I searched through several pages of Google results, I can find only anecdotal evidence of effectiveness. No tire or vehicle manufactures have posted test results that I could find.
My engineering nature tells me to be skeptical without test result from qualified laboratories or tire manufactures. I would not use them, I prefer to do things I "know" work, as opposed to things I "think" work. a fine philosophical line I know, but I drew it and I ain't crossing it. 
Beyond my engineers opinion, it is your time, money, and safety do what you want, let us know your result.
It works just like your washing machine does - the beads are like the water, for instance, in the tub, you spin it, and it flings to the outer sides and the rotation and intertia distributes it evenly.
Like stirring a 2 quart juice container of koolaid.
Your washing machine can be off balance with one or two large heavy items inside ( don't try this with 1 inch diameter ball bearings inside your tires..), but small rolling moveable balls will even out, just like anything added to a liquid and spun.
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We don't need engineers when drinking the koolaid tells us all we need to know. 
No, no, no.
This has been gone over before. This is not correct.
Well, yes it is correct. Let's take a heavy wet towel and put in our washing machine on one side clumped up (that represents the chunk of tire and rim that is too heavy on one side/area). Our inner washing machine tub is the inside of the tire. We spin it around and it wobbles like heck.
We open the tp of the washing machine and pour in a thousand small ball bearings, they fall on the wet towel and around it to the tubs bottom ( the inner wall of the tire). Spin it up, and wala, the ball bearings, since they roll around and move, balance the washer.
Now, it is slightly different inside a tire on a bike, because you have GRAVITY to deal with, and the tire is spinning while in a vertical orientation, it's axis perpendicular to gravitational pull instead of aligned with it in the case of the washing machine. However, a side loader washing machine will do the same thing (take out the 3 restrictive bumps that help sling the clothes ) and you'll achieve balance, even with the mass moving toward and away from gravitational pull vector every revolution, like a bike tire.
So sorry, it is THE SAME THING. (except again, for adding the other factor on spin up- movement of the entire mass perpendicular to gravity in the case of the bike- affecting the load of ball bearings or the beads in the spin up)
Then add the road, hills and valleys, bumps, turning and tipping the bike, the flattened tire at the pavement contact point...
