In my other RV
(38' diesel), they put balancing sand in the tires at the last tire change. I would NOT recommend it or similar products for our flying RVs.
Two issues - first, the sand all ends up at the bottom of the tire while the vehicle sits (or probably when flying). Typically, I feel more vibration than without the sand for the first few miles. Later it gets better, but not sure it's really helping. Our flying RVs would likely see this initial imbalance on landing, arguably the worst time to be out of balance.
Second - the sand gets in your tire gauge and screws up the back flow valve (and maybe the tire stem valve too). They are supposed to install a sintered metal filter below the tire valve, but I'm not sure whether my installer left them out, or whether they are just ineffective...