One engineers approach, Make the leak larger and easier to find by reducing molecule size.

If the leak is almost impossible to find, consider putting helium into the air system rather than air. The helium won’t hurt anything on the suspension; but will leak more than 10 times faster for the same size hole and pressure. Helium is readily available at most party stores for inflating children’s balloons. The reason is simply the molecule size. A helium balloon shrinks because the gas molecules within the balloon can slowly pass directly through the permeable rubber of the balloon, air does not. Tires also have a permeability ratio that will allow them to very slowly deflate. A helium molecule may be the smallest molecule in existence. A carbon dioxide molecule (Air) is much larger, composed of one carbon atom and two oxygen atoms.

Remove the helium before driving the bus.