Inflate the tire, let the air out again, and inflate it again. This is a trick I learned from my brother Mark. It makes the tube and tire shift around and get evenly seated around the rim.
Then you can let it sit around for a while to see if it holds air. If you're in a hurry to know for sure, put it in the dunk tank. Alison Murphy tests a tire in 2007 by dunking it in the waterjet cutter. As soon as we did this I regretted it because of abrasives in the tank, but it caused no apparent harm to the brakes or hub.