Carpet tiles are ideal for stairs and more straightforward to fit than other floor coverings, but stair nosings must be used. These hold the upright tiles on the stair risers in position so they cannot fall forward and cause you to trip, and the nosings cloak the raw tile edges.
For domestic users who do not want to use nosings, you could install a tile on the tread only, with a UPVC ramped trim to hide the edge of the tile. The risers can be painted, providing the comfort of tiles on the treads without needing nosings.