Wondering if the rear sprocket carriers are interchangeable between a 2002 S4 and a 2003 800S....
S4 would have been a 525 chain, 800 a 520. Nt sure if that makes a difference in the carrier but I'd think it would.
800 - 160.1.049.1B
S4 - 160.1.049.1A
Pretty sure the S4 unit will have the rear sprocket mounted further outboard.
Your rear rim/tire are 4.50 / 160/60-17, yes?
Upon closer inspection, they are indeed different. I'm assuming the one on the left would be for the S4, and the one on the right for the 800, based on what speeddog said about the sprocket being further outboard of the wheel. (https://lh6.googleusercontent.com/-UbdQUji7E2U/T6hvuYOotvI/AAAAAAAAYQs/4qnP_DWKszU/s912/2012-05-07.jpg)
Makes sense...
Maybe it's just the angles - but the threaded posts look bigger too.