More likely it's tire cupping. Check your tire visually,

来源: 于 2012-01-14 23:29:38 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

see if it looks like a gear? You can try wheel alignment to avoid getting worse, or change the tires if the vibration bothers you.

Does anyone know if tire cupping has safety issue?