[Dimis]

Angle Grinder. Lol. No, just kidding.

Butane torch and heat the metal
That will help "stretch" it a little, then blast it with some antiseize like WD-40 and begin negotiations using a hammer and price of timber to prevent damaging the wheel.

I find and copious amounts of swearing seems to help ones emotional state while undertaking such proceedings.

Ps. If you get frustrated with it walk away for a few moments... and then revisit it again after a spell.

This little sucker won't beat you!