My understanding was that PL5 was the standard white lettered (ss/copo)tire in 1969 and PL4 was the optional Polyglas. I have never seen a polyglas on a 69 car but mention is made on the released ZL1 documents regarding car #68 being so equipped. Were there any 15 inch polyglas tires available for 9737 equipped cars or Z28's, and what was the code. You would think, cars designed with handling in mind would have the polyglas tires available.
BTW, this is a great informative thread... keep up the great work
