Have only used once, but mixed about their use. On the one time utilized, it was on a gravel pad, placed down the rubber strip, backed up and all was good. Not completely. When both of the leveling pieces tipped back to level the trailer, they both were cut in half by the wedge. Don't know if this would happen on pavement, but certainly seems to be the case on a gravel surface. In addition, multiple holes in the pieces of rubber after this first use. Don't use the rubber strip unless needed. Try without first.