I recently purchased a 2013 F150 XLT SuperCrew 3.7L. Part of the package installed was upgraded tires. The tires on the truck currently are 275/65/18. Normal tires on the truck are 255/65/17. I am seeing a problem with the fuel economy. I am unable to get above 16MPG on average. When I test drove one of the other trucks, it was around 20+ mpg.

Any thoughts on what I can do to improve fuel economy?

 

I have 4300 miles on mine, same tires and highest I got before the winter gas was 16.5. Curious where the heck you saw 20+ mpg. The computer won't read 100% accurately until you put some time behind the wheel.

 

While the 275/65x18 is an OEM stock|optional size and the wheel has close to the same diameter as the previous 255/65x17 there are the following MPG, "fuel economy" considerations ...

• PCM flash to adjust RPM (Revoutions Per Mile) for the 275/65x18 (650 - vs 694 of the 255/65x17).
  *NOTE: This will also properly adjust your transmission's shift points.
  **NOTE: The provided RPMs are FoMoCo's IDS settings.
  .
• weight of rims.
  *NOTE: The 18" may be (?) heavier than the 17".
  .
• weight of tires.
  *NOTE: BIG difference in P vs LT.
  .
• tread width.
  *NOTE: the 275/65x18 has a wider width (+¾").
  .
• recommended PSI of the tires. *
  NOTE: LT tires typically should be 40Lbs, while P tires are typically 35Lbs
  
  etc., etc., etc..

It ALL adds-up.
.

 

gDMJoe,

A few questions.

How do you flash the PCM? I'm assuming this would also correct the instrument panel to make the MPH, etc are more accurate?

 

Your local, friendly FoMoCo dealership can/could do this using their IDS (Integrated Dianostic System) tool for a small fee, though they may (?) do it for free depending upon your relationship. *RECOMMEND*

-OR-

You could purchase a hand-held tuner (e.g. SCT) and perform the change yourself though you're talking $$$$$.

BINGO!
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