pretty darn close and I'm rounding DOWN anyway... ;)

A lot will depend on how your drive it too of course.. Keep in those turbos and it'll suck the gas! I do get into those turbos a bit too, but I can also drive like Grandpa too... :)

I think I get better mpg with the 3.73's on my commute because of how slow my avg mph end up being.. Anyway, it's all speculative and get what you feel will work best for you and go from there... Folks are happy with 3.15 geared trucks, so there you go! :)

Mitch

I tow a 26 ft. TT with an F-150 EcoBoost and 3.55 gear with no problems using the tow haul feature.

I have been told that the lower geared, bigger tired F-150 really suffers on gas mileage around town and towing.

I get 19 to 20 mpg with no TT on the flat at 65 mph and 10 mph on the flat towing the TT at 60 mph.

Since I use my truck every day, non-towing mileage in important.

I got lucky and found my brand new Max Tow F150 sitting in the back lot with the USED trucks and got it for $10k under sticker... :)



I like the 3.73's with the factory 20" wheels.. It runs in 6th gear most of the time on the hwy towing my #5000 TT. Not towing, it gets me anywhere between 21 and 23 mpg going 60-65 mph. Going 70 mph, it's running around 1800 rpms.

I've not taken it on a road trip where the speed limit is 70 while not towing, so not sure how it'll do at that speed? Towing I get around 10-11 mpg.

The pull the Eco has with the 3.73's is really strong.. I love it! :)

Good luck with the search!

Mitch

I have a 2012 f150 ecoboost supercrew with 3.73 gears. It does very well and you may want to consider that gearing for future possibility of a larger trailer if you plan to keep the truck a long time as I do. You may have to order it as the above poster is correct in that dealers do not keep many with that gearing on the lot. I ordered mine mainly for the 36 gal. fuel tank and it is only available with 4X4 package. Full towing package is also very nice with the tow mirrors, trailer brake, and upgraded radiator and tranny cooler.

In fact. The towing package will come with many rear gears, including a 3.15.
However. For a 5000lb loaded TT the 3.55s you are thinking about will do just great. An 3.5 EcoBoost with the 3.55s is rated to tow from 7300lb in a super crew 4x4 to 9800lbs in a 4x2.
Of course is does depend on the GCVWR package you have, which depends on the GVWR package you have. To get the 9800lb tow cap. you will need a minimum GCVWR of 15000lb. To get that you will need a minimum GVWR package of 7650lbs.

However a 13400lb GCVWR package gets you 7500lbs of tow capacity. which is enough to tow your 5000lb TT.

so you see. It really does matter what rear gear you get. A 3.73 rear will get you to 11,300lb of towing capacity. But it is highly doubtful you will ever find one of those on a dealer lot, as they get the higher gears to promote MPG to buyers that don't do their homework.

Hi,

It really does not matter to much what the rear axle ratio is. You will rarely be in drive, and more often will be in overdrive while on the freeway. Your throttle position and the engine management system will determine what gear the transmission will be in, and what RPM the engine will run for a given throttle position.

Say that you are pushing really hard on the throttle, the engine will rev up, and it will stay in the lower gears a longer time, so that the engine can produce maximum power at that higher RPM! If towing, then it will run in a slightly lower gear and then run at a higher engine RPM going up the hills.

While driving solo, then the engine management will try to shift into the highest gear, to get the best mileage!.

What options I would be looking at would be more along the lines of maximum cargo rating, so that the trailer weight, and cargo that you want to bring along will not cause you to exceed it's GVWR capacity. Better to buy something a little higher capacity now, then need to trade in the truck in a couple of years when you want a heavier trailer!

You will be limited to almost any 10,000 pound travel trailer, but the F-150's limited 2,000 cargo rating, and the need to carry some passengers will limit the truck to a very few very lightweight fifth wheels. So a 8,000 pound fifth wheel might have a 2,000 pound loaded pin weight, and that would not leave capacity to carry any passengers without going way over the GVWR.

At least the aluminum body F-150 in 2015 will have a higher cargo rating just because the curb weight will be less. So mileage should be better too!

Fred.

I think if you get the trailer tow package (good idea), with the towing mirrors, trailer ready wiring, and integrated brake control, it will come with 3.73 gearing.

I think 3.73 would be a good choice, and work great with the 6-speed transmission.

Jerry