C 43 1
C is Carlisle tire company, 4 is April, 3 is '73. Nobody knows what that last digit means, I've seen 1 - 3 on tires
Looks like a blackwall Gripper Slik to me, however, your 69 Krate would have used the color line version - what Krate do you own? Pea would have been green, Lemon would have been yellow, etc.
Original date coded color lines are expensive if you can find them. You can get a nice repro version for around $100-$125, look on Ebay, BicycleBones typically has them and maybe even Scott here from the CABE