Hello Don!
If you still want some answers to your questions, I can supply you with a few.
700c is an old French standard. It’s equal to ISO 622 which is the diameter in mm of the bead seat of the rim. 60 is the width of the tyre in mm but it can vary a bit depending on the width of the rim. A wider rim gives a wider tyre. The width of the tyre should be approximately 1.45 – 2.0 x the inner width of the rim, but that’s only a general guideline. My new bike, which I’m going to convert with a Magic Pie, has a 24 x 3” rear tyre fit on a 32 mm wide rim though. (75 / 32 = 2.34) So Schwalbe’s 60 mm tyre could probably be fitted on a 26 mm wide rim.
What is the width of your rim?
If the rim width on the 24” Magic Pie is to narrow, I’ll replace the rim to a wider one. Hope to find a double walled 24” rim wider than 32 mm because the original looks a little to narrow for the 3” tyre.
Best regards
Peter