To prevent cross-threading, rotate the nut counter-clockwise until you feel the end of the nut's thread fall over the end thread of the bolt. Then, turn clockwise to tighten.

Do not over tighten nuts!  Tighten only until firmly snug.  This is especially important when working with plastic skis.  They always have a cushioned feel to them, unlike steel skis which provide a dead stop to the nut. We use 5/16" x 18 bolts because these are all that is necessary - strength-wise. Having more than one bolt only helps keep the host bar straight. Also, this allows the easiest installation without any need to drill the skis or use a hammer. It is not the size of the bolts, but the number and location that is important. Easy installation