I go with Darren on this one. With some serious vintage racing in both my old 275 GTB Ferrari with HARD Michelin tires, and the same with my Alfa with SOFT Bridgstones, I resorted to the days when I really (tried) to race. I would use a tire pyrometer (modern electric, digital, non-contact) and measure heat across the thread after some hard driving. The idea was to find a HOT pressure that caused even heat across the tread, WITHOUT the tread chunking, or tearing away in little pieces at the edges. THAT was my racing pressure. Letting things cool down, that happened to be 33 lbs front AND rear on the Ferrari, cold. The Alfa is different. I use that same pressure with the Ferrari on the street, though it is not ideal with a cold tire, or on a cool day. When hot, the Michelins seem to have maximum grip at this pressure, and do not come apart.
My gauge is an old racing DRAGER. I generally over inflate, and bleed down to my desired pressure. Both the Alfa and Ferrari use valve stem supports to avoid the valve stems flexing around from centrifugal force at speed. I use TUBES in my tubless tires on tube type rims. Tubes do cause the tires to run hotter than without, but wheel design, Minilite magnesium on the Alfa, and wire wheels on the Ferrari, both designed for tube type tires, makes good tubes a safety issue.
Well ... that was a LONG answer to a short question! I hope it helps, Simon. This is from my experience.