How to choose spring rates. Getting your spring rates to a sensible starting point for you car and application is something we all struggle with when starting out. This lesson, taken directly from the Suspension Tuning and Optimisation course, will hopefully help make it a little bit easier for you. Using a mechanically biased RWD road legal circuit car for the example, Tim runs though the calculations used to work out our spring rates for the front and rear of the car noting along the way some