Hello. I recently purchased a 60s Sting Ray and a few parts. One of the parts was a USA made Carlisle Knobby Slik with "Schwinn Sting Ray" raised letter logos. The tire date code is C 11 7 2 with (11 7) in an oval. This seems to date the tire to 1967. My question is what Sting Ray bikes had these tires as stock? I've heard the early 1968 Krates had knobby slik tires, but I believe thay all had a color line matching the paint. It seems that the black wall knobby sliks didn't last long on production bikes. Any help would be appreciated!