The best place to start is by having an inspection done at a tire and alignment shop. They will check for a bent wheel, broken belt in a tire, and out-of-balance tires along with the steering and suspension components. You will not feel an out-of-balance tire at lower speeds such as in-town driving. You WILL usually feel a broken tire belt at low speed. Watch for the steering wheel moving back and forth a little while driving through a parking lot.