I just had my P-zero's mounted on the 3 piece rims. My friend, a Ford dealer, has a Hunter "Roadforce" balancer. This thing is absolutely the trickest piece of automotive machinery I've seen. It calulates the width, diameter and backspace, and checks for runout, roundness and imbalance. It then tells you how much weight to add, but actually locates the weights so they are BEHIND the spokes...so totally invisible from the outside. It also does a weighted run-in to make sure the beads are seated. One last thing it does is check for flat spots and hard spots on the tire. I'm impressed...