Going to try swapping back to stock wheels.

If you tot up all the 12V currents that all those accessories are
drawing, you can figure out the extra watts of drain and then for
how long, i.e. watt-hours. You get maybe 10 KWh of actual propulsive
or electricity-generating energy out of a gallon of gas, figure the
proportion of the 12V accessories [noting that the DC/DC converter
that feeds them is ~ 90% efficient] and see if it would explain the
ding in what you think your MPG *should* be.
.
Then, to prove the theory, take some long runs without any of the
12V accessories and the car's electronics at the minimum baseline
needed to make it go, which is ~ 300W, and see if you get a
significant improvement.
.
I don't think you'll find much difference. There's a great mis-
perception that 12V stuff and lights and whatever are a significant
drain on a traction battery. They aren't. It takes *way* more
power to push the car than thump the subwoofer.
.
_H*