  Doncheski and Hewett have recently shown that the ratio of neutral current to
charged current cross sections, $R={\sigma_{NC}}/{\sigma_{CC}}$, can provide a
more sensitive probe for the existence of heavy leptoquarks at HERA than the
usual proceedure which makes use of neutral current asymmetries. The apparent
reason for this is that the Standard Model expectations for {\it both} of these
cross sections are modified by the existence of such particles in a
semi-coherent manner. In this paper we apply this technique to extended
electroweak models whose spectrum contains both a $W'$ and a $Z'$. We find that
measurements of $R$ can, for some models, substantially increase the HERA
search range for new gauge bosons beyond that which can be probed using the
more conventional asymmetries.
