[Kut_Throat]

I have a 2004 6.0 CCSB with a 4” lift on 315/75r16s and hand calculated I am looking at 13-13.5 all year long. No matter if it’s highway or city, summer or winter fuel. The truck is bulletproofed and has just about every popular 6.0 mod. Straight pipe exhaust and all that. Is this what everyone else is seeing or should I start looking for a problem?

 

[Weatherlite]

With tires like that a a lift, you're probably in the right ballpark. Sadly, you're getting better mileage than I am currently. Not sure what it is, but my rig HATES winter fuel. I'm lucky if I get 13 in the winter. lol However, I WAS getting 16 in the summer as an average. Then, I installed a PHP FICM tune and mileage bumped by about 2 MPG...3 in some cases. So, that may be route you'll want to look into. I would also make sure you've got decent fuel pressure. From what I understand, lower pressures create larger droplets which don't burn as easily. Probably miniscule, but something to consider. Other than that, I've found my biggest improvement came from my right foot, the FICM tune, and making sure everything was running smoothly.

 

[bluedorito60]

Amen to what Weatherlite said. I’m running 320/20s with a 3” leveling kit on my 07 king ranch.

Ficm with Atlas40 gets me high 13s around town and 18+ highway babying it (75 mph max)

 

[Dave Whitmer]

You are getting what your rig should expect.

 

[Dave Whitmer]

The 315s are killing you.