Dave1768

So I just bought my first f150 last week. It has 6in lift, 35x12.5 tires and 100k miles. I've been averaging 10mpg on the highway going about 75 with a light foot and city 12.5 with avg speed of 45 and very few stops, not really a city. I know I'm not gonna get good mpg but I thought it should be a little better than this. Is this normal and if not what could be the problem?

idrive

iTrader: (3)

Engine?

35" tires - 6" lift - 75 mph, all hurt mileage. Colder temps. Winter gas

100K miles. Have the plugs been changed? Tires inflated correctly? Are you carrying much weight in the truck?

Dave1768

5.0 been and it's been 70-80 degrees tires are inflated correctly and no extra weight in the truck at all. Checked one of the plugs they aren't terrible but I will be replacing them

marshallr

Has the speedo been calibrated for those tires? If not the speedo and your odometer are reading low. If your speedo said 75, you were really doing 82ish. If your odometer said you had driven 300 miles, you really drove almost 330 miles. When figuring fuel mileage you get a lower number than actual. Tires that big without re gearing really makes the engine have to work harder plus the lift increases wind resistance.

All things considered that sounds pretty normal. Slowing down to a 65 will probably give you 2 or more MPG's

Dave1768

It hasn't been calibrated but I've been using an app on my phone for speed. And what gears would you recommend?

Eduskator

More MPG in city than in highway? Something's not right.

Proper inflation is a must (and wheel alignment too!) All things that can cause additional friction or aero dynamism will affect your consumption.

However, 10-12 MPG for a F150 with a 6'' lift & 35s is not that bad. I would say it's within the average... EPA gas mileage for a 2014 5.0 4X4 is 14/19 I believe. Your city MPG is OK, but the highway MPG is really low. Even with a 6'' lift and 35s, it shouldn't be lower than your city MPG, it's illogic.

idrive

iTrader: (3)

Yes but if you look at his city driving it's probably the most ideal of conditions.

"with avg speed of 45 and very few stops, not really a city"

lutter5-0

If you've been using an app for speed, how far off is the speedo? % not mph, if you're consistently off x mph, thats a speedo issue, not related to gears/tires/improper calibration.

If you're off by 10% speed, just add 10% to your calculated mpg, thats what you're really getting.

Eduskator

That's something I forgot to ask... Is OP relying on his computer's MPG estimate or is he calculating it the proper way at the gas pump? Chances are that if he's relying on the in-dash screen's consumption, he's most likely getting 8MPG instead of 10 and 10MPG instead of 12.5...

Fuelly app is really great for that. However, if his speedo is off, he'll have to do extra maths every time. lol

Adam013085

The 75 MPH on the highway isn't doing you any favors either, probably just as big of a factor if not more than the lift and tires.