Hey it's been a while since I have posted in here, and my question may be a moot point but...
2016 F150 SCAB, 2.7L, my first 25K miles I was averaging about 21.8MPG combined HWY and city. After that I swapped out the factory Goodyear Highway tires for some (same size) Falken Wildpeak AT3W tires which were a more aggressive tread, and my MPG seemed to drop to about 21.2 but I also think in that time period I swapped out my factory muffler for a Magnaflow knockoff straight through muffler and put a Spectre cold air filter and box in my truck.
I have not changed the ride height of the truck through all this... I now have a cap on the truck, have swapped out the front factory bumper for an aftermarket steel one, heavy duty, and that warranted removing the lower valance as well. Still with the Fsalken my MPG dropped to about 20.8.
Now last fall I put some Nitto Ridge Grapplers on, and I upsized to a 285/70-17 so I expected a little change in MPG but my avergae now is about 19.1-19.5 at best but I know I haven't recalibrated the trucks computer to accomodate for tire size changes...

so With all the changes on the truck, I am trying to figure out what my actual MPG is, I know the changes from a Highway tire to a aggresive tread will reduce some MPG, so I figured that is what accounted for the initial drop with the goodyear to the Falkens. Adding weight to the truck from the cap and front bumper, and removing the front air dam didn't help with MPG, but it seemed like going from the 265/70 to the 285/70 I dropped more MPG than expected.

If I do the calculations correct, the 285 is a 3.3% larger tire than the 265, so the expected change in speedometer speed and MPG should be pretty relative, but the drop in fuel economy is more like 7.5% from the tire change- or maybe as my truck is racking up the Miles, I am starting to get buildup on my valves and that is a more contributing factor?

I was all set to get Seafoam spray and do a clean through the intake charge tube, but I read a lot of people saying that you should not do that in these engines as the crud runs through the exhaust impellers on the turbo.

So I guess a couple questions...
1) what have others experienced with tire changes?
2) if I recalc my tire size in the computer how much do you think it will change the calculated MPG in the computer?
3) is my drop in MPG just getting worse from added weight/reduced aerodynamics?
4) what have you guys seen as far as changes in MPG with mods on your 2.7 motors?

I have 88K on it now, and I do not use a drop of oil between changes, I have always used good quality synthetic since the first oil change, and I buy gas primarily from the same gas station every time I fill up, it is a wholesale club that I have been going to for years.

 

I haven't changed the tires from what came on it from the factory in my last 2 F150's, so this might not help much. But on previous trucks, going to a more aggressive and heavier LT truck tire from the P rated factory tires pretty much cost me close to 2 mpg. Both city and highway. I am assuming it was due to them being considerably heavier, and having more rolling resistance than the stock tires.

 

2) MPG will go up about 3% because your actual mileage will go up about 3%

3) It's added weight, reduced aerodynamics, and increased rolling resistance. I presume the 'highway tires' were p-metric, and you put on LT tires.

 

Going from a highway tire to an off-road tire, some drop in mpg due to tread pattern causing more resistance.
Going from a lighter to a heavier tire, some drop in mpg due to additional energy required to turn them.
Going from a shorter to a taller tire, some change in mpg due to change in effective gear ratio.
Going from a narrower to a wider tire, some drop in mpg due to additional resistance.
Heavy bumper / cap equal weight equals a drop in mpg.
No air dam, probably an impact to aerodynamics, likely some drop in mpg (up for debate on how much).

.......buildup on your valves......unless you use super cheap low detergent fuel....highly unlikely.

 

I have the same year, model, and engine. I replaced the OEM Goodyear's with LT tires which were 14 lbs heavier each. I lost about 2 mpg. I then stopped using 87 octane and switched to Sunoco 93 and I got about 1 mpg back.
The heavier tires on the back necessitated better shocks and I went with Fox.

 

My math says 20.18 mpg. Not too many years ago if you got that mpg in that much truck with all that equipment, you'd probably get arrested for indecent exposure every time you stopped to get gas because of the boner.

 

ha ha ha!!! Yes, several years back(before I got my truck) I kept saying why is it so hard to get more than 20mpg out of a truck?

I guess guys like us like big motors, big tires, big bumpers, and usually that won’t give you any kind of mileage.

i haven’t decided if I want to use ForScan to fix my tire diameter yet- I know it’s a weird number you have to put in there, I haven’t taken time to look for the correct one yet.

im still super happy with the truck, I came from an 04 avalanche and that barely got about 15 when babying it, usually 13 hard driving, and about 8 when towing. I can still get my F150 about to 20+ on the mis-calibrated odometer on the highway. Cruising around 60 or less seems to do amazing.

 

I have a 2019 5.0 screw with a level and raptor takeoffs. I was getting a hand calculated 17ish mpg city on the stock suspension and tires. With my level and raptor takeoffs I’m getting 15.5 city. Haven’t done a highway trip but was getting 20 highway before, so I’d expect 18.5 highway or so. Never got the 22 ford advertised, but I’m not doing 60 either. I did recalibrate the speedo about 2 weeks after I had the upgrade done and did see an improvement in what the lie-o-meter showed, but hadn’t run a full tank to do the math.

In my old 2007 dodge with the 5.7, I was all stock except for AT tires in the stock size, but they only weighed like 2lbs more than stock. If I got 15mpg on a highway trip it was a great day and typically got 12 city. So to get 15.5-16 city on a leveled truck with 35s I’m ecstatic.

 

Most of the time I do a lift , gearing, wheels and tires. I always affect the mileage. In 2012 I bought a super duty and all I did was change to heavier tires 35" on the stock rim my truck got 2 miles to the gal less. Just from the tires. On my 2016 F 150 (5.0) I put a 4" suspension lift, re-gear, rims and 35" tires,Borla exhaust, I get 16 mpg on the freeway and 13 in stop and go traffic. I live in California and if I could put a good tune on my truck I could get back a couple of MPG but NO not in California.
I am happy with my truck the loss of MPG is worth the look and my truck handles better than it did when stock. I really enjoy driving my truck. 66,000 miles so far.

 

Very nice looking truck! I wish I would have sprung the extra $1k for a better looking topper. I bought a ATC and while it's not the old aluminum topper with crank windows, it's a lot less "automotive" looking than the Snugtop, ARE, and LUNDs. The rear of mine is more squared off instead of rounded to match the contours of the truck. Good choice.