What I've found is the smaller the beads, the LESS movement around the tire. After feeling a front tire vibration I'll get them to move by running over those road rumble strips between 40 & 60 mph.. Any faster I noticed they didn't move much & had to do it again.
The reasons for said beads not moving?
1.) The small glass beads have more edges touching (friction) thus holding onto each other. When they get a rubber coating, the friction grows.
2.) The larger diameter ceramic beads are heavier & over come that friction thus move around the tire. One tire I removed all the beads were coated with tire rubber but I never had to run over any rumble strips.
Some tires will have internal cooling ribs & the small beads get trapped between a few ribs and just don't move. I then add an extra ounce or so, but that doesn't take care of the issue totally. Besides, it's more un-sprung weight.
The ceramics being larger fills the ribs quicker & the rest can flow over. BTW: I never had to use those rumble strips with larger beads.
I've also read some have toss in 1/4" ball bearings but I know from 'shot peening' the rim takes a beating. NOT interested in that & it's noise.
I'm also not sure if glass marbles is good either. I remembering them cracking in half back in grade school.
So now now I'm wondering if even larger ceramic beads will work better?
As for all my future tires that have internal ribs, I'll be grinding away the ribs along the center line for the beads to flow around smoothly.
SO, hope this helps those who have vibration issues. _fm
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