Overdrive or don't worry about it? !

3.23 @ 70 mph with 26" tire = 2950 RPM

3.23 @ 70 mph with 28" tire = 2750 RPM

so at the cost of an extra set of rims and tires along with the time and pain in the *** to change tires just for a trip you are only saving 200 RPM.
.


But compared to swapping a chunk?

...just for a 200 mile highway drive.