I purchased a 2017 i-MiEV earlier this year and have been trying to find an extra set of wheels for snow tires. I've done a bunch of reading in this forum and others. I read that that the front centre bore is 56.1mm, but it can be reduced to 54.1mm (to match the rear) if the pressed in collar is removed. Based on this, I purchased a set of 15x5 54.1mm centre bore alloys from a Prius c. They're 39mm offset instead of 35mm, but my hope is that they'll be close enough. If a 4mm spacer is required, then I'm again hoping that it wouldn't be so much as to require pressing in longer studs.
The Prius c alloys mount on the rear nicely as expected, but, even with the collar removed, they won't mount on the front. The collar is actually a smaller diameter than the hub. The hub isn't the same diameter the whole way back to the rotor and gets smaller close to the rotor. It's hard to measure it due to the studs, but I think it's 54.1mm close to the rotor.
Does anyone know if there was a change in the later years of production for the front hub? Any suggestions on fitting these wheels to the front?
In case it helps anyone, I noticed that the lug nuts on the i-MiEV aren't compatible with the Prius c wheels. I picked up a new set of lug nuts from the local Toyota dealer. The Prius c are a "mag" style, but the ones on my i-MiEV with the factory alloys are cone.
Another thing that others may find helpful to know is that Tirerack has OEM fitment "Radius" wheels for the i-MiEV right now. They are 15x5/35mm offset/54.1mm centre bore and 15x4/35mm offset/56.1mm centre bore. The centre bores aren't listed on the site, but I emailed Tirerack support and they confirmed they are the correct bore. I didn't go this route because I'm in Canada and the cost is quite high to get them into the country. I also like the look of the Prius c wheels more.