Not surprisingly, few things get as dirty and smelling as an old pair of tennis shoes. Your feet are closed up in them for hours while you are active. There is nowhere for the moisture and odor to go. It seeps into the fabric of the shoe. To remove odor and restore a fresh scent to your tennis shoes, you will need to wash them thoroughly. A soft cloth and little detergent may revive the outside, but soiled tennis shoes require a full wash in the washing machine to revive them.
Remove any surface dirt with a stiff brush. Get into the treads to remove any trapped dirt or gravel. A soft brush will remove dried mud or dirt from the outside.
Place the shoes in a mesh laundry bag and close it securely. This will prevent the shoelaces from tangling during the wash and will keep soles from marking the inside of the washer drum.
Set to a small cycle and add ¼ to ½ cup of laundry detergent. Add laundry booster for extra cleaning power if preferred. Laundry detergent made with odor eliminating formula is the best choice, but any will do. For smelly tennis shoes, add ½ cup of baking soda to the water. This will neutralize odors.
Turn the washing machine on and allow to agitate for several minutes to dissolve and distribute the laundry detergent and baking soda. Drop the tennis shoes into the washer and allow to run through all cycles.
Remove the shoes and pat with an absorbent towel to remove excess water. Stuff the toes of the shoes with a wad of recycled newspaper and set in the sun to dry.