Changing a tire with a foam insert instead of a tube can be very tough on the finish of your bike's rims. The common practice is to fasten multiple locking pliers to the rim edge to hold the bead of the tire down. Many modern bikes have colored rims with an easily damageable finish. I wrap the jaws in duct tape to protect the rim finish. You will be able to see when the teeth of the jaws start to come through the tape. That means it's time to replace the tape.