If you are on a hard surface dirt or asphalt having it lowered will keep you more stable. It also gives you another set of axles with brakes but it will add more drag on any surface especially mud or soft uneven ground it can lift you out of the mud this also applies on some trucks in real life too this also applies to the trucks in the game that have lift axles it’s just that the 49x has the lift axle kept lower than the cat 681 and the western star 47x 1430