  We consider the physical properties of four dimensional black hole solutions
to the effective action describing the low energy dynamics of the gravitational
sector of heterotic superstring theory. We compare the properties of the
external field strengths in the perturbative solution to the full $O(\alpha')$
string effective action equations, to those of exact solutions in a truncated
action for charged black holes, and to the Kerr-Newman family of solutions of
Einstein-Maxwell theory. We contrast the numerical results obtained in these
approaches, and discuss limitations of the analyses. Finally we discuss how the
new features of classical string gravity affect the standard tests of general
relativity.
