When you say wobble, do you mean from side to side, or is it more of a vibration?
If it wobbles:
Take a look at the wheel and see if it can move bend from side to side when you use your hands. It should be nice and stiff with no play.
If it bends a bit and you have the tools, tighten it up. If it is tight but still wobbles, take the wheel out and check the clearance between the bearing and the wheel, it should be a nice tight fit. If it isn't you might need a replacement wheel.
If it vibrates:
It's most likely a flat spot on the wheel. The alternative is the wheel is out of round, if the wheel is new it might have been made like that (poor QC).