Going to be a pretty standard 60m Ferris Wheel sold by Dutch Wheels which is Vekoma's giant wheel division. I imagine like all the rest it will be fabricated by Chance. It will be one of the 2 on the right at the bottom of this page...
http://www.dutchwheels.com/index.php/products/dw-seriesand he're a picture of their first DW60 wheel, this is the 60/30, Navy Pier will get the 60/42, same basic wheel, just more gondolas
Favorite Wood Coasters: The Voyage, Ravine Flyer II, Thunderhead, Balder
Favorite Steel: Steel Vengeance, Expedition GeForce, Olympia Looping
Parks visited: 222, Coasters Ridden: Steel: 822, Wood: 178, Total: 1000