The reason for the B rating has to do with test methodology. The wet traction rating is conducted with a tire locked (not rotating) and it favors tire designs that have longitudinal grooves, which the CC does not have. Instead, all modern cars have ABS and the tires will continue to rotate, which allows the lateral V shaped grooves of the CC to function. So the B rating is an artifact of test methodology, not reflective of real world wet traction.
I’m not claiming that the CC is the wet traction champion, but it’s a top performer, better than some tires that may have an A wet traction rating.
Here’s a test of the CC2 vs Michelin’s MXM4, which is AA rated:
