I do like that they are trying to do more one-piece wheels now, but this is certainly annoying. Aoshima, Fujimi, and Tamiya figured it out ages ago that a single wheel that slides in the back is the best, since it is see-through (no wheel backs), easy to put in tires that have a slightly smaller opening, and means you don't have to bother with finding wheel backs that fit when using extra wheels from kit on another.