  The emission line spectra of WR stars are often formed completely in the
optically thick stellar wind. Hence, any assumption on the wind velocity law in
a spectral analysis has a profound impact on the determination of the stellar
parameters. By comparing Potsdam Wolf-Rayet (PoWR) model spectra calculated
with different $\beta$ laws, we show that the velocity field heavily influences
the spectra: by using the appropriate $\beta$ laws, the entire range of late
and early types can be covered with the same stellar model.
