How do you go about finding that out?
I use Shimano 550's as training wheels and have no idea what the recommended max is as I like a high psi.
You'd have to check with the manufacturer. Most do not seem to readily list the max pressures. I have seen them a few times. With those 550s you'll have more to worry about than sidewall failures anyway. Keep an eye out for spokes breaking - have a backup plan.
Again this goes into what pressure to run them at. As pointed out in that example you should never be running the tires at 145 anyway. Run them at the appropriate pressure for your weight. If the appropriate pressure is around 145 then step up to wider tires and/or lose some weight.