I'd be first to suggest a low rolling resistance tire, having seen them in action in the car industry, however with trucks, most need a tire that can handle a load and perform in adverse environments.

 

I believe the Michelin Latitudes qualify as a LRR tire as well.

 

I think something is wrong with mine. I've never towed a thing, I'm getting about 11 mpg or 21 L/100km. I have a 2014 3.5L w/ the 3.73 gears and tow package, supercrew 6.5' box. Its got a 2" leveling kit and some knobby 295's as well but my MPG shouldn't be anywhere near this low. This is also about 80% hwy driving.

Maybe it just isn't broken in yet? It has been getting better, it started at 9.5 mpg when I picked it up.

 

A few things to remember, if you drive the freeway often, every time you punch it to get up to speed you lower your gas mileage. If you drive the freeway often for relatively short periods then it really kills you mileage because your economy doesn't have time to recoup the hit from punching it. I've noticed going faster than 70 mph starts to really lower you economy. Your mileage should get a bit better as it breaks in. The mpg is very dependent on how you drive. If you are a red light racer your mileage will be horrible. If you drive a little more like grandpa your mileage will be much better.

 

Plus he is 4wd with 3.73s, long bed, level kit, big tires which = crap fuel mileage

 

I notice my "instant" gauge shows my MPG at "0" when I am at idle in the drive way or at a light. The L/100km is maxed out at 40 when I am at idle too. What do you guys show when idling?

 

I believe those knobby 295s are your culprit. I went from P235/55R16 to 265/65R17 and I lost about 1.2-1.5mpg across the board. My truck feels heavier off the line, too.

 

0 at idling and at a stop light on my truck also

 

I'm sure driving habits are as much as a factor as the mods. Heck, my F-350 with a level kit and 325/60/18's get's better MPG's than this guy, way better.

Maybe I should just stick with my diesel.

 

Just my 2 cents, our eco started life at 9.8 mpg average, motor replaced after a war with a useless dealer in cedar city utah@ about 2000 mile due to very loud ticking and knocking that they said was normal. About 9000 mile on that motor we now see an amazing unbelievable 14.5 average. I drive this like an old man (oh I am old) I use higher 91 octane fuel and the mpg still sucks. I would be getting rid of this p.o.s. but as said I 'm old retired and can't afford the loss of trading it in.So i'm stuck with it and ford is useless at figuring it out. And yes I am a disgruntled owner.

 

Of course you're a 0 MPGs when the tires aren't rolling. You are burning fuel but going no where, this is the worst possible mileage you can get. If you were full throttle you would be getting better mileage because you would be going somewhere. The gauge maxes out when you let off the gas and coast because you are moving but using little to no fuel.

Simply put, the gauge shows you how far you get from the fuel you are using not the amount of fuel being used.

 

Good point on the gauge, that makes perfect sense. I guess I wasn't thinking too hard about it!
I'm still not sold on the idea that the small mods I have made and my driving habits give me such a low mpg. I have been driving it as fuel efficiently as I can, I swear that my eyes are on the "instant mpg" gauge more than the road. I have friends with the same engine that are getting way better fuel mileage than I am. Also way better with the 5.0l engine in the same truck.
My last 3 trucks were a Chev 2008 3/4 ton 6.0L V-8 4x4, a Chev 2010 1-ton Duramax 4x4 and a 2011 F-350 6.4 powerstroke 4x4 and they have all had way better mileage. All had leveling kits and either Toyo M/T's or Wrangler Duratracs too.
I'm almost convinced there is something wrong with it and will probably be taking it in to the dealer soon.

 

When you added the taller tires did you correct your PCM to account for them? If not all of your numbers are off.

Secondly, compare the weight of one of your new tires to the factory ones then multiply by 4. Heavy tires kill mileage, there's no two ways about it. When you say freeway driving what speed are you going? Set the cruise to 65MPH and go for 10 miles. Then bump it up to 72 or so then go for 80, each time going about 10 miles and see what happens. I think the results will surprise you.