  In this paper we investigate the statistical properties of the Tully-Fisher
relation for a sample of 32 galaxies with measured distances from the Cepheid
period-luminosity relation and/or TRGB stars.
  We take advantage of panchromatic photometry in 12 bands (from FUV to 4.5
$\mu$m) and of spatially resolved HI kinematics. We use these data together
with three kinematic measures ($W^{i}_{50}$, $V_{max}$ and $V_{flat}$)
extracted from the global HI profiles or HI rotation curves, so as to construct
36 correlations allowing us to select the one with the least scatter. We
introduce a tightness parameter $\sigma_{\perp}$ of the TFr, in order to obtain
a slope-independent measure of the goodness of fit. We find that the tightest
correlation occurs when we select the 3.6 $\mu$m photometric band together with
the $V_{flat}$ parameter extracted from the HI rotation curve.
