🔧 Spring Rate
How stiff a shock spring is — the force needed to compress it a given distance.
Softer springs generally give more grip and more body roll; stiffer springs give quicker response and less roll. Brands colour-code their springs, but the colours are not standardised between brands — check the rate on the packet, not the colour.
What it actually does
Spring rate is how much force it takes to compress a spring by a given amount — how stiff it is. Springs decide how far the car moves and how much weight transfers; the shock oil then decides how fast that movement happens. The two are always tuned together.
In practice
Stiffer springs reduce body roll and squat and suit high-grip, smooth surfaces. Softer springs let the suspension follow rough ground and generally find more grip on loose surfaces. Manufacturers colour-code springs, but the codes are not consistent between brands.
Worth knowing
Change springs at one end at a time. Changing all four at once tells you the car is different but not why, and you lose the ability to reason about front-to-rear balance.