Although not the most effective solvent, mineral spirits will dissolve
tar,
and it is probably about the safest you could use.

If you are talking about real "tar" then mineral spirits will not do much.
For real "tar" you need Benzene. Benzene causes CANCER!

If you are talking about asphalt then mineral spirits MIGHT work. What
does work is gasoline. Gasoline is a fire hazard, of course but it
evaporates quickly and the hazard goes away.