Pick out planks of wood that are made from hardwoods such as oak, yellow pine or whatever the other floors in your home are made from. Cut them roughly to the dimensions of your existing treads or to the standard 10 inches deep by 3 1/2 feet wide using a fine-toothed wood saw. Sand the nose of the tread to smooth out the edge and front corners with 120-grit sandpaper.
Place the planks on a solid surface, and sprinkle some gravel over the top of them. Step on the gravel with a pair of boots to create dents in the wood. Hit the planks with an awl to make poke marks. Hammer over the surface to create larger indents with a hammer. Scrub a few areas with a wire brush. Poke small nails in random patterns to make fake worm holes.
Stain the planks with a dark stain like walnut using a paintbrush. Work over a tarp, and wear gloves when working with stain. Wipe off the excess stain with a clean rag. Dry the stain according to the manufacturer’s directions.
Sand a few areas on the planks along the edges to show wear through the original finish. Use a wood file or an electric sander, and feather the edges to make the effect look real.
Stain the planks again, but this time, use a lighter stain. Repeat the procedure of covering the wood, wiping off the excess and then drying the stain.
Sand along the nose of the tread in one or two areas. Go below the stain to the raw color of the wood underneath.
Cover the distressed treads with two or three coats of polyurethane varnish using a fine brush. Sand lightly between the coats with 0000-grade steel wool to help the layers bond well.