Replace ladder treads by unbolting the used piece, removing it and then bolting a new tread in its place. More commonly referred to as ladder shoes, a single bolt typically retains each ladder tread; a wrench or socket set is typically necessary to loosen and tighten the bolt.
Ladder shoes are articulated metal pieces bolted to the bottom of upright ladders. They are typically padded with rubber grips to prevent slippage on a variety of surfaces. When damaged, shoes are less effective at keeping a ladder in place, increasing the danger of climbing on the ladder.
An extension ladder, which braces against an object and has an adjustable height, uses two ladder shoes. As the main force of the ladder pushes against the shoes to prevent slippage, it is important to ensure their good working order prior to use. A fixed ladder, which is free-standing and may or may not have an adjustable height component, uses four ladder shoes to keep the unit level and stable. It is important to inspect the shoes, as well as the rest of the ladder, for good working order prior to use.
The U.S. Occupational Safety and Health Administration outlines safe use of ladders in publication 3124-12R 2003. According to code, defective ladders must be tagged as such and taken out of service until the defect is repaired to original specifications.