I used the WD40 method and offer one warning: go carefully and only use a little bit at a time. It softens the glue, but it also softens the plastic in the wheel. I cracked one road wheel. I've glued it back to together and drilled out the wheel bolts to use 0-80 screws and nuts to hold the wheels together instead of glue. So, we'll see how that works.
Key is that the two wheels are glued into each other via a flange on the inner wheel that extends into the outer wheel. Or, is it the other way around? I forget. FV432's Bulldog build has some more tips for this.