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A lot depends on the type of driving you do. Mileage seems to suffer at speeds of 65 MPH and above. I only drive on the interstate once or twice a year so I deal mostly with 55 MPH and some in town driving. My tires are only 34.5" Trail Grapplers (77lbs. each).I corrected my speedometer with my SCT X4 and run an MPT 91 tune. This is my lifetime avg. minus 4.7 miles. Some yahoo at the dealership reset it.
I have 35's on my ecoboost (35x12.5R17) that are true 35s and measure about 12 inches wide. I have 3:55 gears and I get 13.5 average (mostly highway driving with lots of lights). I may have averaged 15.5 stock. The 2 mpg sacrifice is very much worth it to me. Chump change.
What kind of tail light guards do you have? Do you have any more pictures of them?
I'm definitely not trying to save the planet, just trying to make sure I don't get myself into a worse situation than I had with the Jeep.
Beautiful truck, love that color! I'm finally gonna get a chance to drive a good distance since I put the performance upgrades on, so we'll see how that affects the gas mileage. I got 25 bringing it home on the freeway completely stock. I'd like to see 15-16 with the 35's. Have you done anything to your truck by ways of intake or programmer?
I had a JK before and loved it. I had 37s on it and got maybe 11mpg in that thing. The amount of room I have in my Supercrew is amazing compared to any other vehicle I've owned. Definitely won't go to anything other than an F150 from here on out
It's funny you asked about a programmer. I just order the new Diablosport i2 last night and it gets delivered today. It comes with 6 tunes. I'm going to give the 87 tune a try and see how my gas mileage improves.
I had my 11 for 45k miles. first a 2" level with 285/60/20 duratracs, then a 4" rancho and 285/65/20 BFGs. I also had an SCT X3 in it. I usually got 14-15 all the time.
my new 14 only has 2200 miles, 2" level and 305/55/20 Mastercraft MXts and its averaging 13.9. It should get a little better with some miles, and maybe a tune, but don't expect much more.
I'm actually on my 4th set of tires on the 14. had stock Pirellis for 600 miles, put 35/12.50/20 MXTs on it for about 300 miles, then 275/65/20 Mastercraft AXTs for about 500 miles, now the 305/55/20 MXTs. The muds and wider tires hurt mileage considerably
If you pay close attention, you can see when I replaced tires with heavier Goodyear Wrangler Adventures.
Were the original tires really worn? Did you replace with same size?
Also I wonder about the true distance reading since a worn tire has more revolutions per mile than a new one and that effect can show a sudden drop in MPG reading, even though you might be going the same distance per gallon as before.
I installed 285/65R20 BFGs (as tall as some 35s but narrower/lighter) on my 14 at like 1000 miles, averaged 13.8 lifetime MPG for 17,000 miles, went to 285/70R17s and in 3,000 miles the lifetime is already up past 16 and I break 18 pretty easily on highway trips, even at high altitude and with tons of camping gear and a bike rack hanging off the back.
I appreciate all the info guys, please keep it coming!
I just put about 100 miles of pure freeway driving (including stop and go LA traffic) and got about 21.5 mpg. If I can keep that about 17-18 with the 35's, I'd be ecstatic. I'm running the 87 octane tune on my Superchips, so we'll have to see if the Mileage XSaver is any better.
11-02-2015, 04:11 PM
