Really does make a huge difference having a good clean, scrubbed rim to get any dirt, tar if applied in the past etc off. Fresh grind on the rim and these pads really do come alive, I have used these on about 4 different rims smooth and grinded. They will work nicely on a smooth rim and they will work amazing on a good grind and be extremely loud too. The new vee backings and running Phat Pad material looks very promising from what I have seen of the set given to Matt, look forward to getting myself a set to see how they hold up.