On the iMiEV, the front spindles have a pressed on steel collar whose only function it to make sure some idiot doesn't try bolting a rear wheel on the front - The collar makes the front centerbore need to be larger than it is for the rear wheels
If the I wheels you buy all have the smaller centerbore, you can pull that collar off the front spindles - They are just pressed in. Once the collar is removed, the smaller centerbore wheels will fit. Drilling a pair of small holes in the collars so you can stick a small phillips screwdriver through the holes gives you something to yank on to pull the collars off. They just tap back on with a mallet if you need to put them back on. If you're the only one removing and reinstalling the wheels on your car, there's no reason to put them back on. I think they're just there to prevent someone unfamiliar with the car from bolting a rear wheel on the front . . . . the wheel wouldn't turn anyway if someone did, but tire store employees aren't always that observant . . . .
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