A ride probably. On the bike itself and on a train with it. I'd really like it to work, but if air filled tyres are still the best for any bike, I assume non air tyres are quite a compromise. I really llke thinking outside the box, but wheels are pretty essential to the ride, you really want play in that? One important quality of the wheel is that it's round and spreads all the forces over it's integral structure, you really want to sacrifice that quality for foldability? What degree of precision engineering and machining do you need to make it work and will it hold up to daily use? Or will any dent or dirt getting in a mechanism stop it from functioning and make it useless? Is a foldable big wheel better than a solid small wheel? Basically all bikes are simple sturdy contraptions, that's what makes them work so beautifully, take some abuse and what gives us sensory feedback that makes them easy to ride.

A folding bike is always a compromise, the question is what do you want to have compromised. The rigidity of the frame, the size of the wheels, the drive chain, the foldabiltiy and compactness, but the wheel itself wouldn't be my first choice. But it depends on the intended use, if you want to take it on the bus and tram and do small errands from there it should be handluggage size and weight and maybe not be a bike at all. If you take it on a train to do 10km of cycling it just needs to fit in the luggage space. I own a non folding compact bike that's a pretty good ride because the frame is rigid, maybe with a few minor changes it could be made suitable for that luggage space. You could also design the best riding bike possible that would still fit in a specific luggage space, and not make it foldable, that's thinking outside of the box too. I believe a folder or any compact bike should be compact enough for it's use, not as compact as possible. If two of them fit in the boot of a medium sized car for example, should it be any more compact at the expense of the ride? Should it be any more compact at the expense of easy handling the package? Is folding into a cube shape really more practical than a longer and narrower package?

I designed a folding bike once, just a sketch for the fun of it. It was quite creative because it was basically a unicycle with a small support and steering wheel trailing and a laid back riding position. When folded you could just pull it by the saddle with the wheel rolling and use it as shopping trolley. But then a friend who worked at an LBS for extremely sturdy used single speeds scrutinized it and to make it work it would need high tech, heavy metal and precision engineering.and probably another groundbreaking innovation or two. I don't want to compare my sketch to professional designers and engineer's work, but often in bike design we see one groundbraking idea, a eureka moment probably, that is hung on to because of it's charm through all the compromises in the rest of the bike necessary to make it work.