I have a pair of Schwalbe Little Big Bens that have the same type of "whirr" on smooth pavement (40mm nominal...38mm actual). The center tread pattern is broken enough that it creates that sound. And I'll admit that it's an annoying noise, and the Schwalbes are hanging up on a hook in my shop right now because of it. I have smooth tread Kenda Kwick Tendril tires on that bike and they are whisper silent (but smaller...37mm nominal...33mm actual).