On rigs that see a combination of highway and trail time where we air up and down on a regular basis, we sometimes add a second valve stem 180 degrees from the original valve stem. However, for the second stem we use a two-piece tractor or grader stem. These come straight or angled, and have a stem core that can be pulled to expose a large orifice which releases the air very rapidly. Whenever we go to air down using these valves there’s almost always someone commenting about the loud air escape as if we just jabbed our camping knife into a tire sidewall. Simply put, these things get the air out fast. And in our experience we’ve not had one leak at the added o-ring-sealed fitting. They do require drilling a 5/8-inch hole somewhere on your wheel to add the stem, but that’s a pretty simple process.