The tires we run on these buses are engineered with an *ENORMOUS* safety factor. Granted, split rims aren't without their risks, but once safely mounted on a bus, the likelihood of anything happening during a routine tire pressure check is extremely unlikely. Same holds true for the tires themselves. If one is likely to fail, it is likely to do so upon its first inflation.
These are designed to withstand high pressures, a tremendous amount of beating from rough roads, hot pavement, frigid conditions, and countless other factors. So checking pressures while at rest is not likely to cause a sudden rupture.