  Tidal charged spherically symmetric vacuum brane black holes are
characterized by their mass m and tidal charge q, an imprint of the
5-dimensional Weyl curvature. For q>0 they are formally identical to the
Reissner-Nordstr\"om black hole of general relativity. We study the
thermodynamics and thermodynamic geometries of tidal charged black holes and
discuss similarities and differences as compared to the Reissner-Nordstr\"om
black hole. As a similarity, we show that (for q>0) the heat capacity of the
tidal charged black hole diverges on a set of measure zero of the parameter
space, nevertheless both the regularity of the Ruppeiner metric and a
Poincar\'e stability analysis shows no phase transition at those points. The
thermodynamic state spaces being different indicates that the underlying
statistical models could be different. We find that the q<0 parameter range,
which enhances the localization of gravity on the brane, is thermodynamically
preferred. Finally we constrain for the first time the possible range of the
tidal charge from the thermodynamic limit on gravitational radiation efficiency
at black hole mergers.
