Herbie
Rendezvous Conspirator
What do these rim/tire weigh?
How often will you use them?
Would you carry these with you on your travels full time?
From what I've seen of the folks that use them: The weight isn't much of a concern, because they do NOT carry them full time. They're used for the shipping evolution, then generally stored or shipped overland separately to someplace near the final-destination so that they can be re-used for return journey after a (presumably) long travel period. These kinds of things make the most sense for the big trans-Pacific or trans-Atlantic shipments. Once could foresee using such things to get from North America to Europe, then storing them in Europe while travelling all of Europe and Africa (depending on route through Africa, possible to do drive-on Ferries for these legs.), and then refitting the shipping kit for the return to North America.
Yes, both the "manhole cover" and "spare mini-wheels" solutions do cost some money, but given that going from standard 20' container to a 40' High-Cube is a big jump in price, and going RORO also adds significant cost (AND introduces security concerns, etc.), it still could be cheaper to spend money on single- or two-use items versus just surrendering to the problem.