RapDaddyo said:The problem with a test that is designed to reflect "real-world" surfaces is that there isn't any such thing. Road surfaces are different. Again, as Scott said, so long as the rankings don't change and the magnitude of the differences is proportional, it's not necessary to test under real-world circumstances for purposes of choosing a tire. For other purposes (e.g., predicting TT times), it would be useful to test on real-world surfaces, but which one?
for sure... what is real world?
but this doesn't address the question I'm raising... DO bumps, texture (which are really just small bumps) cracks etc. affect the relative rating of Crr of tires in a way not reflected in these test? we don't know this because we haven't seen any data that demonstrates that the ranking of tires would or would not change when tires have to go over surface textures that even approach what tires would be subjected to on the road. it's not enough (for me at least) for you to just state that it doesn't and that's the end of it... it may or it may not.. there are a lot of variables and as i said before why make all these assumptions why not just test a few surface textures with cracks, bumps etc. and see what the deal is?
and if we do know one thing for sure.. "real world" is not a perfectly flat shiny drum...
[Edit]come to think of it doesn't even using a drum change the shape of the contact patch and possibly the skew numbers as well?[Edit]