Other issues that decrease mileage

[audiocontr]

I'm trying to determine if my new tires could really effect mileage as much as they seem to. A reduction of 3-5 MPG! I'd like to eliminate other possibilities first.

I have an AE and everything specs out perfect on the numbers. Cyl 8 does show up at 5% decrease in inertia, but this appears pretty common with the CPS. Speed is calibrated to tire size (33")

All couplers are clean, no boost leaks, brand new up pipes, Superchips 1705 set at hi-perf, driven easily. My route was 50/50 highway and city and i wound up at 13mpgs. No noticeable loss of oil, fuel filter does not appear dark with oil. Truck has plenty of power.

Any recommendations?

[revolvingsteel]

You probably know this already, but just in case you could try this.
Welcome to guzzle's Exhaust Backpressure Sensor Cleaning Maintenance Web Page

[audiocontr]

I appreciate the suggestion, but the AE shows normal response from the sensor.