Quick Question
I always lay my wheels face down on a towel (to catch the center cap and not damage it). Then I use a large piece of dowel rod that I place inside the center cap. This applys even pressure to the little clips on the center cap. I learned that if you don't apply even pressure, you'll break off a clip or two every now and then. Then I just gently tap the dowel rod with a hammer to remove the center cap.
If you don't have a piece of dowel rod, anything similar that you could hammer on will work.





