I love these new designer LEGO sets, but I wish that all of their parts would be available in LEGO CAD already! So... 1. Part 32040 should be the small grey steering wheel in the set. 2. The smaller wheels are used for the front 8 wheels. The larger wheels are used for the rear 4 wheels on the pivoting parts and the 'spare' on the far back. Send me feedback! Jason ( jello_hd@hotmail.com ) Just make sure you mention LEGO in the subject so I don't miss it.