  We show the full multiscale Persson's theory for rubber friction due to
viscoelastic losses can be approximated extremely closely to simpler models,
like that suggested by Persson in 1998 and similarly by Popov in his 2010 book
(but we don't make any use of the so-called "Method of Dimensionality
Reduction"), so it is essentially a single scale model at the so called large
wavevector cutoff. The dependence on the entire spectrum of roughness is
therefore only confusing, and we confirm this with actual exact calculations
and reference to recent Lorenz et al (2015) data. The multiscale aspect is
irrelevant with respect to the real critical issue: the choice of the "free
parameter" best fit truncation cutoff, which shows the models are mainly
fitting equations. In this sense, we provide at least a very simple one.
