The last time I did qualitative traction testing was in 2009. See this
post.
Since then I have not needed to build a traction limited drivetrain, so the actual number was not essential. We did some qualitative testing for the polycarbonate on the bridge this year. We were looking for the best material that we had access to, so A>B testing was adquate.
Admittidly, I would like to have a library of exactly the information the OP is asking about, but it is less important than foundation work that needs to be done with/for the team.