This is how a Jawa can be easily amused...
Klunkers are typically old cruiser frames with knobby tires and other MTB adaptations, right? Well, in trying for a lower-rolling resistance tire on my mountain bike for when I ride it on local stone dust paths, I've done the inverse.
I used a set of Schwinn Typhoon cord repops I had. The smooth tread definately rolls easier, and the rounder tread cross section makes for a narrower contact too. Plus, the white walls actually look pretty cool on the white rims against the olive paint.