Spring Rate Conversion, kg/mm to lb/in
 

Kg/mm = Lb/in
16 = 896
15 = 840
14 = 784
13 = 728
12 = 672
11 = 616
10 = 560
9.0 = 504
8.5 = 476
8.0 = 448
7.5 = 420
7.0 = 392
6.5 = 364
6.0 = 336
5.5 = 308
5.0 = 280
4.5 = 252
4.0 = 224
3.0 = 168
2.0 = 112

Spec Miata SCCA 1.8 NA/NB Spring Rates:
Springs br /> FFront Eibach ERS 700 lbs/6” 0000-04-9700-06
Rear Eibach ERS 325 lbs/7” 0000-04-9325-07