Inner tubes perform best when they are able to hold air. I came to this brilliant conclusion the first time I got a flat. Sometimes pinch flats are unavoidable, even when running heavy-duty inner tubes. But a tear where the valve stem meets the tube is often the result of the tube shifting slightly and the stem refusing to budge. Riding off road increases these odds. If you leave the valve stem nut at the halfway point, many times a flat can be avoided. Yes, this might also encourage the tube to shift slightly, but ask yourself what’s more inconvenient: having to pull your wheel off at home to straighten the tube, or having a unrepairable flat out in the middle of nowhere.