EBay.
http://www.ebay.com/itm/230993705953
First issue: the inner diameter just barely touches at the corner on the stock 10-1/2 front rotor hubs and will need to be filed about 1/8" at a 60-degree angle - I'll probably turn them on a lathe at work unless I get the S-10 knuckles installed first. These have a totally different profile and will have no issues.
Second issue: the 2010 Camaro uses M14x1.5 studs instead of the G-body M12x1.5 studs. I thought I might press out the studs and redrill for the larger lugs - a box of 20 from RockAuto is only $20 - in order to use the stock lug nuts that came with my rims. However, when I looked up the company a few minutes ago to copy the link, they now offer lug nuts to make these work with Camaro rims. I sent them a message and I will post their reply when it comes in.
Before you slam 'crappy' EBay mystery products: when I put these on the Malibu, I had no issues (at all) with the lugs staying tight. I bought a pair of Cal Custom bolt-on adapters from Summit for twice the price three years ago and I had to keep tightening them for days because the studs were barely pressed in. Fortunately I never lost a wheel. (They finally seated, and I've had no issues since then.)
The tires are 235/45/18. Found locally on Craigslist for $100. These are 26.3 inches in diameter, just a tiny bit larger than the stock 195/75/14s. Data from Tire Rack suggests that this is the largest width tire recommended for these 7-1/2 inch wide rims.