You have to remember when figuring out mpgeez that you are actually traveling 11.4 % more miles than the odometer says.
I tried some 185/70-14s (from my del sol) but they bumped something in the rear when going up a drive lip. Based on that experiement, I bought some 175/70-14's, hoping for some increased road stability. About 5.4% larger, but the low end torque was pretty bad and the mpgeez went down despite the size increase. So I am phasing those out and have decided to shift to 13 in wheels and 155/80's. That has improved mpgeez signficantly (up around 50 now) and low end torque is up to the baseline. Handling is actually nicer, aided by my diy upper rear sway bar.
The message is that bigger tires for me didn't improve handling. They did lower rpms/mile, but also mpgeez to the mid 40's or lower.