Alright to answer some questions.
Banditt: All I am saying is use of this stuff should not take place of getting tires balanced. that is why so many people have problems with equal and such.
A liquid should be used for the best damping, (I have talked about this in the past). problem is that finding a liquid with a reasonable density is hard. I know that they make some stuff for semi truck tires.
Beaker: Balnacing and damping are very different things. When a tire is balanced it is balanced as an assembly. same as externally balanceing an engine. Correct you can't balance the tire, but when I say this I mean the tire and rim together.
Tires can be problems at all speeds, and if they are out of balance are a problem that you may not notice. (not good for bearings and other drivetrain parts). when you reach certain speeds aroung the harmonic frequency of the system, then you get the problems.
the best bet is to get you tires balance and then use this stuff.