Get a home dry cleaning kit. These kits are available at grocery stores or discount chains. Make sure to buy the non-flammable dry cleaning fluid. Pour the fluid on a cotton ball or white cloth and press down on the tar stain. Keep patting and pressing until the tar is gone.
Try a solvent-based cleaner such as Goof-Off or Goo Gone. Gently pat the stain and press it with strong, firm pressure until the tar lifts.
Purchase a heavy-duty liquid disinfectant such as Lestoil. This type of cleaner breaks up grease and stains.
Head to the automotive aisle and buy a tar and bug remover intended for cars. Follow the directions for tar removal. You may want to test the tar remover on a hidden patch of carpet before using it on your tar stain, since these types of cleaners are made for use on automobiles, not carpet.
Buy a carpet spot removal kit. Found at home improvement stores, vacuum cleaner stores or on the Internet, these kits contain professional spot remover materials.
Contact a carpet-cleaning professional. If the tar is clinging on for dear life, trust the experts. After all, it is much cheaper to pay to have your carpet professionally cleaned than to buy new carpet. An added bonus is that you clean all your carpet, not just the spot with the tar.