YASA beats own power density record pushing electric motor to 59kW/kg benchmark

At what point can we just return to 1990s wheel sizes, add the motor to the wheel, and have the same unsprung mass as we have with today's gigantic wheels?

Putting the motor in the wheel does have some performance and space advantages. It is being done in some vehicles today.

However it does have some limitations as well. For the "general case" it may not be ideal.

Top of the list is protection. The motor is an expensive part, the wheel is an exposed part - bumping a curb for example could get expensive quickly.

Cooling is also an issue. In-wheel motors suggest air cooling, whereas a bigger (single) motor can be liquid cooled.

Currently in wheel motors end up being quite a bit more expensive (because 4 motors not 1).

On paper, in-wheel motors save space, allow for concepts like "4 wheel drive with different lock", save weight and cleaner design (no drive shafts etc), but it's not clear that the end product is better for "every day" users.

I want rear wheel steering with 7m turning radius, 4m cars to have same cabin space as 4.5m ICE cars, seats in last row of a 3-row not constrained why wheel wells and axles as an Indian on congested roads. 160 HP is dangerous enough.

As soon as the roads are as smooth as they were in the 90s. I have a pet theory that wheels have gotten huge partly in response to deteriorating roads - larger diameter means less leverage against the suspension when hitting defects. It’s the same reason dirt bikes have large front wheels.

The aspect ratio (sidewall height) of tires has decreased in a lot of vehicles though. They are driving around with low profile rubber bands on the rims. Looks cool, but not much fun in the potholed mid-west.

Elaph and Protean are the well known in-wheel-motor producers now and some other companies have done in-house versions.

That teardrop-shaped EV [Ed: Aptera] was going to use the Elaph ones but I think there was some issue with producing enough of them or something like that.

Protean wheels will be on the new Renault 5 Turbo3E which will be a high performance, expensive, short production run.

They make it "easy" to electrify a petrol car and there's a few Sandy Munro videos about the Protean wheels where they test drive a Mercedes converted to and EV with them. Munro was contracted to find ways to get the manufacturing cost down without reducing the durability too much.

You might think that YASA motors would be extra useful for IWM applications where lightness is important but there are other constraints such as durability and fitting in the electronics and it might be essential to have a completely custom design. I don't really know but I do think they should be working together in an ideal world.

They are apparently getting the cost down to where we might start to see them in more affordable vehicles: https://www.proteanelectric.com/protean-showcasing-iwm-techn...

After he destroyed his 3rd ultra-low-aspect tire in one year, my dad got smaller wheels for his Golf R.

motors do not like the impact loads that wheels see, which is why bicycles with hub motors do not have a long lifespan