Changing a Flat, getting wheel off

[sames1]

It's late and I didn't want to mess with it in the dark too long, but we had a flat tonight on our 2005 X5 with 19" wheels. I took off all the lug nuts but could not make the wheel budge. Is there something else holding it there or do I just need to use more force? The manual didn't seem to help and much and a Google search provided little info.

Yes it was clear of the ground. I took off the center BMW cap and it looks like a locking nut of some type but I don't know if that comes off or even if I have a tool for it.

Sorry if this is basic, I don't do this much.