They are available in the USA for $465 in size 16 X 5.5 and $475 for 16 X 6.0. I didn't see any 17's narrower than 6.0 and I really doubt that the Rinspeed iMiEV is actually wearing 17's - They sure don't look THAT big to me . . . .
Four of the 16 X 5.5's wearing the same size tire would be a great upgrade, IMO - Considering that the factory wheels are only 4 inches wide in front and 5 inches in the rear . . . . no real need to go to 6 inch wheels
One downside is of course that you're never going to find any LRR's (Low Rolling Resistance tires) in those sizes . . . . but then I seriously doubt that the folks at Rinspeed are at all worried about the reduction in range these wheels/tires probably cause - Sticky, great handling tires are on the opposite end of the tire spectrum from LRR's. Small price to pay for the big increase in handling
2012 iMiEV SE Premium, White
2012 iMiEV SE, White
2014 Ford Transit Connect XLT SWB wagon, 14,000 miles
1994 Miata 60K miles - Soon to be sold
1979 Honda CBX six into six