Low speed wobbles are usually a sign of a bad tire, or something bent. If you can, jack up one wheel at a time and give it a spin. If you're unsure, get something to use as a reference like a 2x4. Place it close to the section of tire you're inspecting and watch the distance from the rubber to the edge of the 2x4. Obviously, the distance should be constant. Even a few mm could cause a problem. Look for bumps on one spot of the tire. Feathering or cupping - many times around the tire - are other problems, but won't cause this low speed wobbling.
If you do find something, this can cause high speed vibration too.