Interested Observer, I was imagining the outer rim being approximately 1/2" thick, made of a relatively high-strength steel with good toughness. Type 4340 steel comes to
mind. It's used for gun barrels and helicopter main rotor shafts, because it is resistant to developing cracks.
You asked good questions. I'll try to answer them in order.
1. The rim would have a "T-shaped" cross section, and have a central rib that "protrudes" inward toward the center. That rib would be contained in a groove incorporated into the design of the hub, which would be comprised of 2 round pieces, each with a step, bolted together. This is to allow the hub to be assembled around the one-piece rim. Since the groove of the hub assembly would "contain" the rim, layers of fluid would need to keep the rim from moving very far either "outboard" or "inboard", direction-wise, on the hub. The fluid would be dispensed through pathways (pretty much radial, perhaps) in the hub. But I also believe that many pathways for the fluid would each have to be separately controlled, to keep the rim from rubbing ANYWHERE on the hub. Not easy. I envision the fluid layer being about .001" thick everywhere it exists, and being under
a pretty good amount of pressure until it escapes from the hub/rim assembly.
2. Braking would mainly be provided by air brakes mounted in the fuselage (like on jet fighter aircraft), parachutes, and perhaps by a skid that rubs on the ground. Breedlove's car had a skid. The outer rim of each wheel could also be braked, but that's another big challenge. None of this would be easy!
3. I'm visualizing an extremely thin layer of fluid everywhere between the rim and the hub. And of course, lots and lots of laboratory testing would be necessary before trying any of this on a vehicle. The testing would have to be done while simulating the weight of the vehicle resting on the ground. The testing would be done with various fluids
and all the various parameters would need to be developed, such as flow rate, pressure, etc. I visualize a relatively non-polluting fluid, but have also considered carbon dioxide for this. So far, I'm leaning toward plain old water. Yeah, it's heavy. But it also can soak up a lot of heat while phase-changing. The vehicle might need to carry about a hundred gallons or more. If brine is used, it could be quite cold at the start of the run.
4. The main reason for this design is not to improve bearings. It's to accommodate a lightweight rim that won't fly apart at high RPM.
5. All these things would have to be developed, with a lot of testing included. Huge-bucks stuff!
6. I second that etc., etc. motion. It doesn't cost much to think/dream about future technology. Stuff like that doesn't become reality until after someone has given it
enough thought, followed by a lot of effort and money. I get it. And yes, I'm not suggesting this will happen anytime soon. Even if I were wealthy, I wouldn't try to develop
the technology unless somebody wanted it badly enough to pay for it. And yes, the world does not absolutely NEED a 1,200 mph land speed car. Agreed?