Circumferential tire grooves form pipes in the contact patch and generate the nuisance noise, for which the fundamental natural frequency is approximately 1000 Hz for passenger car tires. The frequency coincides with the peak of pass-by noise spectrum. Therefore, controlling the groove resonance is of a main motivation of this paper to reduce environmental noise. If one lateral slot end is terminated in tread rib and if the other end merges to a circumferential groove, it is found that the slot performs as a side-branch or a Helmholtz subresonator to counteract to the pipe resonance. The slot parameters, such as cavity volume and the change in section area, determine the resonant frequency and effectively influence on the acoustic characteristics of whole groove space. Optimal slot geometry is widely investigated by using numerical analysis and validated by experiments. It is shown that the proposed tread design can significantly reduce groove noise without sacrificing other performances.