Yep, Because of the bulk of the tires, as well as materials some rims are made of, it's getting to be quite common for tire mounting shops to put the balancing material in side the tire. I.e. plastic beads, sand like material in a thin plastic baggie. theory being as the wheel turns faster the material is slung to the spot its needed to balance the tire.
Proud to have served with and supported the Units I was in: 1st IDF, 9th INF, 558th USAAG (Greece), 7th Transportation Brigade, 6th MEDSOM (Korea), III Corp, 8th IDF, 3rd Armor Div.
1980 Ebbtide Dyna-Trak 160 Evinrude 65 Triumph