Whilst you could disassemble a wheel to remove a tyre, the purpose of a split rim is the interchangeability of centres and rims to be able to mix and match styles, widths and offsets. Reassembling a split rim wheel inside a new tyre would be virtually impossible. The bolts need to be torqued in sequence and the force required to locate the tyre with the first couple of bolts would be immense, even if the bolts are long enough to reach.