Interesting Marking on Original Speedway Tire

I am guessing someone decided that having "GT350" tires on a big block might cause some confusion?

 

I was talking to John Kelsey of Kelsey tires about a Goodyear Polyglas black wall tire where we were discussing the molds. Our discussion had to do with lettering that was on some early tires that weren't on some later tires. Even though we were not talking about the Speedways the information seems to be the same and apply to this discussion. John said that Goodyear typically had several molds to do tires so as tires were curing molds could be poured etc. and that modifying the molds as needed was the norm. In the speedway case The GT letters may have been taken out of the mold but not completely enough. No doubt the undesirable effect was noticed and the mold modified further to completely get rid of the GT letters. That is the simplist explanation based on John Kelseys description.