Some tires can be very difficult to mount or dismount, sometimes it can be the fault of the installer, but sometimes the combination of the tire and the wheel can make installation and removable a bear. Example: I have a haulmark cargo trailer at work. The 14 ply tires that we installed on it are extremely hard to install and or remove. It is not due to the stiffness of the beads, it is due to the thickness of the beads. The beads are too wide to fit into the recess of the wheels that allow the tires to be easily installed or removed. A narrower bead tire presents no issues. Another example is on my personal pickup truck. I have a set of 18x9 vision wheels, they look very cool and they are extremely hard to mount or dismount tires on due to the design of the wheel. The recessed portion of the wheel is simply to far away from the outside of the wheel to allow for easy installation or removal. These are MY wheels that I picked out and I HATE them when it comes time to change tires. I have been selling and installing tires for over 30 years and I know what I am doing. I can't remove tires from these wheels without damaging the wheels (scratches). If you measure the width of the beads of different brands of tires, they are all different. The thinner the bead, the easier it is to mount the tires. A very narrow recess in the center of the wheel makes mounting harder.