According to Hotchkis, the stock spring rates for the tC are:

Front - 150 lbs/in
Rear - 245 lbs/in

TRD says that their springs are 18% and 26% stiffer (Front/Rear)

So TRD =

Front - 177lbs/in
Rear - 308 lbs/in

...In case anyone was interested.

- Dante

 

Lol. My fiance always complains about how rough the ride is in my car compared to her Taurus. I just tell her, "wait till I get the TRD springs...the ride will be much harder then". She just rolls her eyes. I want TRD springs.

 

TRDs do not feel stiff to me - if you are used to a 'nice' feeling car Japanese/German etc they all feel stiffer than a Taurus - they are sloppy feeling.