Are 20x3 wheels hard to get?

My friend has the XP 3.0 and his wheel wobbles enough to be making the brake rotor touch the pads and make a constant squeaking sound(at least that's my suspicion) I looked for 20x3 wheels (front) and only found a few. Seems Ike the tires are common enough but not the wheel. Anyone know how I can get my hands on one? (Front) Or have any solution on the squealing?