Scalloped – Cupping Damage:
Primary type wear experienced with worn shocks. Loss of shock dampening allows for greater tire load variance and allows build up of resonance with the rhythm of a road quickly resulting in cupping wear. Tire companies can measure early scalloped cupping in new truck tires on older shocks within a few hundred miles on a rough road; however, the same test conducted with new tires and new shocks does not experience similar damage for tens of thousands of miles. This can impact the life of the tire as much as 50%. For this reason, it has been found cost effective to change shocks when replacing tires on modern Heavy Truck suspensions.