You would be amazed at how many people get stuck in the sand and snow due to too much air pressure. Dropping your rig into the 10- to 12-pound range can mean the difference in getting out or going down. Another important wheel tip is to be mindful of your valve stem. Many late-model 4x4s are equipped with steel TPMS (Tire Pressure Monitoring Sensors) that thread into the wheel. Unlike a traditional valve stem that has a bit of give and flex, the steel sensors will often break when they encounter an obstacle.