They are almost impossible to break, almost. I have broken two of them and both times i broke them i hit something so hard they had to break. cool thing is that you can send them into RPM if you do break one and they send you back a replacement part at no cost. I usually bought a whole other pack of them and then sent the broken one in just so i would have a stockpile of spares. Plus with them being such soft plastic, they will start sagging over time if you let the truck set on the tires for long periods of time.