The clubs I have raced at here in the states have tire reps from most tire manufactures. Dunlop, Michelin, Pirelli, Bridgestone. And Ye, Ive been to track days where they are there as well, mostly track days that bump up against race weekends.

About the tire rep knowing about what pressure to use for a tire on a bike? They have a pretty good idea, even for something odd like an NSR250. Trust me, it's not like these things are some super secret motorcycle

If they don't show up at the track, you can still call them for support on their product
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Charles Gallant