There is no better way to keep the carpet on your stairs clean and looking good than installing a length of clear vinyl stair runner over them. Vinyl is very durable and will not have to be replaced for a long time after installation. And because it is clear, you will be able to see the color of the carpet through the vinyl. That means that there is no need to find a colored vinyl runner that will go well with your decor.
Estimate the length of plastic stair runner that you will need for each continuous length of stairs that needs to be covered. Measure the rise and run of one stair. Add these numbers together. Then multiply this number by the number of stairs that need to be covered for each continuous length of stairs you will be covering. For example, if the stair rise is six inches and the stair run is nine inches, you will need 225 inches 18.75 feet of vinyl.
Add an extra two feet to the estimated length needed for each continuous length of stairs. You can trim the excess plastic when all of the stairs are installed and covered. This is the amount of plastic stair runner to purchase for that particular set of stairs. Repeat this process for every set of stairs you wish to cover with plastic stair runner.
Drill three holes into the two-inch by 36-inch finished piece of wood--one hole two inches from each end, and a third hole in the center. Each hole should be drilled in the center of the piece of wood width-wise. These holes should be large enough to accommodate a screw without catching the screw's threading.
Roll the plastic stair runner out so it sits on the edges of each stair. Center the plastic over the stairs. Screw the top end of the runner either into the rise of the last stair or into the floor above the last stair six inches from the edge of the first rise. This will become the main anchor point for the plastic stair runner.
Install a stair rod at each point that a stair run meets a stair rise. The number of stair rods you will need is determined by the number of stairs you will be covering with runner. Styles and colors will vary, and are available over the internet as well as in hardware stores. Screw the end of each stair rod into the corner of each stair with matching screws.
At the bottom of the last stair, screw or staple the runner to the face of the stair rise and trim the excess runner with a utility knife.