Back in the 70s, the original 201 Standard Libelles didn't have the little plastic half-embedded wingtip wheels you see on most of them. Woody Woodward (W1 for those with good memories) got the kit from Glasflugel to install them on his glider. Concerned about drag, lazy, or maybe just with an inquisitive mind, he installed a wheel on one wing only and flew around with it for a year. Unable to tell any difference, he stopped worrying about it and installed the second one.
Three years ago when we were refinishing my ASW 24 wings, UH built the molds and installed a similar set of wingtip wheels in my glider. I love them! Now I can move the glider around by myself on the ground, even (especially) on pavement. They're half embedded in the wingtips so the profile is actually slightly less than that of the factory's rubber wingtip skids.
Chip Bearden
JB