Hi all, First post here. Been lurking a while and just pulled the trigger on a 23 XLT scab 302a build in avalanche gray. Thanks for all the good information on this forum.
I’m planning a few mods right of the bat, namely a 2” level and 33” tires. Still undecided if I’ll keep the factory 18” wheels or get aftermarket 20”. Right now my order has the 3:31 non slip rear end and trailer tow package.
I’ve done some reading here about which rear gear ratio to get and I’ve come away a little overwhelmed. Most posts say to go with a 3:55 ratio if running bigger tires or towing. What they don’t mention is how big of tires and how much you’re towing. Fuel economy is a consideration so I don’t plan to go with to big of a tire or too aggressive of a tread. Thinking Yokohama Geolander AT or Falken Wildpeak H/T02. No poke, stock offset, 33”, no more than 34” tires is what I’ll be using and don’t plan to tow over 5,000 lbs.
Is there anyone with a similar set up on a 14 gen or who can weight in on if the 3:31 will work or if I’m better off changing my order to the 3:55?

 

If you are thinking of increasing the diameter of the wheel and tire combo, you should immediately modify your order to get the factory 3.73 ratio. Way cheaper than after market, plus unless you don't like them, look at the sport 20 inch wheels that Ford offers.

Plenty of discussion on lifts, including problems people have had with some of them.

 

Which engine are you getting? The ecoboost engines are more tolerant of big tires as they make more low end grunt. The 5.0 is better with 3.73 gears if you plan on going to bigger tires.


FYI the ratios you referenced are 3.31:1 and 3.55:1. It’s a common typo to say 3:31 or 3:55.

 

3.73:1 is going to be your best bet when going larger tires in 100% of situations. With the 10-speed transmission, 3.73 gears aren't a negative at all either.

 

Agree, if you’ll be towing the minimum would be 3:55. This way you’ll have a good all around ratio. Decent towing and fuel mileage. 3:73 is definitely the bee’s knee’s for rock climbing and towing, but fuel economy will suffer. This however, can partially be recovered with a light P metric tire that’s still acceptable for towing ( seeing how you haven’t opted for the max trailer tow pkg (or the tow mirrors))

lots to consider when building a truck. I remember when I ordered my 16’. I spent 3 days combing over build weights of each component; as I wanted a mid trim lariat with maximum payload. You’d be be surprised at the weight saving on just non LT tires and non folding steps and no moonroof etc;

good luck.

 

Thanks for the inputs so far. Yes, several things to consider for a newb when deviating from stock wheels, tires and suspension. I like the stance of a little bigger tire and 2” level but at this point wondering if it’s worth it. May just go with factory 20’s and call it a day.
Will be getting the 3.5 eco boost.

 

Well, the truck comes stock with darn near 33's, so replacing it with one of nearly the same does not justify a gear swap.

Another thing to consider, the 10 speed and 3.31 gear is similar to the 'old school' 6 speed 3.55 rear. The trans in geared lower internally, therefore the higher gear is very similar to before.

Add in other thoughts as mentioned above like a greater than 33" or towing anything.
I'd go so far as to say if you live in a hilly environment the gear choice may be a consideration.
I had a 6-speed 3.55 and there is no way I would want anything lower to drive around in the hills. Every time the traffic light turns green or I leave a stop sign, I'm pushing over 5,000lbs up a hill. Not always, and never too steep but as many times in one trip while cruise through town, the high gear ratio would suck.

Being "enduro", I am guessing dirt bike. Do you like a large rear sprocket or small? If you mean you race downhill mountain bikes then you don't understand gear ratios anyway. haha

I think you could compromise and change the order to 3.55 from 3.31 with the 10-speed. The 3.73 is a good option but that could be a little too low for gas mileage. However -if you drive mostly in town type of scenarios, the 3.73 with a larger tire will be nice to get the brick moving from a dead stop -even more so if you live in hills. The lower gear like a 3.73 and the 10-speed on the highway is probably okay (I don't have experience), but they have 3 overdrive gears now, with 10th being like 0.7:1 or something like that.... higher than most traditional overdrive gears. I think in the 90's, the AOD was .71 or .74:1. That makes me think the 10 speed is in the 0.6's for 10th. You'll lose some RPM in that high gear even with the 3.73.

My goal here was to shed light on just how confusing gear ratios are. If you are sticking to 33's (virtually stock) and drive highway without hills, the 3.31 is fine. If any of my scenarios above are true, a 3.55 or 3.73 will treat you okay and any fuel loss will be minimal(ish). It will be more fun to drive.... especially if you got the V8. I'd say for towing 5,000lbs with 34" tires in V8 you need 3.73's (if available)

 

Thanks for the reply. Yep, I’m a dirtdike rider so I understand gear ratios. No experience with the F150 though. I drive a lot so I’m trying to tweak the most mpg’s I can get while still enjoying the look of my truck.

 

I had 3.55's in my 2018 2.7L, and for daily driving, it was perfect. For pulling a trailer though, even occasionally and even with towing a simple U-Haul motorcycle trailer, it would chase gears from 8-10th gear on the highway... Easy enough to lock out those gears, but then you're also hurting your fuel economy. With 3.73's (which is the ONLY option on a Powerboost, just for note) you may be SLIGHTLY worse on fuel economy on day-to-day driving, but towing you will likely be able to run a gear up from what a 3.31 (or maybe a 3.55) may be comfortable at, which should help towing economy a bit.

I can also speak for 3.31's on the 2015 5.0 and towing a 28' toy hauler traveling around doing ADV riding with my dad... The 2015 had the 6-speed transmission, but the 5.0 and 3.31's wouldn't run higher than 3rd gear for the majority of the trip when towing that trailer. This was my dad's truck, but he and I switched off driving, so I've got experience driving the truck as well.

For me at this point, from personal experience, I'll be 100% on ordering 3.73's if I EVER plan to tow (or wanted to upgrade tire size). That said, I've already had my truck ordered for closing on a year, and being a Powerboost it does indeed have 3.73's in it... Now just to wait for my truck to get built this week, and hope for no delays...

 

which engine? I have the 5.0 with the 3.31 rear end and even going from the stock ~31” tires on steelies to some take-offs that are like a 32.4” it has to down shift more on hills. I wouldn’t even do 33”s without 3.55s. I already know I’m going to have to swap gears if I keep this truck a while as I’ll inevitably lift it. I have a coworker with the 3.5 and 3.55s on 35”s and it pulls just fine, but I wish I’d gotten the heavy tow package to get the 3.73.