I've tried the search button but there is little info regarding this topic. I'm looking to get some coils (BC Racing - ISC if the 250/350 are compatible w/200t) So from the search the standard spring rates from BC Racing are 12k/10k but I see that other people have gone 10k/12k and 12k/8k (perhaps even other rates). So for those who know a bit more on this topic, how do you properly chose spring rates? What do you have to consider?

I guess the lower you plan to go the stiffer (higher rates) you want it, but what criteria do you use? A 0.5" drop go with XX rates or a 1" drop go with YY rates. etc.

 

Each manufacturer decides on how aggressive the spring rates and damping and/or rebound their shocks; based on R&D to what their preferences for those cars. So at the end, it's the same for you when you decide which one you want based on what your goals are for the car. There are no special formula by the book.

stiffer spring and shocks are not always the best thing.. but typically speaking, all after market coilover systems will be stiffer than stock... if you want a mild drop for reducing wheel gaps (looks) only, select a coil over set with lower spring rates (as close to stock as possible) and you will not loose too much comfort.

- if you want to slam your car and be part of the camber-gang, you want something as stiff as possible since you don't have much suspension travel.
- if you want to track your car or want a significant upgrade due to your spirited driving style, you want to do more research and consider how much stiffer to suit your taste.

 

I just want to get reduce the wheel gap, but what's strange is that I emailed BC Racing regarding the spring rates and they told me "We would not deter from the stock rates that these come with if you want a comfortable, OE style ride" but that statement is somewhat vague cause it doesn't mention anything about the drop so the proper spring rate can be selected to prevent bottoming out. I will be emailing them to see if I can get a better answer, but in the meantime I wanted to know why people went with custom rates, but so far nobody with custom rates have replied.