what should the tire pressure be for bridge stone 4.5/10.0-5?

That really depends on what class of Kart, and the weather and LOTS of other factors... Do you want cold pressures (on the grid) or hot pressures (Just off the track)
IF its on a Kid kart and you're in a racing situation, there is a maximum HOT pressure rule. Your club can tell you the pressure.
For most cadets, jrs and Sr's start around 12-15 lbs and see what that does for you.
With Kid Karts you may need to start higher.
We've used everyhwere from 8 lbs to 22 lbs....
But 95% of the time are betweeen 10 and 15 lbs (on everything but kid Karts)
OH I forgot one thing..WHICH Bridgestone...YHC? or the new YKC?

thanks for the post, it was very helpful.
I have YGk.