Ecoboost Mileage difference with larger tires
 

There are hundreds of threads on this subject but I am looking for Ecoboost owners that have increased tire size.

I am thinking of going from 275/55/20 to a 275/65/20. It adds about 3" to the diameter. I am also adding a 2" Autospring leveling kit.

Also Eco-boost performance differences when pulling trailers or in general. I pull a tractor from time to time that is about 7K pound with trailer. It pulls great now.

Any thoughts would be appreciated.

Did you read any of the "hundreds of threads"?

They all mention decreased mileage with larger tires.

i would expect atleast a 1-3mpg loss depending on driving habits, axle ratio, and current tuning (if any) on your truck.

Is that REAL mpg loss, or just a loss because the odometer/speedometer are not re-calibrated. That is, changing tires would account for a 5-6% increase in speed (over a non-calibrated speedometer).

The odometer would also understate your mileage by the same amount. So, if your odometer reads 100,000, you have really traveled 105,000 miles.

This would also understate your mpg.

No offense OP but there are tons of thread regarding this... If you want MPG don't increase tire size, difference is brutal sometime, especially if you go wider, heavier and more aggressive.

It your case going to 275/65R20 will increase by 2in (not 3 like you stated) and with a 2in lift you can expect a good real 2-3 MPG drop after speedometer correction.

The heavier the tire or more drag that it produces from the aggressive tread or extra width the more you are in boost and mpg will go down. That is why ford put Goodyear SR-A's on them from the factory as these tires are one of the lower rolling resistance tires available. with those tires and a 3.31 rear end they were able to achieve their good epa figures

really?
of course its a real mpg drop. Taller/Heavier/Agressive tire will increase drag, in turn increasing fuel consumption rendering lower mpg.

If I had a dollar for every time I saw one of these threads... Do you honestly think putting a level and 2" larger tires won't make a big difference? If you're that concerned with your MPG then keep it stock..

I leveled mine, kept stock size but put Duratracs on, have lost every bit of 2 mpg's. Had a TSB reflash done at the dealer, and that cost me another mpg.

I have BFG ATs in 275/70R18s(33.2") and the 1.5" AS Leveling kit on my Ecoboost.

I still get good mileage IMO. I've been getting 17-18 MPG @ 70 MPH with 2 dirt bikes in the back. Pretty consistent with that.

I had a slow two lane drive (more like 60-65 MPH) with 2 dirt bikes in the back and managed to squeak out 20 MPG.

I don't do a ton of empty highway driving but saw around 19 MPG @ 70 MPH on my last trip.

I'm at a little over 9000 miles on my truck.

If you want to maximize mileage, pick a smaller, lighter and less aggressive tread.