  The determination of the LSR is still a matter of debate. The classical value
of the tangential peculiar motion of the Sun with respect to the LSR was
challenged in recent years, claiming a significantly larger value. We show that
the RAdial Velocity Experiment (RAVE) sample of dwarf stars is an excellent
data set to derive tighter boundary conditions to chemodynamical evolution
models of the extended solar neighbourhood. We present an improved Jeans
analysis, which allows a better interpretation of the measured kinematics of
stellar populations in the Milky Way disc. We propose an improved version of
the Str\"omberg relation with the radial scalelengths as the only unknown.
Binning RAVE stars in metallicity reveals a bigger asymmetric drift
(corresponding to a smaller radial scalelength) for more metal-rich
populations. With the standard assumption of velocity-dispersion independent
radial scalelengths in each metallicity bin, we redetermine the LSR. The new
Str\"omberg equation yields a joint LSR value of V_\sun=3.06 \pm 0.68 km/s,
which is even smaller than the classical value based on Hipparcos data. The
corresponding radial scalelength increases from 1.6 kpc for the metal-rich bin
to 2.9 kpc for the metal-poor bin, with a trend of an even larger scalelength
for young metal-poor stars. When adopting the recent Sch\"onrich value of
V_\sun=12.24 km/s for the LSR, the new Str\"omberg equation yields much larger
individual radial scalelengths of the RAVE subpopulations, which seem
unphysical in part. The new Str\"omberg equation allows a cleaner
interpretation of the kinematic data of disc stars in terms of radial
scalelengths. Lifting the LSR value by a few km/s compared to the classical
value results in strongly increased radial scalelengths with a trend of smaller
values for larger velocity dispersions.
