F-60 Polyglas date code

[GY3R/T]

   Looking at a set of "advertized" 70-71 Goodyear F 60 15" Polyglas tires. Guy says he removed them from his 1971 Chivell in 71.    They are in "like new" condition.  Date code has me kinda confused. Letters don't jive with dates & assm. plants that i know of... AND seqence is awfully long.
Here's the code;   CYUDB4GG2500      Could the 2500 be 25th week of yr.2000 ?  Any help would be appreciated.

[6bblgt]

modern reproductions

CY = plant = McCreary Tire in Indiana, PA
UDB = size =
4GG = type =
2500 = date = 25th week of '00

[RUNCHARGER]

Oooh: Date code matches the value.

[GY3R/T]

   Thank You @6bblgt !