Spring rates for various springs available for the JZA80 Supra:

Specs are in lbs/in.  Listed in order from softest to stiffest. 

Manf.           Type                     Front           Rear
--------------- -------------------      -----------     ------------
Stock           linear                    430             219
Eibach          progressive               370-->510       180-->263
H&R             progressive/linear        470-->495       250
Intrax          progressive               559             285
HKS Super Form  progressive               366-->597       209-->245
HKS 10-way*     coilover                  661             386
HKS 20-way*     coilover                  661             386
HKS 30-way      coilover                  772             441
HKS Drag        coilover                  772             220
Tein            coilover                  780             450
Intrax          coilover                   ?               ? 
Grnd Cntrl      coilover                  950             600



* HKS has discontinued the softer 10way and 20way coil-overs.  

Thanks to Kent Rafferty for starting out this spreadsheet.
Thanks to Dusty Womack for getting the HKS coilover spring rates. 
Thanks to Ed Kenyon for the HKS Super Form spring rates. 

Edited by Andi Baritchi. 

Boostaholic.com.