Fuel mileage mods and alternative fuels

With my DD I am contemplating going to pure synthetics for the drivetrain, and most importantly going to smaller tires for the non-winter months.

I know that when I went from 225/75/15's to 30x9.50x15 mud tires power dropped some of course as did mileage.

I now have other rigs to drive in the winter, so I will drive the other less efficient rigs when needed.

I am hoping that smaller street tires, mixed with slowing down and thinner lubes will get me into the mid to upper 20's which I did see in the past.

Truck is a 98 Tacoma 4-cylinder 4wd. Dead stock with 93K on it.

ROB