Would the following procedure work for quickly finding heavy/light spots on an unmarked tire?
Using the Parnes, etc. balance the bare wheel with temporarily attached weights. Install one bead of the new tire onto the wheel with the other bead suspended off the rim in the air. Push the installed bead all the way to the rim on the opposite side of the wheel. This should center the tire about the axle, same as when it's properly installed. Should be pretty easy to push the bead over tight against the rim. Now, find the heavy/light spot of the tire with the Parnes. Since the bare wheel is temporarily balanced you've identified the tire's heavy/light spot.
Would the following procedure work for quickly finding heavy/light spots on an unmarked tire?
This should work fine since we're just doing a static balance. All you need is the tire centered about the axle. Installing one bead should accomplish that. Doesn't make any difference where the tire's located left-to-right on the axle as long as it doesn't affect the friction of the Parnes bearings.
My experience is that you cannot find the light spot on the tire unless you balance the rim, install both beads, and also fully inflate the tire.
Only issue I see with this procedure is the length of the Parnes axle. It may not be long enough since most of the tire's width will be located outside the wheel, increasing the overall width. But one could just extend out a support for the Parnes on one side which would pass through the tire effectively lengthening the Parnes axle.
This should work fine since we're just doing a static balance. All you need is the tire centered about the axle. Installing one bead should accomplish that. Doesn't make any difference where the tire's located left-to-right on the axle as long as it doesn't affect the friction of the Parnes bearings.