I've had mine (see signature) since 05/01, presently only 260k on it. I've run 305/70/16s except for the 265s that were on it when I got it and 1 time when I ran another set of 265 Michelins (total garbage, dry rotted in under 30k) anyhow, I'm running 1900 rpms GPS indicates 73mph. Not trying to correct for 5mph slower on the speedo than actual, GPS, I'm getting consistent 15.8mpg, keep in mind mine is 4wd so there's extra weight and a bit of drag even in 2wd, I rarely tow BTW. That said, I think if you were to go with larger tires, I know guys running 315s (4wd rubs the front control arms when turning lock to lock) that have no issues in the rear, you'd be able to lower highway rpms. I've found, at least on my setup, the sweet spot, rpm wise is 1900 (73mph) to 2100 (about 79-81mph). I'd get 2 good wheels (salvage yard) and try the 315s, keep the smaller tires for hauling and see how that works for you. Would be interesting to see difference, rpm wise, with 4:11s and 315 tires. Probably some calculator online that might help figure benefit before spending and $.