Tires which are thought to be at-risk of spinning on the rim - usually dirtbike tires run at low pressure, though some '70's streetbikes were fitted with them as well - are fitted with clamps that are tightened with bolts extending through the center of the rim, looking somewhat like multiple valve stems. They mechanically clamp the tire beads to the rim, preventing the rim from turning independantly. These complicate matters for changing (and balancing if there is only one) tires and tubes...