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I know that the width difference might present problems later on, but if I understand correctly then it should be possible. The bike isn't meant to be used in high performance circumstances, just the city.
However, if I understand correctly, the tire would have a larger diameter than the rim. Is that likely to cause me much trouble?
tl;dr If I have a 32-630 tire and a 20-622 rim, can I make the combination work?
No. The bead seat diameter (inner diameter) is different by 8 mm. You cannot shrink a steel or Kevlar bead by 8mm, as they are designed not to stretch or shrink (otherwise a clincher tire will roll off the rim in a corner). You can try but the tube will burst out from the extra space.
The tire bead is what interfaces with the rim.
