The tire sidewall numbers will show maximum inflation and possibly another pressure with an associated load rating.
The door sticker will show manufacturers recommended pressure, for the OEM tires. I think it is a bit low for spirited driving and maximum tire life, but great for the smoothest ride. The newer (replacement) tires come with higher and higher max pressure ratings. They tend to bulge less, hence wear in the center less than the old bias ply tires. The higher pressures roll easier, for better fuel economy and less heat build-up and allow higher loads. Fifty seems rather high and would certainly deliver a hard ride and probably less than optimum tire life. On my original Gatorbacks, I repeated saw 35k+ of tire life which was about 75% more than tire dealers normally saw on Vettes.
There will be a variance in opinions, so you'll have to experiment and find what pressure works best for your driving patterns and ride preferences. I run close to the tire's maximum which has always delivered great tire life and minimal sidewall flex, but a harsher ride. Inflate, drive and see how the tire responds and how harsh it rides. Longer term, keep an eye on your wear patterns and adjust as best you can for more even wear. FWIW, I am now running 40+/- (high for this group).
Kumhos (Korean brand, I believe), as far as I know, were never OEM tires on any Vette.
