If you've ever had the misfortune of stepping on freshly paved asphalt and sinking into the ground a little, you'll know the tar in asphalt is difficult to remove from shoes and other bits of clothing. DIY blog Tip Nut has a few tricks to getting it off, including using olive oil as a softener.
To start, cover the stain in olive oil, then let it work into the material to soften the tar for about an hour. If the tar is gone, you're done and you should wash it up with soap and water. If it's not or a stain still remains, you need to use a solvent, like petrol. Soak a corner of a rag in petrol, then apply it to the stain in a dabbing motion. It should come right up now, and again, remember to clean it with soap and water. Olive oil and gasoline aren't the only common household items you can use, check out the Tip Nut post below for a full list.