A siezed wheel can be removed quite easily by wrapping a towel around the centre portion and the roots of the spokes, then slowly pouring almost boiling water over the towel. This will hold the heat while it is passed into the wheel. As aready suggested, clean the mounting spigot and the wheel centre bore before giving them a thin coat of Copaslip. I also use Copaslip on the wheel bolt threads and taper, and then tighten with one hand - NOT a torque wrench! In about 60 years I have never had a wheel bolt come loose - no matter what the prophets of doom will say!