numbers stamped on the coilover?
How do I tell what my spring rates are?
Ground Control sells Eibach Race Springs (ERS) which are labelled by 3 different values in the following convention: length . diameter . spring rate. However, ERS will come labelled in either Metric (mm.mm.N/m) or English (inchx100.inchx100.lbs/inch) units. 180.64.61 is the same thing as 700.250.350. The conversion from Metric to English is (/.254, /.254, x5.7) "/" means "divide by", "x" means "multiply by".
The math is simple. If K= Spring Rate, then K = (G(d/1000)^4) / (8Na(D/1000)^3), that will tell you your spring rate.