The rear springs are a matter of how much lift and your preference for carrying capacity over ride quality. The standard rate rears are around 150lbs. They'll give a good ride with a fair carrying ability. If you need mor weight capacity in the future it's a simple matter of installing some Airlift bags in the coils later. The standard Calmini rear coils for their 3" lift are pretty good and I believe are near the same rate only longer. Keep in mind that under most circumstances the springs will soften over time, in fact I've worn out and sagged 3 sets of front Calmini coils in 4 years of wheeling. With the added weight of a winch and steel bumper among other accessories they start out nice and firm, soften up to give great flex and a nice ride and eventually soften to the point of sagging and loosing lift. I've finally given up on them and am going to be installing a slightly heavier rate coil, 600lb and a inch longer than the Calmini's.