Because of this post, and this post alone, I am currently sinking all my spare change into a set of 8 Kelly Armorsteel KDA drives. Wanted to go for traction over rolling resistance. If they fail me, plan on sleeping with one eye open
I have balancers on all axles, putting in counteract in the new drive as well.
My plan is to shorten up my operating radius, which means lots of hills, lots of unstable two lanes, more bad weather, and when I do run long, it will typically be out west.
Time will tell how important rolling resistance numbers are I guess, because I have thrown all that out the window with this purchase.
I've already determined that side skirts were worthless. If anything, I'm doing better with my new trailer without them, especially in strong crosswinds.
I've tried lots of things for fuel economy in recent years. Best things go back to driving style, tire pressure, speed, and lots of horsepower.