The plasmonic properties of metallic nanodiscs and nanocones have been characterized with a view to applying them to high performance tip enhanced spectroscopic methods. The characterization used a setup based on the coupling of an achromatic inverted microscope equipped with a total internal reflection objective and an atomic force microscopy (AFM). Tunable plasmonic resonances are identified and are in excellent agreement with numerical simulations. The simulated and measured plasmonic response of the nanostructures suggest possible applications in a new generation of probes for tip-enhanced optical spectroscopy in which plasmonic nanostructures are designed at the apex of a non-metallic AFM tip. The tips enable a spectral tunability as a function of the specific material, the size, shape and topography, together with high electric field enhancement factors. The result in term of tip performances are better than those commonly used in tip-enhanced optical spectroscopy experiments such as tip-enhanced Raman spectroscopy (TERS).