I could be completely wrong, but I believe the main difference between multipiece wheels and single piece is that the latter are drop center type, allowing for easier tire installation. Most multipiece wheels are flat across the wheel and the split rim comes off to allow the tire to slide over the cylindrical part of the wheel. So for the same diameter wheel, the center section may be smaller where it welds to to a single piece rim.
Welding up a multipiece wheel probably won't work very well for mounting tires.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.