Need help figuring my spring rates

I bought a car that was already set up. The seller didn't seem to know the spring rates in the car and I am trying to figure them out for myself.

Relevant information:
This is a 4th gen Firebird with Ground Control Coilovers on the front. The rears have a threaded lower perch for the coil to sit in and the piece looks similar in color scheme as the front GC kits.

I just jacked the car up and looked...

The front springs are labeled Eibach and have the following numbers painted on them: 0800.250.0850 Are any of these numbers indicating the spring rate. There are no other markings on the springs.

The rears are completely unmarked gray, steel coils. Top-to-bottom, they are 9.25" tall...

Any ideas?

The numbers for the front mean it's an 8" long, 2.5" ID spring. The last number is the rate, 850 #/in.

No way to tell what the rears are without some detailed measurements.

Keith, Jon's right about the front spring rates. Damn, that's a Global West type of spring rate. Thinking about using that 35mm sway bar on the front of this car too?

My rear springs also don't have a rate on them. I don't think any of them do. Luckily I bought mine from a local autoxer that had them in the original boxes. You could always measure the free height, then set a known weight on top of one of them and measure how much it compresses. Not sure there's much else you can do.

I figured these were stiff springs.

This has caused me conclude that I should call the previous, previous owner today. I have a couple of other questions about the car and he clearly was the one who did the setup, etc.

I posted the spring rate equation in your post on ls1.com. It is important to get a very accurate measurement of the spring wire diameter though.

;)