My rear Rim has a slight crack which cause me to have a slow leek in my tire which is a run flat tire. I want to replace it with a new rim but after I take the lug nuts off the rim is still held tight I'm sorry to sound foolish but what else is it that is holding the rim in place? I had flats in the front tires before and the rime comes off after taking of the lug nuts out is there something I'm missing to do? I also provide a donation to the cause. I feel its an important source to have alternative information available .