I am looking for aftermarket wheels too. I ordered an ATS with 17-inch wheels and I understand that they are 5 x 120, but I do not know offset. I obtained the info from www.hubcaphaven.com/cadillac/ATS factory wheels, Cadillac part 9598563. Niche wheels are being offered through D3 elsewhere in these forums. You could check with them. If you find a cool aftermarket wheel, show us some pix!The factory wheels are 5x115 bolt pattern. Offset is 42mm.